Long-term activity of a CuO/SBA-15 type SOx adsorbent: impact of the regeneration step Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-11 Marc Berger, Habiba Nouali, Sophie Dorge, David Habermacher, Emmanuel Fiani, Matthieu Vierling, Michel Molière, Cornelius Schönnenbeck, Jean-François Brilhac, Joël Patarin
Sulphur oxides (SOx) are a major air pollutant regulated by European legislations. To date, most efficient DeSOx technologies are energy-intensive and produce high amounts of waste. Thus CuO/SiO2 adsorbents represent a viable SOx trapping alternative. However, their large-scale development is hampered by the sintering of the active phase over multiple adsorption and regeneration cycles, leading to the progressive decrease in performance of the adsorbent. In this work, a CuO/SBA-15 adsorbent was assessed as a SOx trap material and different regenerations methods were evaluated with the aim to limit that sintering phenomenon and assure the conservation of SO2 adsorption performance over several adsorption and regeneration cycles. It was found that a regenerative treatment under 0.5 vol.% of H2 in N2 can be carried out either at 300°C or 400°C, without any substantial loss of SO2 adsorption performance over 8 successive cycles. A diffusional-limited decomposition mechanism describes the different steps of the regeneration stage, especially the kinetics of the regeneration step that is governed by the H2 transport within the porosity. The SO2 adsorption process was not the main degradation path of the textural properties of the adsorbent but the latter are strongly affected by the thermal effect associated to the adsorption and regeneration cycling.
Effects of salinity on the nitrogen removal efficiency and bacterial community structure in fixed-bed biofilm CANON bioreactors Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-11 M.J. García-Ruiz, A. Castellano-Hinojosa, J. González-López, F. Osorio
The discovery of anaerobic ammonium oxidation processes led to the development of innovative nitrogen removal technologies, which are more cost-effective and environmentally friendly than conventional activated sludge systems. In this study, the bacterial community structure was determined as well as the nitrogen removal efficiencies in four fixed-bed biofilm bioreactors, working under different salt concentrations (0, 3, 25, and 45 g L−1 of sodium chloride (NaCl)) and at hydraulic retention times (HRT) of 6 and 12 h. The influent total nitrogen concentration was 250 mg L−1. The results showed a clear inhibition in the nitrogen removal capacity of the process that was directly related to the salt concentration in the influent, most likely due to changes in the bacterial community structure; increases in the NaCl concentration provoked the inhibition of Candidatus Brocardia and Nitrosomonas, whereas heterotrophic phylotypes such as Marinobacter proliferated. An evident adaptation of the anammox microorganisms at 3 g NaCl L−1 was observed, whereas ammonia and nitrite oxidizing bacteria drastically decreased at 25 and 45 g NaCl L−1. Total nitrogen efficiencies for 6h of HRT were 87.68, 64.25, 38.79, and 19.74%, for 0, 3, 25, and 45 g NaCl L−1, respectively. No significant effects were detected on the performance of the bioreactors and bacterial diversity under different HRT. Our study may be useful for the implementation of CANON systems at real-scale, by increasing the knowledge on the bacterial community at different NaCl concentrations and the performance of this novel technology for saline wastewater treatment.
