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  • Hydrogenation of glucose and fructose into hexitols over heterogeneous catalysts: A review
    J. Taiwan Inst. Chem. E. (IF 3.849) Pub Date : 2018-12-10
    M.J. Ahmed, B.H. Hameed

    Biomass-derived sugars are a promising source of high-value chemicals because of their low cost, availability, and renewability. Catalytic hydrogenation of fructose and glucose into hexitols, including sorbitol and mannitol is of great industrial importance due to hexitols application in the food, medical, chemical, and petroleum industries. For this purpose, heterogeneous catalysts are preferred owing to their high efficiency, easy separation, and reusability. In this review article, the hydrogenation performance of both sugars into hexitols was discussed and analyzed under various reaction conditions. The catalyst stability and hydrogenation kinetics are also reviewed. Moreover, important challenges and promising routes are suggested for the future development of the heterogeneous catalytic hydrogenation of sugars to hexitols.

    更新日期:2018-12-10
  • Dynamic adsorption-desorption of methyl ethyl ketone on MCM-41 and SBA-15 decorated with thermally activated polymers
    J. Ind. Eng. Chem. (IF 4.841) Pub Date : 2018-12-10
    Rafał Janus, Mariusz Wądrzyk, Piotr Natkański, Pegie Cool, Piotr Kuśtrowski

    Three series of mesoporous adsorbents designed for removal of methyl ethyl ketone vapor (MEK) were synthesized: MCM-41 was decorated with various amounts of novolac resin (Nov) and polyacrylonitrile (PAN), while SBA-15 was modified with PAN. The composites were thermally activated towards an enhancement of MEK adsorption capacity and tested in a fixed bed adsorber. Structural features of parent silicas were investigated by XRD, while textural parameters of the composites were studied by nitrogen adsorption. A surface composition was examined by DRIFT and XPS. It was found that decoration of the silica surface with small amounts of PAN improved the monolayer adsorption capacity. The MEK breakthrough curves and desorption profiles were employed for calculation of the monolayer capacity and total pore volume (VtotalMEK). The VtotalMEK for the materials with smaller pores (MCM-41) were comparable to those determined by nitrogen adsorption, whereas respective values for the solids with larger pores (SBA-15) were underestimated. The mechanism of adsorption of MEK onto the adsorbents was elucidated. The MEK molecules were adsorbed solely in the form of keto tautomer. The enhanced MEK adsorption capacity came from the beneficial textural features of the support and the presence of a ladder-type PAN structure containing O-groups.

    更新日期:2018-12-10
  • The Effect of Na Promoter on Fe-Based Catalyst for CO2 Hydrogenation to Alkenes
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-10
    Binglian Liang, Hongmin Duan, Ting Sun, Junguo Ma, Xin Liu, Jinghua Xu, Xiong Su, Yanqiang Huang, Tao Zhang

    ABSTRACT: A series of Fe-based catalysts with accurately controlled amount of Na are synthesized to investigate the relationship between the promoter and the catalytic performance for CO2 hydrogenation to alkenes. With the increasing amount of Na, both CO2 conversion and alkenes selectivity increase at low and moderate amount and then plateau (with the highest to be 36.8% and 64.3%, respectively), while the corresponding methane production decreases to 7.2%. It is found that the addition of Na enhances the adsorption of CO2, facilitates the formation and stability of active species--Fe5C2, and inhibits the secondary hydrogenation of alkenes. All these effects lead to the desirable catalytic performance. Besides, it is observed that the content of Fe5C2 is related to the amount of Na. This study can provide scientific guidance to the design and the synthesis of high-efficiency catalysts for CO2 hydrogenation to high-value chemicals.

    更新日期:2018-12-10
  • Sustainable and affordable composites built using microstructures performing better than nanostructures for arsenic removal
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-10
    Sritama Mukherjee, Avula Anil Kumar, Chennu Sudhakar, Ramesh Kumar, Tripti Ahuja, Biswajit Mondal, Pillalamarri Srikrishnarka, Ligy Philip, Thalappil Pradeep

    Arsenicosis was recognized over 104 years ago. Elevated arsenic (As) concentrations in water is faced by about 200 million people worldwide, and has become one of the biggest challenges in the context of water purification. Providing sustainable and affordable solutions to tackle this menace is a need of the hour. Adsorption on advanced materials is increasingly being recognized as a potential solution. Here, we report various functionalized microcellulose-reinforced 2-line ferrihydrite composites which show outstanding As(III) and As(V) adsorption capacities. Green synthesis of the composite yields granular media with high mechanical strength which show faster adsorption kinetics in a wide pH range, irrespective of the presence of other interfering ions in water. The composites and their interaction with As(III) and As(V) were studied by XRD, HRTEM, SEM, XPS, Raman, TG and IR spectroscopy. Performance of the media in the form of cartridge reaffirms its utility for point-of-use water purification. We show that cellulose microstructures are more efficient than corresponding nanostructures for the purpose of arsenic remediation. We have also performed an evaluation of several sustainability metrics to understand the “greenness” of the composite and its manufacturing process.

    更新日期:2018-12-10
  • Understanding the role of water flow and the porous transport layer on the performance of Proton Exchange Membrane Water Electrolyzers
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-10
    Julio Cesar Garcia Navarro, Mathias Schulze, K. Andreas Friedrich

    In this article, we have brought a different perspective to the topic of mass transport losses in a Proton Exchange Membrane (PEM) water electrolyzer, particularly to the role of water flow and on the dominant mass transport mechanism in the Porous Transport Layer (PTL). We conducted permeation experiments on a sintered Ti PTL, where we measured the pressure loss of gas that flows through its pores; furthermore, we presented a model based on the van Genuchten-Mualem capillary pressure and the Carman-Kozeny gas permeability, and we report an increase in the pressure loss with respect to the water flow, which we reported as an increase in the apparent tortuosity of the pores in the PTL. From this we conclude that the water flow exerts a shear stress on the gas flowing through the PTL, proportional to its kinetic energy, and that the gas permeation is the dominant transport mechanism within a PTL, in contrast to a one- or two-phase flow, which is more energy demanding. Finally, we propose that further work be carried out, in particular by comparing these results to in-situ measurements on an operating PEM electrolyzer.

    更新日期:2018-12-10
  • Highly Unsaturated Microcrystalline Cellulose and its Crosslinked Soybean Oil-based Thermoset Composites
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-10
    Tingting Chen, Wendi Liu

    Microcrystalline cellulose (MCC) was highly decorated with unsaturation functionality through esterification with methacrylic anhydride (MAA) with the assistance of ultrasonic treatment. The degree of unsaturation on the MCC surface was tailored by adjusting the mass ratio of MAA to MCC during the modification process. The unsaturated-MCC was characterized by FTIR, XRD, XPS, NMR, and contact angle measurements. The degrees of substitution and unsaturation of the unsaturated-MCC were quantitatively determined by NMR and XPS analyses to reveal the grafting efficiency of MAA on MCC surface. The unsaturated-MCC was further used as a reactive reinforcing agent for crosslinking with acrylated epoxidized soybean oil (AESO) to manufacture fully biobased MCC/AESO composites. The crosslinking mechanism between the unsaturated-MCC and AESO was discussed through the curing kinetic behavior of the MCC/AESO systems based on Kissinger’s theory. The unsaturation functionalization of MCC resulted in significantly improved flexural strength and modulus, water resistance, storage modulus, glass transition temperature, thermal stability, and interfacial adhesion of the resulting unsaturated-MCC/AESO composites.

    更新日期:2018-12-10
  • Examining the Implications of Wax-Based Additives on the Sustainability of Construction Practices: Multiscale Characterization of Wax-Doped Aged Asphalt Binder
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-09
    Alireza Samieadel, Bjarke Høgsaa, Elham H. Fini

    Paraffin wax is a component of many additives and rejuvenators commonly used in the asphalt industry to promote sustainability by facilitating recycling and/or reducing mixing and compaction temperatures during pavement construction. However, the effect of wax-based additives on asphalt molecules and consequently on asphalt binder’s performance characteristics has not been thoroughly understood. This paper uses a combination of a computational approach and an experimental approach to study the properties of aged asphalt binder specimens in the presence of paraffin wax. Differential scanning calorimetry showed that the introduction of paraffin wax to aged asphalt significantly reduces the glass transition temperature of the aged asphalt, with 10% wax-doped aged asphalt having a glass transition temperature 9 degrees lower than the control asphalt. The above observations can be attributed to a plausible role of straight alkane chains of wax in disturbing the clusters of asphaltenes and increasing asphaltene mobility. The increase in asphaltene mobility is also reflected in the rheology of wax-doped aged asphalt; its percent recovery in the presence of 10% wax is reduced by 50% compared to the control. The results of molecular dynamics simulations revealed how paraffin wax molecules change the aggregation pattern of aged asphalt binder, as evidenced by the reduced formation of nanoaggregates in oxidized asphaltene in the presence of wax molecules. The reduced formation of nanoaggregates is described as a three-step mechanism: the attraction of wax molecules to nanoaggregates of oxidized asphaltene; the penetration of wax molecules to self-assembled asphaltene stacks; and disturbances in the formation of parallel oxidized asphaltene stacks. The results show the average aggregation number is reduced after adding paraffin wax molecules to an equilibrated system of oxidized asphaltene molecules. Furthermore, the radial distribution function confirms that after the addition of paraffin wax molecules, the formation of parallel stacks of oxidized asphaltene is less likely. Thermogravimetric analysis shows that the addition of wax to aged asphalt binder increases the onset temperature of degradation; an increase of 25 degrees is recorded when the wax dosage increases from 1% to 10%. The overall thermal stability of asphalt binder is reduced, as evidenced by lower residual mass in samples with higher wax content. In addition, the difference in critical cracking temperatures (determined based on the stiffness and the stress relaxation capability of the asphalt binder) increases as the wax content increases. This in turn indicates that the cracking properties of wax-doped binder are controlled mainly by the stiffness rather than by the stress relaxation capability; the control of cracking properties by stiffness could be attributed to the formation of lamellar structure in wax-doped aged asphalt binder, causing a significant increase in stiffness. A molecular-level understanding of wax-asphaltene interaction helps explain how the performance of aged asphalt binder is affected by wax-based additives commonly added to asphalt binder to promote sustainability by facilitating the recycling of aged asphalt and/or reducing the mixing and compaction temperatures.

    更新日期:2018-12-10
  • Using partial nitrification and anammox to remove nitrogen from low-strength wastewater by co-immobilizing biofilm inside a moving bed bioreactor
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-09
    Rong Chen, Yasuyuki Takemura, Yuan Liu, Jiayuan Ji, Satoshi Sakuma, Kengo Kubota, Haiyuan Ma, Yu-You Li

    The stable operation of partial nitrification and anammox (PNA) process is a challenge in nitrogen removal from extremely low-strength ammonia wastewater like sewage mainstream. A moving bed reactor with functional carriers (30% filling rate) was developed to treat a synthetic influent with 50 mg/L ammonia. The long-term operation results showed nitrogen removal efficiencies of 71.7±9.1% have been stably obtained under a relatively short hydraulic retention time (HRT) of 2h. Microbial analysis revealed anammox bacteria and ammonium oxidizing bacteria (AOB) with 29.7% and 6.32% abundance were the two most dominant bacteria in the reactor. Carriers largely retained slow-growing anammox bacteria in their hollow space and established a sandwich-like biofilm structure of co-immobilization of anammox bacteria and AOB. The anammox activity was much higher in carrier biofilms than in suspended flocs while for the AOB activity, the situation was reversed. Correspondingly, a fluorescent in situ hybridization analysis illustrated the active cell fractions of anammox bacteria and AOB in carrier biofilms were 63.7% and 4.8%, and 2.7% and 61.4% in suspended flocs. Biofilm formation and dissolved oxygen control were deemed to be the two key factors affecting the optimal co-immobilization of anammox bacteria and AOB, which guaranteed the efficient PNA.

    更新日期:2018-12-10
  • Conceptual design and analysis of a novel CO2 hydrate-based refrigeration system with cold energy storage
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-09
    Nan Xie, Chenghua Tan, Sheng Yang, Zhiqiang Liu

    CO2 hydrate can be used as an alternate cooling substance in the air-conditioning system, to minimize the use of traditional refrigerants such as HFCs and HCFCs. A novel CO2 hydrate-based refrigeration system with a function of cold energy storage was designed and investigated, using tetrahydrofuran (THF) as the thermodynamic promoter. Coefficient of performance (COP) of this system was calculated based on the simulation results. Effects of various operation parameters were also studied closely. The cold storage operation was then designed to investigate the energy storage ability of the current system. Results show that the system COP is 6.8, which is the major strength of this novel system. Due to the energy intensive process of CO2 compression, the work imposed on elevating the gas pressure was considerable. Searching for more appropriate additives or alternate guest substances should be further conducted. Besides, compressor efficiency and pump efficiency are both critical for improving the energy efficiency. Enhanced refrigeration performance can also be realized at higher hydrate mass fraction. In addition, two different cold energy storage operation strategies were obtained. This research is of great significance to the in-depth development of hydrate-based refrigeration and cold energy storage system. The proposed system might contribute to minimizing the use of conventional coolants and realizing peak load shifting in the near future.

    更新日期:2018-12-10
  • Efficient ketose production by hydroxyapatite catalyst in a continuous flow module
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-09
    Kaho Usami, Kejing Xiao, Akimitsu Okamoto

    Ketose is a valuable industrial ingredient, but there is no effective synthetic method for ketoses. A hydroxyapatite (HAp)-loaded flow system was developed for atom-economical ketose preparation. This continuous flow system enables the efficient transformation from aldoses to valuable ketoses. Especially, ketotriose dihydroxyacetone was obtained quantitatively from glyceraldehyde in water through a HAp-packed column reactor without any decrease in yield during long-term operation.

    更新日期:2018-12-10
  • Modelling bubble induced turbulence for gas-liquid bubbly flow in a vertical pipe
    Chem. Eng. Sci. (IF 3.306) Pub Date : 2018-12-07
    A.S.M. Atiqul Islam, D.J. Bergstrom

    A two-fluid model in the Eulerian-Eulerian framework has been implemented for the turbulent gas-liquid bubbly upward flow in a vertical pipe. The transport equations, i.e. Reynolds-Averaged Navier-Stokes equations for the two-fluid model, are discretized using the finite volume method. The effect of the disperse gas phase on the liquid phase turbulence, referred to as turbulence modulation, was accounted for through source terms in the transport equations for a low Reynolds number k-ε turbulence closure. The model was used to predict the turbulence kinetic energy and its dissipation rate, mean phasic velocities and volume fraction distribution for a set of test cases selected from the available literature. The focus of the present study was on assessing the model predictions using measurements of the turbulence kinetic energy of the liquid phase. A relatively novel aspect of the present analysis is the use of the budgets of the transport equations for the turbulence kinetic energy and dissipation rate to assess the effect of the turbulence modulation on the liquid turbulence field. Although the present model formulation is shown to adequately predict the effect of bubbles in some flows and perform better than some of the other model formulations, the overall conclusion is that the present approaches for incorporating turbulence modulation are at best partially successful and still need further development.

    更新日期:2018-12-09
  • Liquid-liquid extraction in laminar two-phase stratified flows in capillary microchannels
    Chem. Eng. Sci. (IF 3.306) Pub Date : 2018-12-07
    Sundari Ramji, S. Pushpavanam

    In this work, we study the mass transfer of a solute in laminar, two-phase, stratified flow in a circular microchannel. The model developed in our earlier work (Picardo et al., 2015) has been used. We adopt a semi-analytical approach to model liquid-liquid extraction in the circular channel with stratified flow. A bipolar cylindrical coordinate system is employed for an elegant description of the boundaries in the form of iso-coordinate surfaces.The model developed for the circular channel is computationally intensive. We present a methodology to estimate the mass transfer predictions for the 2D circular channel from a 2D channel of rectangular cross-section and a 1D channel i.e. flow between infinite parallel plates. This is analyzed for different carrier phase holdups and fluid properties. It is found that the 1D model can accurately predict the performance of the capillary. Further, we conclude that a more viscous carrier phase results in enhanced mass transfer.

    更新日期:2018-12-09
  • Extracellular redox potential regulation improves yeast tolerance to furfural
    Chem. Eng. Sci. (IF 3.306) Pub Date : 2018-12-07
    Kai Li, Juan Xia, Muhammad Aamer Mehmood, Xin-Qing Zhao, Chen-Guang Liu, Feng-Wu Bai

    Furfural is a major toxic byproduct present in the hydrolysate of lignocellulosic biomass, which inhibits the growth and ethanol fermentation of Saccharomyces cerevisiae. To enhance yeast tolerance to furfural, extracellular redox potential (ORP) regulation was employed for the fermentation system through controlling ORP at -150 mV, -100 mV and -50 mV, respectively, by adjusting its aeration. When ORP was controlled at -100 mV, yeast cells exhibited improved growth, furfural degradation and ethanol production. Analysis of intracellular redox pairs such as NADH/NAD+ and GSH/GSSG indicated a correlation between extracellular ORP and intracellular redox homeostasis. Moreover, intracellular reactive oxygen species (ROS) caused by furfural stress decreased under the redox control condition, which consequently conferred yeast cells tolerance to furfural. Comparative transcriptome analysis for yeast cells sampling under the ORP control at -100 mV further revealed that the expression of genes for proliferation was up-regulated to degrade furfural more efficiently. These results demonstrated that extracellular ORP regulation would be a strategy for enhancing yeast tolerance to furfural stress during cellulosic ethanol fermentation.

    更新日期:2018-12-09
  • An evaluation of in-silico methods for predicting solute partition in multiphase complex fluids – a case study of octanol/water partition coefficient
    Chem. Eng. Sci. (IF 3.306) Pub Date : 2018-12-08
    Mattia Turchi, Qiong Cai, Guoping Lian

    Solute partition in multiphase fluids is an important thermodynamic phenomenon and performance attribute for a wide range of product formulations of foods, pharmaceuticals and cosmetics. Experimental evaluation of partition coefficients in complex product formulations is empirical, difficult and time consuming. In-silico methods such as fragment constant method and group contribution method require parameter fitting to the experimental data and are limited to relatively simple fluids. Recently, a method combining molecular dynamics (MD) and quantum chemical (QC) calculation of screening charge density function has been reported. The method does not only use fundamental properties of intermolecular force and charge density function, which does not require parameter fitting to the experimental data, but also applies to complex fluid structures such as micelles. In this work, the predictive accuracy of the combined method of MD and QC is evaluated. Using widely available octanol-water partition coefficients as a case study, the performance of the combined MD and COSMOmic for predicting octanol/water partition coefficients has been compared with those of the EPI Suite TM fragment constant method, UNIFAC group contribution method and COSMOtherm. The prediction of the combined MD/COSMOmic method is the closest to the best performing fragment constant method which was specifically designed for the octanol-water system. The combined MD/QC method proves to be the most promising and robust method applicable to a wide range of complex structures of multiphase fluid systems.

    更新日期:2018-12-09
  • Supported Mn catalysts and the role of different supports in the catalytic oxidation of carbon monoxide
    Chem. Eng. Sci. (IF 3.306) Pub Date : 2018-12-08
    Sajad Mobini, Fereshteh Meshkani, Mehran Rezaei

    The effects of the carrier and the content of the active species were studied in the carbon monoxide oxidation process. MnOx catalysts supported on ZrO2, CeO2, MgO, SiO2, and Al2O3 were prepared and characterized by XRD, BET-BJH, FE-SEM, EDX, TPR, and CO2-TPD analyses. The relation between the textural properties of the catalysts and the catalytic performance was investigated. The results showed that Mn/CeO2 catalyst despite of its lowest surface area (55.5 m2/g) possessed the highest activity among other catalysts. High ability to supply oxygen through the support during the reaction is the most important reason for the proper performance of this catalyst. The investigation of the Mn content indicated that the 20 wt.% Mn/CeO2 showed high dispersion, appropriate reducibility and the highest concentration of active sites compared to other catalysts with various Mn contents. The temperature corresponding to 50% of the CO conversion (T50) was about 142 °C , which was 20 °C lower than the other samples. In addition, the influence of different parameters including pretreatment condition, feed ratio, and GHSV was examined on the catalytic performance. The results showed that the catalytic stability declined with the incorporation of water vapor and CO2 in the feed mixture.