Chemical, Microbial and Toxicological Assessment of Wastewater Treatment Plant Effluents during Disinfection by Ozonation Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-11 Deniz Nasuhoglu, Siavash Isazadeh, Paul Westlund, Sarah Neamatallah, Viviane Yargeau
Bioreactor design for enzymatic hydrolysis of biomass under the biorefinery concept Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-11 Marcela Sofía Pino, Rosa M. Rodríguez-Jasso, Michele Michelin, Adriana C. Flores-Gallegos, Ricardo Morales-Rodriguez, José A. Teixeira, Héctor A. Ruiz
The dependence on non-renewable resources, particularly fossil fuels, has awaken a growing interest in research of sustainable alternative energy sources, such as bioethanol. The production of bioethanol from lignocellulosic materials comprises three main stages, starting with a pretreatment, followed by an enzymatic hydrolysis step where fermentable sugars are obtained for the final fermentation process. Enzymatic hydrolysis represents an essential step in the bioethanol production, however there are some limitations in it that hinders the process to be economically feasible. Different strategies have been studied to overcome these limitations, including the enzyme recycling and the utilization of high solids concentrations. Several investigations have been carried out in different bioreactor configurations with the aim to obtain higher yields of glucose in the enzymatic hydrolysis stage; however, the commonest are Stirred Tank Bioreactors (STBR) and Membrane Bioreactors (MBR). In general, the key criteria for a bioreactor design include adequate mass transfer, low shear stress, and efficient mixing that allows the appropriated interaction between the substrate and the enzyme. Therefore, this review will address the main aspects to be considered for a bioreactor design, as well as, the operational conditions, some characteristics and mode of operating strategies of the two main bioreactors used in the enzymatic hydrolysis stage. Moreover, two types of pneumatically agitated bioreactors, namely bubble column and gas-lift bioreactors, are discussed as promising alternatives to develop enzymatic saccharification due to their low energy consumption compared with STBR.
Kinetics of coupling cracking of butene and pentene on modified HZSM-5 catalyst Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-10 Jianwen Li, Tao Li, Hongfang Ma, Qiwen Sun, Chunzhong Li, Weiyong Ying, Dingye Fang
The cracking of butene and pentene is an effective route for MTO process to sufficiently utilize these olefin byproducts. Butene and pentene can be efficiently converted to propylene and ethylene over HZSM-5 catalyst modified by Fe and P. In the coupling cracking of butene and pentene, butene mainly cracked through bimolecular pathway, while pentene cracked via both monomolecular and bimolecular pathways. Moreover, propylene was an intermediate product and might involve other type reactions besides cracking. Based on the effect of operating conditions, a six-lump (butene, pentene, propylene, ethylene, C1-5 alkanes and C6+ hydrocarbons) kinetic model is proposed for the coupling cracking of butene and pentene. Different cracking mechanisms were taken into account, and different reaction orders were obtained for reaction steps in the kinetic model. The experimental data were measured in an isothermal fixed-bed reactor under a wide range of operating conditions (at 490-610 °C; space time of 0.93-4.67 (g of catalyst) h (mol CH2)-1; steam ratio of 0.18-0.9 (g of steam) (g of feed)-1 range), and the kinetic parameters were estimated through Levenberg-Marquardt algorithm. A good parity between calculated and experimental data was attained, indicating the applicability of the model to quantify the distribution of product lumps.
Catalytic decomposition of HCN on copper manganese oxide at low temperatures: performance and mechanism Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-10 Yingjie Li, Huai Yang, Yuechao Zhang, Jing Hu, Jianhong Huang, Ping Ning, Senlin Tian
The Development of innovative treatment technology for HCN at low temperatures is vital for the control of HCN pollution. Here, a copper manganese oxide (Cu-Mn-O) catalyst was prepared for the decomposition of HCN at temperatures from 80 to 200 °C. The results showed that the Cu-Mn-O catalyst exhibited excellent catalytic performance for HCN conversion. X-ray photoelectron spectroscopy analysis revealed that Mn3+ manifested highly catalytic activity and was largely responsible for HCN decomposition. The N-contained products of HCN contained NH3, NO/NO2, N2O, and N2, thereby suggesting the concurrent catalytic oxidation and hydrolysis during HCN decomposition on the catalyst. The catalytic oxidation mechanism characterized by in situ diffuse reflectance infrared Fourier transform manifested that four N-contained intermediates (i.e., -CN, -NH2, =NH and -NCO) were produced; subsequent the oxidation of these intermediates resulted in the formation of final product and/or oxidative species NO+. The reaction of NO+ with the N-contained intermediates also generated the final conversion products. Catalytic intermediate formamide plays a critical role in the hydrolysis of HCN, and its hydrolysis leads to the formation of NH3. Multiple cycle experiments demonstrate the long-term stability of the Cu-Mn-O catalyst. These results indicate that catalytic decomposition of HCN based on the Cu-Mn-O catalyst at low temperatures may be an efficient approach for the treatment of tail gases containing HCN.
Closing the cycle: phosphorus removal and recovery from diluted effluents using acid resistive membranes Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-10 O. Nir, R. Sengpiel, M. Wessling
New regulations in many developed countries call for a significant reduction in phosphorus concentration for effluents released to the environment. At the same time, recovery of phosphorus - a non-renewable resource used mainly as fertilizer - from anthropogenic waste is extensively studied and bolstered as a crucial component in maintaining future food security. Thus far studies on phosphorus recovery mainly focused on concentrated streams, although diluted effluents such as treated wastewater often contain a significant portion of the phosphorus mass. Here we propose a new approach for the simultaneous removal and recovery of phosphorus from diluted effluents using a membrane characterized by high phosphate rejection and acid resistance. High P rejection allows for the concentration of phosphorus in the retentate until recoverable calcium-phosphate precipitants are formed, while acid resistance enables a simple and effective chemical cleaning of the membrane. Factors affecting the removal and recovery of phosphorus during filtration are studied here experimentally and through thermochemical modeling. CaCO3 precipitation in the retentate resulted in severe scaling, whereas calcium-phosphate precipitated mostly in the bulk, resulting in colloidal fouling which was manageable by maintaining sub-critical permeate flux. Selective Ca-P precipitation is feasible via pH adjustments, requiring very little acid addition as shown through thermochemical modeling. Calcium-phosphate deposits were easily removed from the feed channel using acid-cleaning, and the permeate flux was completely restored. Furthermore, phosphorus removal and recovery by nanofiltration was shown to require less operating expenses compared to a more conventional approach comprising P removal by ferric chloride addition and its subsequent recovery from incinerated sludge. Our results therefore demonstrate the potential of this new approach as a step forward towards closing the anthropogenic phosphorus cycle.
Novel Process for the exergetically efficient recycling of chlorine by gas phase electrolysis of hydrogen chloride Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-10 Simon Bechtel, Tanja Vidakovic-Koch, Kai Sundmacher
Due to the steadily increasing production capacities of polycarbonates and polyurethanes, the volume of hydrogen chloride (HCl), which emerges as byproduct from these processes, is experiencing a significant growth. Owing to the oversaturation of the market for HCl and hydrochloric acid, the question on how to utilize this byproduct in a sustainable and energy-efficient way is becoming more and more important. The oxidation of HCl to chlorine, which can be redirected as an educt to these above mentioned processes, offers a feasible solution to this problem and can be carried out either heterogeneously catalyzed at high temperatures or through electrolysis. Up to now, the most energy-efficient industrially employed electrochemical variant is the Bayer UHDENORA process, based on aqueous hydrochloric acid as a feed stock. The major objective of this work is to propose a novel electrochemical process utilizing HCl as a gaseous reactor feed in order to significantly reduce the electrical energy demand of the reactor combined with new and more energy-efficient subsequent separation sequences. For this purpose, flowsheet simulations of the Bayer UHDENORA process and two novel process variants based on the gas phase reactor and two different separation sequences were carried out and followed by a detailed exergy analysis. The analysis shows significant exergetic savings of up to 38 % in this novel process variants compared to the Bayer UHDENORA process, including not only the electrochemical reactor but also the subsequent separation steps. The novel process therefore allows for a more sustainable and energy-efficient production of the base chemical chlorine and, contrary to the heterogeneously catalyzed high temperature process, for the utilization of electrical energy from advancing renewable sources like wind and sun.