    更新日期:2018-12-09
  • Three-dimensional numerical simulation of gas-liquid interfacial mass transfer with Rayleigh convection using hybrid LBM-FDM and its mass transfer coefficient model
    Chem. Eng. Sci. (IF 3.306) Pub Date : 2018-12-08
    Xiaolong Ge, Botong Liu, Botan Liu, Hongxing Wang, Xigang Yuan

    Rayleigh convection has a significant effect on gas-liquid interfacial mass transfer. However, its intensified mechanism has not been clarified so far. In the present work, three-dimensional hybrid Lattice Boltzmann Method-Finite Difference Method (LBM-FDM) was employed to simulate the Rayleigh convection emerging in the CO2-ethanol absorption process. A gas phase random disturbance model was applied to represent the disturbances on the gas-liquid interface which effectively induces Rayleigh convection. Then the front view images obtained by three-dimensional simulation were compared to the Schlieren observations for validation. Finally, a theoretical mass transfer coefficient model based on dissipation rate of concentration variance was proposed, by analyzing the overhead view of concentration contour and dissipation rate of concentration variance contour. Compared to the small eddy model and surface divergence model, the proposed model shows its strength in determining molecular diffusion stage and convective mass transfer stage of Rayleigh convection process, as well as eliminating the phase difference in model prediction.

    更新日期:2018-12-09
  • Adsorption and Structure of Benzene, Toluene, and p-Xylene in Carbon Slit Pores: A Monte Carlo Simulation Study
    Chem. Eng. Sci. (IF 3.306) Pub Date : 2018-12-08
    Rui Diao, Hongyang Zhang, Dongfeng Zhao, Shi Li

    The adsorption of benzene (B), toluene (T), and p-xylene (X) at ambient temperature in carbon slit pores was studied using the grand canonical Monte Carlo simulation. We focused on how the structure of the adsorbed B, T, and X molecules is influenced by pore size, in particular the effects of the methyl groups in the cases of toluene and p-xylene. The packing density of the compounds in the pores was found to follow the order B < T < X at low loadings but X < T < B at high loadings. Furthermore, various molecular orientations were observed in the different pore sizes, including parallel, perpendicular, and parallel combined with perpendicular, and the nearest neighboring molecules assumed to undergo an edge-wise or T-shaped interaction. For parallel molecules, two adjacent molecules were aligned in an edge-wise interaction, which is the most favorable for solid–fluid interactions. However, for perpendicular molecules, two adjacent molecules were arranged in a T-shape, which is more favorable for fluid-fluid interactions. For the perpendicular toluene and p-xylene molecules, the angle between the methyl group and the pore walls was found to be 30°. In the smallest pore studied, the benzene molecules were found to adopt a 2D hexagonally packed solid-like state, whereas the toluene and p-xylene molecules were in a liquid-like state. Consequently, the microscopic structures of B, T, X in various sized pores were investigated. The molecular models showed that the fluid-fluid interactions were significant for B, T, X adsorption, except for the cases of toluene and p-xylene in pores that can accommodate more than one molecular layer, where the solid–fluid interactions play a more dominant role because of the enhanced solid–fluid interactions of the toluene and p-xylene molecules oriented in parallel to each other. In addition, we have compared the results of our simulation with experimental data from previous research. The simulated isotherm agrees reasonably well with the experimentally obtained isotherm, and the simulated nearest-neighbor distance between the adsorbed molecules is almost the same as the experimental value.

    更新日期:2018-12-09
  • Fractal continuum model for the adsorption-diffusion process
    Chem. Eng. Sci. (IF 3.306) Pub Date : 2018-12-08
    E.C. Herrera-Hernández, C.G. Aguilar-Madera, R. Ocampo-Perez, G. Espinosa-Paredes, M. Núñez-López

    In this work, we present a mathematical model to describe the adsorption-diffusion process on fractal porous materials. This model is based on the fractal continuum approach and considers the scale-invariant properties of the surface and volume of adsorbent particles, which are well-represented by their fractal dimensions. The method of lines was used to solve the nonlinear fractal model, and the numerical predictions were compared with experimental data to determine the fractal dimensions through an optimization algorithm. The intraparticle mass flux and the mean square displacement dynamics as a function of fractal dimensions were analyzed. The results suggest that they can be potentially used to characterize the intraparticle mass transport processes. The fractal model demonstrated to be able to predict adsorption-diffusion experiments and jointly can be used to estimate fractal parameters of porous adsorbents.

    更新日期:2018-12-09
  • Effect of the Laser Power on the Mechanical Performance of the Laser Spot Welds in Dual Phase Steels
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-12-07
    Jaydeb Kundu, Trishita Ray, Amrita Kundu, Mahadev Shome

    Fibre laser spot (circular) welds (LSW) in dual phase DP 780 steel grade were produced with fusion areas equivalent to conventional resistance spot welds (RSW) using different fibre laser parameters. Shear tensile properties show significantly higher loads in fibre laser spot welds primarily because of the combined strength of spot size, and hard microstructures in the fusion zone and heat-affected zone (HAZ). Greater HAZ softening is observed at high heat inputs. The transition of failure mode from interfacial to pull-out and the corresponding strength value is primarily controlled by the weld size. The crack initiation site and propagation mechanism were observed to be different for interfacial and pull-out failure. The increased HAZ softening with increase heat input was quantified with nano-indentation hardness measurement technique.

    更新日期:2018-12-08
  • Direct Coupling of Continuum and Kinetic Monte Carlo Models for Multiscale Simulation of Electrochemical Systems
    Comput. Chem. Eng. (IF 3.113) Pub Date : 2018-12-07
    Fridolin Röder, Richard D. Braatz, Ulrike Krewer

    Electrochemical systems include atomistic processes at electrochemical interfaces and macroscopic transport processes, which can be modeled using kinetic Monte Carlo (kMC) simulation and continuum equations, respectively. Multiparadigm algorithms are applied to directly couple such models to study multiscale interactions. This article compares different algorithms for an example problem. Results quantify the effect of computational cost and numerical accuracy by the choice of algorithm and its configuration. The stochastic fluctuations of kMC simulations as well as sequential data exchange between the models generate errors in coupled simulations. Measures to reduce stochastic fluctuations or revise exchanged data can be either highly successful or futile, depending on the dominant cause of the error. Hence, we strongly advise to identify the different causes of errors and their mechanics when selecting a coupling algorithm or optimizing its configuration. This article provides various algorithms and suggestions for their configuration to enable efficient and robust multiscale simulations.

    更新日期:2018-12-08
  • A Novel Cost-effective Silica Membrane-based Process for Helium Extraction from Natural Gas
    Comput. Chem. Eng. (IF 3.113) Pub Date : 2018-12-08
    Homa Hamedi, Iftekhar A. Karimi, Truls Gundersen

    Natural gas reserves with 0.3-2 mol% helium are considered as the only viable source for this noble gas. Currently, cryogenic separation is used to extract helium, but it is energy-intensive. While membrane-based separation is a promising alternative, it is still not considered economical. Even for an inorganic/silica membrane with relatively high selectivity and permeance, a multi-stage membrane system with inter-stage compression is required, which necessitates high CAPEX and OPEX. This study proposes a novel process to enhance the selectivity and permeance of an inorganic/silica membrane system to eliminate the costly inter-stage compression. A 16-24% reduction in the CAPEX and 23-57% in the OPEX are achievable for a natural gas feed with 3-5 mol% helium. In contrast, for a 2 mol% helium feed, the OPEX increases by 34%. However, a 30% decrease in the capital cost outweighs the OPEX increase to make the new process more profitable.

    更新日期:2018-12-08
  • Well Control Optimization using Derivative-Free Algorithms and a Multiscale Approach
    Comput. Chem. Eng. (IF 3.113) Pub Date : 2018-12-08
    Xiang Wang, Ronald D. Haynes, Yanfeng He, Qihong Feng

    Smart well technologies, which allow remote control of well and production processes, make the problem of determining optimal control strategies a timely and valuable pursuit. The large number of well rates for each control step make the optimization problem difficult and present a high risk of achieving a suboptimal solution. Moreover, the optimal number of adjustments is not known a priori. Adjusting well controls too frequently will increase unnecessary well management and operation cost, and an excessively low number of control adjustments may not be enough to obtain a good yield. In this paper, we explore the capability of three derivative-free algorithms and a multiscale regularization framework for well control optimization over the life of an oil reservoir. The derivative-free algorithms chosen include generalized pattern search (GPS), particle swarm optimization (PSO) and covariance matrix adaptation evolution strategy (CMA-ES). These algorithms, which cover a variety of search strategies (global/local search, stochastic/deterministic search), are chosen due to their robustness and easy parallelization. Although these algorithms have been used extensively in the reservoir development optimization literature, for the first time we thoroughly explore how these algorithms perform when hybridized within a multiscale regularization framework. Starting with a reasonably small number of control steps, the control intervals are subsequently refined during the optimization. Results for the experiments studied indicate that CMA-ES performs best among the three algorithms in solving both small and large scale problems. When hybridized with a multiscale regularization approach, the ability to find the optimal solution is further enhanced, with the performance of GPS improving the most. Topics affecting the performance of the multiscale approach are discussed in this paper, including the effect of control frequency on the well control problem. The parameter settings for GPS, PSO, and CMA-ES, within the multiscale approach are considered.

    更新日期:2018-12-08
  • Control of Complex Sociotechnical Systems: Importance of Causal Models and Game Theory
    Comput. Chem. Eng. (IF 3.113) Pub Date : 2018-12-08
    Venkat Venkatasubramanian, Yu Luo, Zhizun Zhang

    Recent systemic failures in different domains have reminded us, once again, of the fragility of complex sociotechnical systems. Although the failures occurred in very different domains, there are, however, certain common underlying mechanisms driving these disasters. Understanding these mechanisms is essential to avoid such disasters in the future. To understand them, one needs to go beyond analyzing them as independent one-off accidents, and examine them in the broader perspective of the potential fragility of sociotechnical systems. It is their scale, nonlinearities, inter-connectedness, and interactions with humans and the environment that can make these systems fragile. Here we present an overview of the challenges and opportunities in the modeling and analysis of sociotechnical systems. We highlight a control-theoretic modeling framework that unifies the social and the technical components. We discuss how certain problems can be addressed by using concepts and techniques from causal modeling, game theory, and behavioral economics.

    更新日期:2018-12-08
  • Intensification of large-scale cell culture processes
    Curr. Opin. Chem. Eng. (IF 4.033) Pub Date : 2018-12-07
    Martin Jordan, Nicola Mac Kinnon, Vincent Monchois, Matthieu Stettler

    Manufacturers of recombinant proteins frequently face the challenge to satisfy the market needs with existing large scale production capacity. For fed-batch processes, the maximal capacity is given in yield per batch multiplied by the number of runs that can be done per year, thus strongly depending on the duration of the fed-batch run. This short review is focused on starting the fed-batch at high seeding densities, reducing the duration of the fed-batch as an efficient strategy to increase the manufacturing capacity without modifying the production bioreactor. This strategy makes fed-batch processes highly productive from the first day on.

    更新日期:2018-12-08
  • Advancing manufacture of human mesenchymal stem cells therapies: technological challenges in cell bioprocessing and characterization
    Curr. Opin. Chem. Eng. (IF 4.033) Pub Date : 2018-12-06
    Margarida Serra, Bárbara Cunha, Cristina Peixoto, Patrícia Gomes-Alves, Paula M Alves

    The use of human mesenchymal stem/stromal cells (hMSC) in clinical trials has been exponentially increasing over the last decade. To meet the high-growth demand for high quality hMSC products, much research and many reports have been published on bioprocess development for hMSC production in bioreactors, their downstream processing and on the development of analytical tools for standardization and harmonization of functional assays to assess hMSC potency. Here we discuss the last advances in hMSC manufacturing that have been designed through a better understanding of the attributes critical for assuring product quality, safety and therapeutic efficacy.

    更新日期:2018-12-08
  • Liquid CO2 Behaviour during Water Displacement in a Sandstone Core Sample
    J. Nat. Gas Sci. Eng. (IF 2.803) Pub Date : 2018-12-07
    Ebraheam Al-Zaidi, Xianfeng Fan

    CO2 sequestration in saline aquifers and hydrocarbon reservoirs is a potential strategy to reduce CO2 concentration in the atmosphere, enhance hydrocarbon production, or extract geothermal heat. CO2 injection is considerably influenced by the interfacial interactions, capillary forces and viscous forces. Any change in the subsurface conditions of pressure, temperature, and salinity is likely to have an impact on the interfacial interactions, capillary forces and viscous forces, which, in turn, will have an influence on the injection, migration, displacement, and CO2 storage capacity. In this study, unsteady-state immiscible experimental investigations have been performed to explore the impact of fluid pressure, temperature, salinity (brine concentration and valency) and injection rate on the dynamic pressure evolution and displacement efficiency when CO2 as a liquid phase is injected into a water-saturated sandstone core sample. This study also highlights the impact of capillary forces and viscous forces on the two-phase flow properties and shows when capillary forces or viscous forces are dominant. The results reveal a moderate to considerable impact for the fluid pressure, temperature, injection rate, and salinity on the differential pressure profile, water recovery (WR), endpoint CO2 relative permeability (KrCO2), and cumulative produced volumes. Overall, increasing fluid pressure, CO2 injection rate and salinity (brine concentration and valency) cause an increase in the differential pressure profile; the highest increase occurred with the injection rate. In general, increasing temperature caused a reduction in the differential pressure profile. The WR is in range of around 61.6-69.3% while the KrCO2 is in range of 0.112-0.203, depending on the investigated parameters. Increasing fluid pressure and injection rate caused an increase in the WR; the highest increase occurred with the injection rate. On the other hand, increasing temperature and salinity caused a decrease in the WR; the highest reduction occurred with salinity. Nevertheless, the increase in fluid pressure, temperature, injection rate and salinity led to a reduction in the endpoint CO2 relative permeability; the highest reduction occurred with increasing temperature whilst the lowest occurred with increasing fluid pressure. The cumulative injected volumes decreased with fluid pressure and salinity but showed no noticeable change with temperature and injection rate. The capillary forces have less impact on the differential pressure profiles than viscous forces when fluid pressure, temperature and injection rate increase but the capillary forces have more impact when salinity increase.

    更新日期:2018-12-08
  • Using rate based simulation, sensitivity analysis and response surface methodology for optimization of an industrial CO2 capture plant
    J. Nat. Gas Sci. Eng. (IF 2.803) Pub Date : 2018-12-07
    Abbas Hemmati, Hamed Rashidi, Abdollsaleh Hemmati, Abolghasem Kazemi

    Using optimum conditions in CO2 capture processes to maximize CO2 capture capacity and rich amine temperature leads to saving energy and reducing costs. In the present article, an industrial CO2 capture process with aqueous MEA was studied using the sensitivity analysis and an optimization method. The process was simulated using a rate-based model. The results were validated against four different industrial operational data. In the four different industrial situations, the average relative error was 1.38 % to 3.85 %. The liquid temperature profiles and CO2 absorption (%), calculated by the model agree with the real operational data. In the second part of the work, a sensitivity analysis of the absorption column’s important variables was carried out to determine sensitive parameters for CO2 absorption capacity and rich MEA temperature. The variables are gas flow rate, solvent flow rate, flue gas temperature, inlet solvent temperature, CO2 concentration in the flue gas, loading of inlet solvent, and MEA concentration. Based on the results, all of the operational parameters except the inlet solvent and the inlet liquid temperature are considered influential. In the third and final part of the article, the operational conditions are optimized to maximize CO2 absorption (%) and rich solvent temperature. Response surface methodology (RSM) is used as a statistical optimization tool. The experimental design data were analyzed by analysis of variance (ANOVA) and fitted to the second-order polynomial equation using multiple regression analysis. By applying the optimum operational conditions in the model, CO2 absorption (%) and rich solvent temperature of 95.63 % and 56.15 °C can be obtained, which indicate 13 % and 17 % increase, respectively compared to the base case. The results showed that the absorber’s energy consumption is decreased by 16 %, when applying optimum operational conditions. In contrary to previous studies, it is found that rich solution temperature is not a function of lean solution temperature. According to the results, the inlet gas flow rate is the most influential parameter in CO2 absorption and rich solution temperature.

    更新日期:2018-12-08
  • Effects of water invasion law on gas wells in high temperature and high pressure gas reservoir with a large accumulation of water-soluble gas
    J. Nat. Gas Sci. Eng. (IF 2.803) Pub Date : 2018-12-07
    Xiaoliang Huang, Xiao Guo, Xiang Zhou, Chen Shen, Xinqian Lu, Zhilin Qi, Qianhua Xiao, WendeYan

    A high temperature and high pressure (HTHP) gas reservoir with a large accumulation of water-soluble gas contains a large amount of dissolved gas in formation water. The dissolved gas in the formation water will be released due to formation pressure depletion in the production process. At present, few researches have been done on water invasion law of gas wells regarding the released dissolved gas, especially when the change rule of water and gas is not clear in porous media after the release of water-soluble gas, which leads to the unclear water invasion law and the gas reservoirs cannot be developed efficiently. In this paper, a visualization sand filling tube is used to conduct experiments to study the effects of the dissolved gas on the law of the gas-water contact (GWC) changes in the water-soluble gas release process. The experimental results show that the release of dissolved gas leads to a GWC rise at the beginning of the depressurization process. After the pressure drops to a lower level, the GWC will decline due to a large amount of dissolved gas being released from formation water. Subsequently, numerical simulations are performed to study the effects of different solubilities of natural gas, the gas production rate, the aquifer size, and stress sensitivity on the water invasion law of the gas well. The simulation results show that a greater solubility of natural gas, a higher gas production rate, a larger aquifer size, and the existence of stress sensitivity all lead to stronger bottom water coning and an early water break-through. For the non-coning region, a greater solubility of natural gas will lead to a slower rise in the GWC. The simulation results show that the water invasion velocity with water-soluble gas is faster than the velocity without water-soluble gas.

    更新日期:2018-12-08
  • Condensate Blockage Alleviation around Gas-Condensate Wells using Wettability Alteration
    J. Nat. Gas Sci. Eng. (IF 2.803) Pub Date : 2018-12-07
    Seyed-Ahmad Hoseinpour, Mehdi Madhi, Hamidreza Norouzi, Bahram Soltani Soulgani, Amir H. Mohammadi

    In the current survey, a novel fluorocarbon-based wettability modifier chemical is proposed to alter the wettability of sandstone rock surface from liquid wetting to preferentially gas wetting condition. Several experimental tests describing wettability condition of the rock surface including static contact angle measurements, spontaneous imbibition and dynamic core flooding using water and n-decane fluids were conducted on untreated and treated sandstone rock to investigate the effect of the proposed chemical on surface wetting behavior. Adsorption of fluorinated chemical on sandstone surfaces was characterized using FTIR and SEM. Elemental analysis of rock surface after treatment was determined by EDX analysis and EDX map. After chemical treatment of sandstone thin section, contact angles of water and n-decane in air-liquid-rock system were altered from 0° and 0° to 151° and 101°, respectively. Spontaneous imbibition of water and n-decane as imbibing liquid fluids into the core sample saturated with dry air at room temperature on untreated and treated core showed that the ultimate amount of liquid imbibition was decreased to a factor of 0.03% and 0.16%, demonstrating wettability alteration from strongly condensate-and water-wet to preferentially gas-wet condition, respectively. Also, the results of core flooding experiments demonstrated the improvement of liquid phase mobility as a result of treatment with proposed chemical fluid by factors of 3.85 and 3.5 for water and n-decane, respectively. The outcome of this integrated study proposes that fluorochemical agents can be considered as a promising candidate for possible field applications to alleviate both condensate and water blockage in gas condensate reservoirs by wettability alteration technique.