Impact of diffusion at the gas/liquid interface on deep hydrodesulfurization of fluid catalytic cracking naphtha Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-10 Lei Wang, Deren Fang, Yisen Wang, Hui Tian, Jie Liu, Wanzhong Ren
For fluid catalytic cracking naphtha, there exists a complex co-existing gas-liquid-solid three-phase system in the catalyst bed under deep hydrodesulfurization (HDS) conditions representative of industrial practice. The system is extremely crucial and could influence and even determine the finished HDS reaction result. The paper reports that owing to the diffusion at the gas/liquid interface of the above system, thiophene rather than slow-reacting benzothiophene and its alkylated derivatives remains in the final product, which is against with common-sense knowledge about the relative reactivity of sulfur compounds. Two designed experiments which investigate impacts of solvents and sulfur-containing compounds under different temperatures further corroborate the above conclusion. Meanwhile, they reveal that elimination of the diffusion through making gas/liquid two phases into one gas or liquid phase effectively improves the efficiency of desulfurization even under the same reaction conditions. It could be concluded that for the deep HDS reaction, diffusion at the gas/liquid interface is the rate-determining step of whole reaction, which is also proved by the resulting data under conditions (production of Euro-5 gasoline).
Adsorption/Reduction of Nitrogen Dioxide on Activated Carbons: Textural Properties versus Surface Chemistry - A Review Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-10 Mejdi Jeguirim, Meriem Belhachemi, Lionel Limousy, Simona Bennici
Activated carbons are promising materials for nitrogen dioxide adsorption. The synthesis, the characterization of activated carbons and their adsorption performance toward nitrogen dioxide are here reviewed. Particular attention is given to the synthesis methods and their effects on the textural, structural and surface chemistry properties of activated carbons. Then, the application for the removal of NO2 and the related interaction mechanisms are discussed through a focus on the role of their porous texture and surface chemistry. From the available published data, the relation between the activated carbons performance and their physico-chemical properties has been presented. Furthermore, a mechanism including physisorption, reduction and chemisorption of NO2 on activated carbons has been proposed.
Aerosol-Assisted Synthesis of Submicron Particles at Room Temperature Using Ultra-Fine Liquid Atomization Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-10 Maksim Mezhericher, Janine K. Nunes, Jan J. Guzowski, Howard A. Stone
Aerosol-assisted particle technologies are common in commercial atomizing devices for producing micron-sized droplets, which upon evaporation of solvent typically yield particles in the micron to submicron range obtained from a process of droplet-to-particle conversion. In this paper, we demonstrate a technology that allows room-temperature manufacturing of particles O(100-500) nm in diameter by generating and drying of submicron droplet aerosols. As measured for water atomization, the produced droplets of O(200) nm in mean diameter are an order of magnitude smaller than 3-5 µm water droplets usually obtained from commercial atomizers and nebulizers. This reduction in droplet size promotes evaporation of solvent around two orders of magnitude faster than for the droplets produced by conventional atomization devices. Such rapid solvent evaporation enables formation of submicron particles even in the limit of room temperature drying conditions in a compact laboratory-scale setup, as we demonstrate in this study for sodium chloride and silica and titania xerogel particles. Ultra-fine diameters of the generated droplets enable the usage of more concentrated precursor solutions, e.g. ten or even one hundred times, to obtain the same final particle size as conventional aerosol-assisted setups. Based on the experimental study, we establish mathematical expressions correlating the mean particle size and production capacity with solute concentration in the precursor, physical properties of the solution and the atomizing air pressure. Finally, we compare and demonstrate the advantages of the developed system over the existing aerosol-assisted processes in terms of smaller particle size, larger overall and specific production capacities, and higher estimated energy efficiency. The results suggest that this economical and scalable method can be utilized for aerosol-assisted submicron particle synthesis in different applications.