    更新日期:2018-12-08
  • A comparative study of different mass transfer and liquid hold-up correlations in modeling CO2 absorption with MEA
    J. Nat. Gas Sci. Eng. (IF 2.803) Pub Date : 2018-12-08
    Abbas Hemmati, Hamed Rashidi, Kourosh Behradfar, Abolghasem Kazemi

    Although CO2 absorption processes have been widely studied in both laboratory and industrial scales, the viability of different relations for the estimation of mass transfer coefficients has not been studied for industrial units. In this paper, the accuracy of different various equations for the estimation of mass transfer coefficients were are evaluated and compared, on the basis of according to the results of an industrial CO2 absorption unit. Therefore, the relations proposed by Onda, Bravo and Billet-Schules were are selected. Also, in some parts of the column pall ring packing was is used. in these parts the Hanley mass transfer coefficients were also used. In addition, Hanley mass transfer coefficients are used for those parts of the column in which pall ring packing is used. Based on the results of rate-based modeling of the column, obtained results show that the Onda equations show have higher accuracy compared to the other mass transfer equations. The comparison was is carried out based on CO2 absorption capacity, temperature profile and rich solvent concentration. The average errors of Onda’s mass transfer correlations and Billet & Schultes’s liquid holdup correlations in estimating CO2 absorption (%), temperature of rich solvent’s temperature, temperature of outlet water’s temperature and loading of rich solvent’s loading were are 1.153, 2.923, 6.99 and 1.163 % respectively. Onda and Billet & Schultes correlations exhibited the most accurate results. Also additionally, liquid film discretization shows indicates that the reaction occurs almost rather instantaneously at liquid-vapor interface and diffusion is the controlling step in the absorption process.

    更新日期:2018-12-08
  • Thermal stability and corrosion of tertiary amines in aqueous amine and amine-glycol-water solutions for combined acid gas and water removal
    J. Nat. Gas Sci. Eng. (IF 2.803) Pub Date : 2018-12-08
    Usman Shoukat, Eva Baumeister, Diego D.D. Pinto, Hanna K. Knuutila

    Thermal stability and corrosion of seven tertiary amines (20 wt.%) solutions in water and water-glycol [ethylene glycol (MEG)/tri-ethylene glycol (TEG)] loaded with CO2 in stainless steel reactors has been studied for combined acid gas removal along with hydrate control. The pKa of the tested amines varied from 7.85 to 9.75. Titration and inductivity coupled plasma mass spectrometry (ICP-MS) are used to quantify the remaining alkalinity and metal concentrations in amine solutions respectively. The presence of MEG and TEG profoundly influenced the amine stability. Triethanolamine had the highest thermal stability. Furthermore, the results also show that an increase in pKa generally decreases corrosion. 3-(Diethylamino)-1,2-propanediol (DEA-1,2-PD) has the lowest corrosion in water and water-TEG solutions while 2-(Diethylamino)ethanol (DEEA) has the least corrosion in water-MEG solutions.

    更新日期:2018-12-08
  • Flexible, Durable and Thermal Conducting Thiol-modified rGO-WPU/Cotton Fabric for Robust Electromagnetic Interference Shielding
    Chem. Eng. J. (IF 6.735) Pub Date : 2018-12-07
    Yu Wang, Wei Wang, Rui Xu, Meifang Zhu, Dan Yu

    In this paper, we proposed a novel method to fabricate thiol-modified reduced graphene oxide-waterborne polyurethane/cotton (M-rGO-WPU/cotton) fabric that provided a robust electromagnetic interference (EMI) shielding performance and excellent thermal conductivity. The WPU molecules with ene groups at the both ends were synthesized and acted as a polymer matrix to connect the rGO and cotton substrate with the thiols via the synchronous thiol-ene click reaction, respectively. The introduction of click reaction effectively improved the durability in its practical daily use, realizing the true meaning of all-in-one structure. The results of Raman, FTIR and XRD confirmed the preparation route and chemical compositions. The SEM images and EDS mapping illustrated that a uniform and thin M-rGO-WPU film was attached tightly on cotton fiber. The conductive interconnected network in M-rGO-WPU/cotton imparted it with excellent electrical conductivity and enhanced mechanical properties. The EMI shielding effectiveness of M-rGO-WPU/cotton reached 48.1 dB, which was superior to that of rGO-WPU/cotton with a thickness of ∼1 mm at only 2 wt% nanofillers loadings. The high electromagnetic shielding performance of M-rGO-WPU/cotton was attributed to strong dielectric loss, more interfaces for multiple reflections and scattering. Furthermore, the performance related to practical application including high capability of heat transmission, durability, flexibility and processability were also investigated and showed its great potential in advanced EMI shielding applications.

    更新日期:2018-12-08
  • Graphene loaded with nano-Cu as a highly efficient foam interface material with excellent properties of thermal-electronic conduction, anti-permeation and electromagnetic interference shielding
    Chem. Eng. J. (IF 6.735) Pub Date : 2018-12-08
    Xianzhu Ye, Jing Hu, Bin Li, Min Hong, Yafei Zhang

    Strengthened conductive shielded graphene/nano-Cu/crosslinking polyurethane (CPU) foam with ultrahigh interfacial functions was newly fabricated, involving the use of nano-assembly-freeze extraction route. The 3D supported modified graphene-nano-Cu (GC) interface were analyzed and verified efficiently by FTIR, XRD, XPS spectra and SEM, TEM images. Towards the CPU foams doped with GC network, surface polarity was weakened efficiently, and the anti-permeation efficiency was significantly improved due to the special positive piling behaviors of nanosheets. The initial decomposition temperature (enhanced by ∼22.2 %) was efficiently delayed on account of heat transfer and doping protection. Thermal conductivity consistently fitted with modified Maxwell-Garnett method (D ∼ 5, Kp/Km ∼ 1000) was increased by ∼338% due to the collaborative formation of phonon-electron transmission network. More importantly, the electric conductivity was increased by orders of magnitude, along with the verification of 3D synergistic transmission network using percolation threshold. As compared to the pure CPU material, a maximum electromagnetic interference shielding (EMI) effectiveness of over 55 dB in the frequency range of 0-9 GHz was demonstrated on the interface with only ∼0.87 vol. % GC doping. All these suggest that the CPU foams simply doped with characteristic GC possesses a great potential to be used as lightweight, highly conductive, anti-penetrative and stable anti-interference materials.

    更新日期:2018-12-08
  • A New Contact Time Model for the Mechanistic Assessment of Local Heat Transfer Coefficients in Bubble Column Using Both the Four-Optical Fiber Probe and the Fast Heat Transfer Probe-Simultaneously
    Chem. Eng. J. (IF 6.735) Pub Date : 2018-12-08
    Moses Kagumba, Hayder Al-Naseri, Muthanna H. Al-Dahhan

    The purpose of this study is to analytically assess the local heat transfer coefficients by using the local bubble properties, which include the local gas holdup, bubble pass frequency, bubble chord length, and axial bubble velocity in a bubble column reactor. Therefore, for the first time, a combined probe that consists of a fast-response heat transfer coefficients probe and an advanced four-point optical probe was used for simultaneously measuring the heat transfer coefficients and the bubble properties, respectively. A new model, which has been developed, applied to estimate the contact time ( τ ) between the thin liquid film on the heating surface and the bulk liquid, which is one of the two parameters required in the mechanistic equation for determining the heat transfer coefficients. The experiments were conducted using a Plexiglas bubble column of 0.44 m diameter and 3.66 m height. Analytically, the consecutive film and the renewal mechanistic model of the unsteady-state surface have been used to calculate the rate and coefficients of the heat transfer. Results illustrate that the heat transfer coefficients is significantly affected by the local bubble properties and their distributions over the surface of the heat sensor. However, the contact time (τ) is a function for the local gas holdup and the bubble pass frequency. Thus, the variation in the local heat transfer coefficients with the contact time is due to the bubble pass frequency and the local gas holdup. A very good agreement, within 13 %, was found between the predicted and the experimental values of the heat transfer coefficients, even though the model overpredicts the heat transfer coefficients at all the evaluated conditions.

    更新日期:2018-12-08
  • Multiple probability principal component analysis for process monitoring with multi-rate measurements
    J. Taiwan Inst. Chem. E. (IF 3.849) Pub Date : 2018-12-07
    Le Zhou, Junghui Chen, Jing Jie, Zhihuan Song

    To obtain the informative enough data from the modern chemical processes, various sensors and measuring instruments have been applied. Among them, both the online measurements and offline laboratory analyser results are collected and used for multivariate statistical process monitoring purpose. Hence, it indicates that the obtained measurements indeed contain different sampling rates due to the different demands of the control systems and the equipment constraints. To handle the multi-rate process monitoring problem, it is desirable to effectively integrate the measurements with different sampling rates. In this paper, a multiple probability principal component analysis (MPPCA) model is proposed for efficient collection of data and the improvement of the performance on model prediction and process monitoring. In the proposed model, it has been derived as a general form for any multi-rate systems and the model parameters are calibrated by the expectation–maximization algorithm. Based on it, several statistics are constructed for different sampling rates in the process monitoring scenario. Finally, two case studies are presented to show the effectiveness of the proposed method.

    更新日期:2018-12-08
  • Hydrothermal synthesis of flower-like Na-doped α-Bi2O3 and improved photocatalytic activity via the induced oxygen vacancies
    J. Taiwan Inst. Chem. E. (IF 3.849) Pub Date : 2018-12-08
    Yanlin Huang, Jie Qin, Xuanxuan Liu, Donglei Wei, Hyo Jin Seo

    Na-doped α-Bi2O3 with a hierarchical flower-like shape was successfully prepared via a facile hydrothermal reaction. The samples consisted of well-crystalized nanoplates with smooth surfaces and a thickness of tens of nanometers. The phase formation was investigated via X-ray powder diffraction (XRD) patterns and structural refinements. The formations of oxygen vacancies were verified and its effects on the optical and photocatalysis were discussed. The band gap of α-Bi2O3 was narrowed via forming the local energy levels by oxygen vacancy defect complexes in the lattices. The photocatalytic activities on photo-degradation of Rhodamine B (RhB) were significantly improved. The effective photocatalysis was discussed on the improved visible-light response, band structure, and dynamic luminescence decay. The photocatalysis of Na-doped α-Bi2O3 was improved via the induced oxygen vacancies. The reported hydrothermal synthesis was advantageous approach to prepare α-Bi2O3 by considering the simplicity, low reaction temperature, no post-sintering, without using any template or surfactant, large-scale production, low cost, etc.

    更新日期:2018-12-08
  • Swelling reduction of polyvinylidenefluoride hollow fiber membrane incorporated with silicoaluminophosphate-34 zeotype filler for membrane gas absorption
    Sep. Purif. Technol. (IF 3.927) Pub Date : 2018-12-07
    N.A. Ahmad, C.P. Leo, A.L. Ahmad, M. Nur Izwanne

    CO2 gas absorption is important in fuel purification and carbon capture. By incorporating a porous membrane with a large surface area in membrane gas absorption (MGA) system, the CO2 transfer between feed gas and liquid absorbent can be greatly improved. However, the absorption flux usually drops in the long-term operation due to membrane wetting by the common liquid absorbent, amine. Membrane wetting can lead to membrane swelling which induce the growth of mass transfer resistance. In this work, silicoaluminophosphate-34 (SAPO-34) zeolite was incorporated into polyvinylidene fluoride (PVDF) hollow fiber membrane to reduce flux decline caused by membrane swelling. The membrane porosity and pore size increased with increasing SAPO-34 loading. Nevertheless, significant changes in water contact angle or liquid entry pressure were not shown. PVDF hollow fiber membrane incorporated with 3 wt% of SAPO-34 showed slightly higher CO2 absorption flux to PVDF hollow fiber membrane in MGA with distilled water as the absorbent. However, the CO2 absorption flux of this PVDF/SAPO-34 membrane was greatly improved of about 140 % higher than the CO2 absorption flux of the neat membrane when diethanolamine was used as the absorption. The CO2 absorption flux of PVDF hollow fiber membrane dropped about 60 % after 96 hours. Although these membranes showed a similar water contact angle after being wetted by water or amine, they swelled differently. PVDF hollow fiber membrane swelled nearly 71.0 % after being wetted by amine, but only swelled about 2 % after being wetted by water. The incorporation of SAPO-34 into PVDF hollow fiber membrane reduced swelling by amine, down to 47.7 %. The swelling reduction could be a major cause of absorption improvement shown by PVDF/SAPO-34 hollow fiber membrane in MGA using diethanolamine.

    更新日期:2018-12-08
  • Conversion of water-organic solution of sodium naphtenates into naphtenic acids and alkali by electrodialysis with bipolar membranes
    Sep. Purif. Technol. (IF 3.927) Pub Date : 2018-12-07
    Aslan Achoh, Victor Zabolotsky, Stanislav Melnikov

    The process of recovery of sodium naphtenates into naphtenic acids and sodium alkali using electrodialysis with bipolar membranes is investigated. The values of current efficiency for naphtenic acid and alkali, as well as energy consumption for the process, are determined. It is shown that the main problems with the development of electro-membrane technology for producing naphtenic acids from petroleum and petroleum products are associated with micelle formation of a mixture of naphtenic acids with sodium naphtenate in the pH = 6.5–8 range, which leads to a sharp increase in the viscosity and electrical resistance of solutions. Introduction of the cation-exchanger and sodium sulfate to the intermembrane space of naphtenthe salt chamber can significantly improve the technical and economic characteristics of the process - for example, the specific energy consumption decrease from 0.86 kWh∙L–1 down 0.38 kWh∙L–1, which is more than two times lower than the original three-chamber cell. At the same time, the production of naphtenic acids remains on the same level which is 17 L∙m-2∙h-1.

    更新日期:2018-12-08
  • Stepwise synthesis of oligoamide coating on a porous support: Fabrication of a membrane with controllable transport properties
    Sep. Purif. Technol. (IF 3.927) Pub Date : 2018-12-07
    Paramita Manna, Alberto Tiraferri, Marco Sangermano, Roy Bernstein, Roni Kasher

    Porous polymeric membranes are widely used in potable water purification, wastewater treatment, the food and pharmaceutical industries, and haemodialysis. However, producing specialized membranes with diverse transport properties is challenging. A method for fabricating membranes with controllable transport properties is described here by stepwise synthesis of aromatic oligoamide on a porous polymeric support. The use of aromatic oligoamide affords good water permeance due to its hydrophilic character. Alternate couplings of trimesoyl chloride and meta-phenylenediamine yielded an oligoamide dendrimer that was covalently bonded to the support. The water permeance and molecular weight cutoff (MWCO) of the synthesized membranes were controlled (with values of 4.6 to 543 L·m−2·h−1·bar−1 and 22.6 to 332 kDa, respectively) by adjusting the number of oligoamide synthesis cycles in the range of 2.5 – 20.5. The oligoamide membrane with 5.5 synthetic cycles showed a high rejection of the negatively charged rose bengal dye (95% rejection) with high flux (126.4 ± 4.2 L·m−2h−1 at 5.2 bar), as compared with other membranes reported in the literature. The fabricated membranes are potentially highly useful for the separation of macromolecules with specific ranges of molecular weight, for industrial separations that require membranes with tunable MWCO ranges, or for the separation of charged macromolecules.

    更新日期:2018-12-08
  • Hybrid electrostatic filtration systems for fly ash particles emission control. A review
    Sep. Purif. Technol. (IF 3.927) Pub Date : 2018-12-07
    A. Jaworek, AT. Sobczyk, A. Krupa, A. Marchewicz, T. Czech, L. Śliwiński

    The removal of submicron and nanoparticles from flue gases emitted by coal fired boilers is the subject of extensive studies in recent years. Electrostatic precipitators and fibrous filters are the most commonly used gas-cleaning devices for the removal of these particles in power plants and industry. However, the collection efficiency of electrostatic precipitators decreases for particles smaller than 1 micron. Fibrous filters provide higher filtration efficiency for particles of this size, but the pressure drop is higher, and additional energy is needed to supply the outlet fan. Recently, special attention of engineers has been given to hybrid constructions, which apply electrostatic fields and forces in order to improve the performances of bag filters. There are three types of such solutions, which have been investigated in the literature: (1) electrically energized filter, in which fibres of the filter are energized by an electric field; (2) hybrid electrostatic filter, which applies electrostatic charging of particles before their filtration by bag filter; and (3) hybrid electrostatic precipitator, which uses a conventional electrostatic precipitator for the removal of coarse particles, and a subsequent bag filter for the removal of fine particles leaving the precipitator. All of these constructions allow the collection efficiency for PM2.5 particles to be increased and the pressure drop across the bag filter to be reduced. In this paper, various hybrid electrostatic filtration systems have been reviewed and their performances compared with respect to collection efficiency, pressure drop and dust cake dislodging.

    更新日期:2018-12-08
  • Reduced Thermal Rearrangement Temperature via Formation of Zeolitic Imidazolate Framework (ZIF)-8-based Nanocomposites for Hydrogen Purification
    Sep. Purif. Technol. (IF 3.927) Pub Date : 2018-12-08
    Susilo Japip, Sugiarto Erifin, Tai-Shung Chung

    Thermally rearranged polymers are a class of heterocyclic microporous polymers generated by in situ thermal rearrangement (TR) of ortho-hydroxy polyamides or polyimides at elevated temperatures to produce polybenzoxazole (PBO). Poly(hydroxyamide) (PHA) was selected as a model polymer to generate amide-derived PBO (APBO) owing to its lower TR temperature. A nano-size zeolitic imidazolate framework of ZIF-8 was synthesized and incorporated into the PHA matrix to form PHA-ZIF8 nanocomposites. Due to the presence of ZIF-8 inside the PHA matrix, interchain interactions in the PHA matrix may be inhibited that results in a reduced TR temperature for PHA conversion into APBO. Differential scanning calorimetry (DSC) confirmed that the TR temperature of PHA-ZIF8 nanocomposites decreases as a function of ZIF-8 loading. In addition, the conversion of PHA into APBO and the structural integrity of ZIF-8 before and after TR were visualized by Fourier-transform infra-red (FTIR) spectroscopy and X-ray diffractometer (XRD), respectively. Subsequent measurements of gas transport properties of both PHA-ZIF8 and APBO-ZIF8 nanocomposites revealed that the synergistic amalgamation of TR and formation of nanocomposites can boost hydrogen separation performance, particularly H2/CH4, of APBO-ZIF8-35% close to the 2008 upper-bound.

    更新日期:2018-12-08
  • Hydrogen Embrittlement of a Quenching and Partitioning Steel during Corrosion and Zinc Electroplating
    Mater. Sci. Eng. A (IF 3.414) Pub Date : 2018-12-07
    T. Mehner, I. Scharf, P. Frint, F. Schubert, B. Mašek, M.F.-X. Wagner, T. Lampke

    Quenching and partitioning (Q&P) treatments result in promising mechanical properties of advanced high-strength steels. However, recent studies indicate that Q&P steels are very susceptible to hydrogen embrittlement (HE). Using slow strain-rate tests, the effects of hydrogen charging in different media without and with recombination poison were investigated for Fe-0.38C-1.92Si-0.66Mn-1.39Cr in quenched and tempered as well as Q&P conditions. In addition, corrosion tests and Zn electroplating of tensile specimens were performed. In both heat-treatment states, it was found that the intensified hydrogen-charging conditions using a recombination poison strongly impact the result of HE investigations: HE only occurs when a recombination poison is present. In addition, the negative influence of hydrogen formed during Zn electroplating can be limited by using proper electrolytes and electrical parameters. This allows keeping the HE susceptibility of the Q&P steel low in practical applications when recombination poisons are absent.

    更新日期:2018-12-08
  • Algal Extracts Based Biogenic Synthesis of Reduced Graphene Oxides (rGO) with Enhanced Heavy Metals Adsorption Capability
    J. Ind. Eng. Chem. (IF 4.841) Pub Date : 2018-12-07
    Shahbaz Ahmad, Aftab Ahmad, Sikandar Khan, Shujaat Ahmad, Idrees Khan, Shah Zada, Pengcheng Fu

    Efficient reduction of GO was performed, using cellular extracts of three algal strains. The rGO were characterized by SEM, TEM, UV-Visible spectroscopy, XRD, FTIR, Raman spectroscopy, Zeta potential and redox potentials. The rGO were then used as decontaminating agents for heavy metals (Cu and Pb), in waste water. GO reduced via JSC-1 have removed up to 93% Cu and 82% Pb (adsorption capacity of 93 mg.g−1 and 82 mg.g−1, respectively), by 211-9a have removed 74% (74 mg.g−1) Cu and 89% (89 mg.g−1) Pb, while by 211-11n have adsorbed 91% (91 mg.g−1) Cu and 95% Pb (95 mg.g−1), within 30 min.

    更新日期:2018-12-08
  • Microstructural characterization and mechanical behavior of an AgAlNbTiZn complex composition alloy produced using powder metallurgy (P/M)
    Mater. Sci. Eng. A (IF 3.414) Pub Date : 2018-12-07
    João Felipe Q. Rodrigues, Diego Costa, Rodrigo J. Contieri, Wislei R. Osório, Ausdinir D. Bortolozo

    This investigation is focused on a complex composition AgAlTiNbZn alloy manufactured by using the powder metallurgy (P/M) route. Four distinctive heat-treating temperatures are used (i.e. 580, 750, 850, 1000 oC). X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used in order to characterize the resulting microstructural array obtained. Although, theoretical thermodynamic parameters from literature are used, a solid solution is not constituted. It is found that TiAl intermetallics are neighboring the dispersed Nb particles. Besides, they are also embedded into an AgZn matrix. The examined AgAlNbTiZn alloy constitutes a complex multicomponent alloy (CCA). Its compressive strength is increased up to a heat-treating at 750 oC and decreased when at 850 and 1000 oC is carried out. A controlling of the second phase permits to preprogram the resulting mechanical strength of the alloy/composite examined.

    更新日期:2018-12-08
  • A Tailored Molecular Imprinting Ratiometric Fluorescent Sensor Based on Red/Blue Carbon Dots for Ultrasensitive Tetracycline Detection
    J. Ind. Eng. Chem. (IF 4.841) Pub Date : 2018-12-07
    Xiqing Liu, Tao Wang, Wenjuan Wang, Zhiping Zhou, Yongsheng Yan

    The molecular imprinting ratiometric fluorescence sensor has exhibited great potential in biological and environmental detection because of the combination between the excellent selectivity of molecular imprinting technique and outstanding robustness of ratiometric measurement methods On this basis, two kinds of different well-resolved wavelengths and high-fluorescent carbon dots (CDs) were prepared by various solvent extraction using osmanthus fragrans leaves as carbon source. Then the ratiometric fluorescence sensor (MIPs@rCDs/bCDs@SiO2) has been constructed by the obtained CDs which the red-emission CDs (rCDs) were used to responsive signal and the blue-emission CDs (bCDs) was served as reference signal and applied for highly selective and excellent sensitive detection of tetracycline (TC). Under optimum conditions, the ratiometric fluorescence MIPs@rCDs/bCDs@SiO2 sensor has also exhibited lower detection limit of 1.19 nM and the linear range of 0–50 nM. The ratiometric fluorescence sensor was further successfully employed to the determination of TC in water samples gathered from local river water and tap water, indicating its great worth toward water sample analysis in complicated environments.

    更新日期:2018-12-08
  • Designing Metal Oxide-Vertical Graphene Nanosheets Structures for 2.6 V Aqueous Asymmetric Electrochemical Capacitor
    J. Ind. Eng. Chem. (IF 4.841) Pub Date : 2018-12-07
    Subrata Ghosh, S.R. Polaki, Gopinath Sahoo, En-Mei Jin, M. Kamruddin, Jung Sang Cho, Sang Mun Jeong

    The asymmetric electrochemical capacitor was realized by MnO2/Vertical graphene nanosheets (VGN) and Fe2O3/VGN as positive and negative electrodes, respectively. The surface of VGN skeleton is independently decorated with MnO2 having sponge gourd-like morphology and Fe2O3 having nanorice like morphology. Both the electrodes have shown around 250 times higher charge-storage capacity than the bare VGN (0.47 mF/cm2) with the specific capacitance of 118 (MnO2/VGN) and 151 mF/cm2 (Fe2O3/VGN). The fabricated asymmetric device exhibited a specific capacitance of 76 mF/cm2 and energy density of 71 μWh/cm2 with an excellent electrochemical stability up to 12000 cycles, over a potential window of 2.6 V.

    更新日期:2018-12-08
  • The influence of stacking fault energy on mechanical properties of Cu-Al-Zn alloys processed by surface mechanical attrition treatment
    Mater. Sci. Eng. A (IF 3.414) Pub Date : 2018-12-07
    Lifang Meng, Zheng Zhang, Yueling Zhang, Jinxu Zhang, Xu Yang, Hongliang Gao, Baipo Shu, Xinkun Zhu

    Cu-5.5Al-4.5Zn, Cu-1.9Al-23.9Zn and Cu-1.1Al-2.6Zn (in wt.%) alloys with different stacking fault energy (SFE) were prepared by means of surface mechanical attrition treatment (SMAT). Subsequently, gradient structure (GS) was generated in the Cu-Al-Zn alloys, which significantly improved the mechanical properties of the alloys. The influence of SFE on mechanical properties was systematically investigated. The strength of the annealed Cu-Al-Zn alloys increased with the decrease of SFE. The uniform elongation (UE) did not decline with increasing SMAT time in the Cu-5.5Al-4.5Zn alloy. Our results indicate an exceptional combination of high strength and ductility in the Cu-5.5Al-4.5Zn (lowest SFE) alloy processed by SMAT.

    更新日期:2018-12-08
  • Effects of Cu loading and zeolite topology on the selective catalytic reduction with C3H6 over Cu/zeolite catalysts
    J. Ind. Eng. Chem. (IF 4.841) Pub Date : 2018-12-07
    Kyungseok Lee, Hidenori Kosaka, Susumu Sato, Toshiyuki Yokoi, Byungchul Choi, Daesuk Kim

    The objective of this study is to investigate the catalytic performance of Cu-zeolite catalysts supported on various types of zeolites (chabazite, MFI, and BEA) for selective catalytic reduction with C3H6. 2Cu/ZSM-5 exhibited a nearly 70% de-NOx performance at 360 °C, Cu/SSZ-13 and Cu/BETA exhibited less than 60%. The loading of Cu also exhibited different de-NOx performances, which were related to the chemical states of Cu. The isolated Cu2+ ion was favorable to the NOx reduction compared to the bulk CuOx species. The effects of O2, CO2 concentrations and hydrothermal aging were investigated for the 2Cu/ZSM-5 catalyst.

    更新日期:2018-12-08
  • Quantitative description between pre-fatigue damage and residual tensile properties of P92 steel
    Mater. Sci. Eng. A (IF 3.414) Pub Date : 2018-12-08
    Xiaowei Wang, Wei Zhang, Junyan Ni, Tianyu Zhang, Jianming Gong, Magd Abdel Wahab

    The alteration of material tensile properties is inevitable after material subjects to irreversible damage. This paper is devoted to quantify the influence of pre-fatigue damage on the residual tensile properties of P92 steel. Various pre-fatigue tests followed by uniaxial tensile tests are conducted at 650 °C. Results indicate that higher strain amplitude of pre-fatigue loading leads to reduction in residual yield stress and ultimate tensile stress (UTS). In addition, the evolution of yield stress and UTS in terms of pre-fatigue lifetime fraction shows two stages, namely initial rapid degradation stage and linear decreasing stage. The microstructure observation manifests that the growth of martensite lath width and the decline of dislocation density during pre-fatigue loadings contribute to the degradation of subsequent tensile strength. However, the reduction in dislocation density plays a dominant role. Furthermore, a pre-fatigue damage definition is proposed. The variations of residual yield stress and UTS can be described linearly with respect to the defined pre-fatigue damage. The newly proposed linear relationships are convenient for practical application.

    更新日期:2018-12-08
  • Selective electron beam melting of NiTi: microstructure, phase transformation and mechanical properties
    Mater. Sci. Eng. A (IF 3.414) Pub Date : 2018-12-08
    Quan Zhou, Muhammad Dilawer Hayat, Gang Chen, Song Cai, Xuanhui Qu, Huiping Tang, Peng Cao

    Recent years have witnessed extensive investigations of additively manufactured NiTi alloys using laser-source techniques. This study reports a selective electron beam melting process to make Ni-rich NiTi parts using the plasma rotating electrode processed pre-alloyed NiTi powder. Microstructures of the as-printed NiTi samples were investigated, including micro-morphology, phase constituent and texture. Chemical compositions (primarily oxygen and nickel) and martensitic transformation temperatures were compared between the in house made NiTi powders and as-printed NiTi samples. X-ray diffraction results show that the as-printed samples exhibit a dominant austenitic B2 phase and a minor in situ formed Ni4Ti3 phase. The as-printed samples demonstrate a strong B2 (001) orientation texture along the building direction. Differential scanning calorimetry results show asymmetric phase transformations: a two-step of B2 → R → B19’ phase transformation during cooling but a one-step B19’ → B2 transformation during heating. Excellent superelasticity and large reversible strain have been observed. The as-printed NiTi samples achieve a fracture tensile stress of 1411.0 ± 59.3 MPa and an elongation of 11.8 ± 0.9 %. The observed tension-compression asymmetry has been also discussed.

    更新日期:2018-12-08
  • Strain rate sensitivity behavior of a structural steel during low-cycle fatigue investigated using indentation
    Mater. Sci. Eng. A (IF 3.414) Pub Date : 2018-12-08
    Ngoc-Vinh Nguyen, Thai-Hoan Pham, Seung-Eock Kim

    In this study, a series of experiments consisting of low-cycle fatigue, constant loading rate indentation, creep indentation experiments, optical microscopy examination, and transmission electron microscopy were performed to investigate the strain rate sensitivity behavior of SS400 structural steel under cyclic loading conditions. 400 indentations were conducted in the displacement control mode at different strain rate indentations varied from 0.02 s-1 to 0.2 s-1 and the effects of strain rate indentation on mechanical properties were investigated on four fatigue failure specimens. An analytical method was used to estimate mechanical properties of the structural steel from the loading/unloading curves. The results indicated that the yield strength and the strain hardening exponent strongly depended on both the strain rate indentation and the strain amplitude. Yield strength and strain hardening exponent tended to increase when the strain amplitude increased. The strain rate sensitivity (SRS) was also determined from the yield strength and the creep indentation data, and the dependency of the strain rate sensitivity on the strain amplitude level was examined. The results showed that the strain rate sensitivity exhibited decrease almost linearly when the strain amplitude increased from 0.4% to 1.0%. The results of the present study were used to assess and understand the strain rate sensitivity behavior of SS400 structural steel during low-cycle fatigue.

    更新日期:2018-12-08
  • Mechanical anisotropy and local ductility in transverse tensile deformation in hot rolled steels: The role of MnS inclusions
    Mater. Sci. Eng. A (IF 3.414) Pub Date : 2018-12-08
    Meng Wu, Wen Fang, Ruo-Meng Chen, Bo Jiang, Hai-Bo Wang, Ya-Zheng Liu, Han-Ling Liang

    The mechanical anisotropy and effects of MnS inclusions configuration on the local ductility in hot rolled bars with 0.03% sulfur were experimentally investigated and statistically regression analyzed. Results show that the elongation and reduction of area decline significantly as the angle between the gauge length and the transverse direction decreases, while the tensile strength and yield strength vary little. The reduction of area in transverse tensile tests of various rolled bars ranges widely from 6.5% to 38.1% and the differences in engineering stress–strain curve profile are mainly reflected in the local deformation stage. MnS inclusions configuration in the surface adjacent to fracture were classified into three types according to the morphology and three-dimensional distribution. When the type of MnS transitions from C to A to B, the reduction of area decreases obviously and area of ribbon-like fractures where most local deformation performs declines as well. Multiple linear regression of the parameters of MnS inclusions shows that the reduction of area is more sensitive to the length of single MnS inclusion or aggregation of tiny MnS inclusions and the local density of MnS inclusions. Voids in matrix tends to nucleate between the parallel MnS inclusions and along the line connecting two MnS inclusions with rounded or blunt tips and then grow and link up to form cracks. Besides, cracks can also be directly induced by the sharp tips of tiny MnS inclusions. In conclusion, the aggregated tiny MnS inclusions of type B should be avoided and the evenly distributed spindle-shaped MnS inclusions of type C are expected in steels requiring favorable transverse mechanical properties.

    更新日期:2018-12-08
  • Mechanochemical-Assisted Extraction of Active Alkaloids from Plant with Solid Acids
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-07
    Shuling Wang, Rui Zhang, Xiaoyu Song, Mengmeng Wei, Tian Xie, Jun Cao
    更新日期:2018-12-08
  • ReOx/AC-Catalyzed Cleavage of C–O Bonds in Lignin Model Compounds and Alkaline Lignins
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-07
    Bo Zhang, Zaojuan Qi, Xinxin Li, Jianwei Ji, Wenhao Luo, Changzhi Li, Aiqin Wang, Tao Zhang
    更新日期:2018-12-08
  • Hybrid Microwave Annealing for Fabrication of More Efficient Semiconductor Photoanodes for Solar Water Splitting
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-07
    Ju Hun Kim, Youn Jeong Jang, Sun Hee Choi, Byeong Jun Lee, Min Hee Lee, Jae Sung Lee
    更新日期:2018-12-08
  • Redox-Mediated Shape-transformation of Fe3O4 Nanoflake to Chemically Stable Au-Fe2O3 Composite Nanorod for High-Performance Asymmetric Solid-State Supercapacitor Device
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-07
    Siddheswar Rudra, Arpan Kumar Nayak, Sudipta Koley, Rishika Chakraborty, Pradip Kumar Maji, Mukul Pradhan

    Development of a stable and highly active metal oxide based electrochemical supercapacitor is a major challenge. Herein, we report Au-Fe2O3 nanocomposite having tiny amount of gold (3 atomic % Au) by employing a simple redox-mediated synthetic methodology using modified hydrothermal system. Structural and morphological studies of the synthesized Au-Fe2O3 nanocomposite have been performed both experimentally (XRD, IR, Raman, XPS, TEM and FESEM analyses) and theoretically (WIEN2K). A probable dissolution-nucleation-recrystallization growth mechanism has been suggested to ex-plain the morphological transformation from Fe3O4 nanoflake to Au-Fe2O3 nanorod. We have observed the superior chemi-cal stability of Au-Fe2O3 nanocomposite in acidic medium due to composite formation. The electrochemical measurement of the synthesized Au-Fe2O3 nanocomposite exhibits specific capacitance of ~570 F g-1 at the current density of 1 A g-1 in 0.5 M H2SO4 electrolyte. The result is superior compared to the mother component i.e., Fe2O3 (138 F g-1) under identical con-dition. It is credited to its higher specific surface area and composite effect. Theoretically, decrease in band gap associated with increase in conductivity support the superiority of Au-Fe2O3 nanocomposite compared to the mother compound i.e., Fe2O3. In addition, electrochemical kinetic analysis showed that the charge-storage mechanism is mostly from a dominant capacitive process (78 % at 1.5 mV s-1). Solid-state asymmetric supercapacitor device has been fabricated using synthesized Au-Fe2O3 composite nanorod as positive and activated carbon as negative electrodes. The asymmetric solid-state device exhibits maximum energy density of 34.2Wh kg-1 and power density of 2.73 kW kg-1 at current densities 1 A g-1 and 10 A g-1, respectively. Thus, the synthesized nanocomposite shows excellent activity as a supercapacitor with long term durability (91% capacitance retention) up to 5000 cycles even in acidic medium.

    更新日期:2018-12-08
  • Regenerated casein-nanocellulose composite fibers via wet spinning
    ACS Sustainable Chem. Eng. (IF 6.14) Pub Date : 2018-12-07
    Oleksandr Nechyporchuk, Tobias Köhnke

    Development of sustainable bio-based fibers is required to displace their fossil-based counterparts, e.g. in textile, non-woven or composite applications. Regenerated protein fibers have a potential to provide such an opportunity if their mechanical properties are improved. Herein, we study for the first time the use of nanocellulose as reinforcement in regenerated protein fibers produced using wet spinning. The influence of cellulose nanocrystals (CNC) incorporated in regenerated casein fibers are investigated in terms of mechanical and morphological properties. Additionally, we study the influence of different chemical cross-linking conditions on fiber properties. Incorporation of CNC (up to 37.5 wt%) results in continuous increase of fiber Young’s modulus (up to two-fold) in dry state. Both maximum and breaking tenacity of dry fibers are also enhanced, with a maximum increase observed at 7.0–10.5 wt% CNC content. When testing after being wetted, both breaking tenacity and Young’s modulus of the composite fibers decrease, which is likely due to weakening of hydrogen bonds between CNC in the presence of water. We also demonstrate that the presence of salt during chemical cross-linking is crucial to produce intact and separated fibers in the yarn.

    更新日期:2018-12-08
  • Bifunctional imidazole‐PTSA deep eutectic solvent for synthesizing long‐chain ester IBIBE in reactive extraction
    AlChE J. (IF 3.326) Pub Date : 2018-12-08
    Hao Qin; Zhen Song; Qian Zeng; Hongye Cheng; Lifang Chen; Zhiwen Qi

    The traditional production of long‐chain organic esters like isobutyl isobutyrate (BIBE) suffers from severe problems due to the homogenous catalyst in process and complex system thermodynamics. In this work, an innovative bifunctional deep eutectic solvent (DES) is introduced, playing as both reaction catalyst and extraction solvent, to intensify the esterification process. The DES was formed by imidazole (Im) and p‐toluenesulfonic acid (PTSA), which was for the first time found acid–base tunable, represented by weak basic DES [3Im:PTSA] and strong acidic DES [Im:2PTSA]. The formation mechanisms of [3Im:PTSA] and [Im:2PTSA] were illustrated by Fourier‐transform infrared spectroscopy (FTIR) and COnductor‐like Screening MOdel for Real Solvent (COSMO‐RS) combined with the Im‐PTSA phase diagram. The dual functions of the acidic [Im:2PTSA] in reactive extraction were evaluated by σ‐potential analysis and esterification experiments. The high conversion, easy product separation, and good solvent reusability confirm the excellent catalytic and solvent effect of [Im:2PTSA]. © 2018 American Institute of Chemical Engineers AIChE J, 2018

    更新日期:2018-12-08
  • Kinetic modeling of methanol to olefins process over SAPO‐34 catalyst based on the dual‐cycle reaction mechanism
    AlChE J. (IF 3.326) Pub Date : 2018-12-08
    Xiaoshuai Yuan; Hua Li; Mao Ye; Zhongmin Liu

    A kinetic model for methanol to olefins (MTO) process over SAPO‐34 catalyst was established based on the dual‐cycle reaction mechanism. Simplifications were made by assuming olefins‐based cycle as virtual species S, and aromatics‐based cycle as R, where the former mainly accounts for the production of higher olefins, while the latter for lower olefins. Transformation of S to R was considered with the participation of methanol and olefins. Meanwhile, a phenomenological deactivation model was developed to account for the deactivation process. With the proposed model, the evolution of methanol conversion and product selectivity with time on stream could be predicted, and key reaction characteristics, such as the autocatalytic nature of the reaction, could also be captured due to its mechanism‐based nature. Further simulations of MTO reactors at different scales validated the robustness and applicability of the current model in MTO process development and optimization. © 2018 American Institute of Chemical Engineers AIChE J, 2018

    更新日期:2018-12-08
  • Conversion of saline waste-water and gaseous carbon dioxide to (bi)carbonate salts, hydrochloric acid and desalinated water for on-site industrial utilization
    React. Chem. Eng. (IF 4.641) Pub Date : 2018-11-20
    Saad Dara, Arman Bonakdarpour, Meghan Ho, Rubenthran Govindarajan, David P. Wilkinson
    更新日期:2018-12-08
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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