Flowing water enabled piezoelectric potential of flexible composite film for enhanced photocatalytic performance Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-09 Baoying Dai, Hengming Huang, Fulei Wang, Chunhua Lu, Jiahui Kou, Lianzhou Wang, Zhongzi Xu
Fast charge transfer and low recombination rate are two vital requirements to achieve high photocatalytic activity. In this work, we report the conversion of flowing water energy to piezoelectric potential on a new type of flexible composite film PVDF-Na0.5Bi0.5TiO3-BiOCl0.5Br0.5 (PV-N-B) containing PVDF-Na0.5Bi0.5TiO3 (PV-N) substrate and BiOCl0.5Br0.5, which significantly boosts the charge transfer of the photocatalytic composite film, resulting in improved photocatalytic capability by 2.33 times. The role of piezoelectric potential in photocatalysis process has been discussed in detail and the results reveal that higher potential output is more beneficial for photocatalytic performance enhancement. Moreover, the photocatalytic degradation intermediates of tetracycline (TC) over PV-N-B were detected by liquid chromatography-mass spectrometer and the possible photodegradation pathway of TC has been reasonably proposed. It is verified that superoxide radicals are the main active species for PV-N-B to degrade TC. The durability experiments demonstrate the good stability of flexible composite film PV-N-B. In a wider perspective, this work provides an efficient flexible composite film, with great capability in converting flowing water energy into piezoelectric potential and improving photocatalytic activity, to bring the environmental pollution under control.
Hierarchically Porous Carbon Derived from Metal-Organic Frameworks for Separation of Aromatic Pollutants Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-09 Wei Teng, Nan Bai, Zehan Chen, Junming Shi, Jianwei Fan, Wei-xian Zhang
Adsorption and Desorption of U(VI) on Different-size Graphene Oxide Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-09 Xia Liu, Ju Sun, Xuetao Xu, Ahmed Alsaedi, Tasawar Hayat, Jiaxing Li
Dissolution and reaction in a CO2-brine-clay mineral particle system under geological CO2 sequestration from subcritical to supercritical conditions Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-09 Pil Rip Jeon, Doo-Wook Kim, Chang-Ha Lee
To support effective geological CO2 sequestration design and operation, dissolution and reaction in CO2-brine-clay mineral particle systems (sepiolite and montmorillonite) were studied under subcritical to supercritical CO2 conditions (10 bar to 150 bar at 45 °C and 65 °C). The order of ion dissolution from the framework of sepiolite in the brine was slightly different under each experimental condition, whereas the order of dissolved ion concentration from the montmorillonite was not varied. The solubility of CO2 was lower in the CO2-brine-clay mineral particle system than in a CO2-brine system. Precipitation of amorphous silica as a secondary mineral formation was observed after the reaction of both sepiolite and montmorillonite. The CO2 solubility model, considering ion concentration and aqueous silica, reasonably predicted the CO2 solubility from subcritical to supercritical conditions. The kinetic rate constant of the dissolution reaction of sepiolite was correlated with the initial pH of the brine. After reaction with high-pressure CO2-saturated brine, the micro-crystallinity of sepiolite did not change, whereas the basal (001) plane of montmorillonite showed deformation in micro-crystallinity after the dissolution reaction. By contrast, reaction with the CO2–saturated brine led to a decrease in the surface area of sepiolite and an increase in the surface area of montmorillonite.
Superior Electrochemical Properties of Micron-Sized Aggregates of (Co0.5Fe0.5)3O4 Hollow Nanospheres and Graphitic Carbon Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Young Jun Hong, Seung-Keun Park, Kwang Chul Roh, Jung-Kul Lee, Yun Chan Kang
Morphology-controlled micron-sized aggregates consisted of hollow nanospheres and graphitic carbon are considered to be efficient electrode materials for lithium-ion batteries because the advantages of hollow nanospheres are combined with those of micron-size powders with easy processability. In this study, carbon microspheres with extremely large surface area of 3350 m2 g-1 are successfully used as templates to synthesize (Co0.5Fe0.5)3O4-graphitic carbon (CoFeO-GC) composite microspheres, which in turn, are composed of hollow nanospheres. The CoFe alloy nanospheres act as catalyst in formation of graphitic carbon during reduction process and transform into metal oxide hollow nanospheres after oxidation by nanoscale Kirkendall diffusion. Owing to their unique structure, CoFeO-GC composite microspheres show lithium-ion storage performances superior to those of the CoFeO-amorphous carbon composites with ultrafine nanocrystals and dense structure. The CoFeO-GC composite microspheres have extremely high capacities of 1072 and 681 mA h g-1 at current densities of 1 and 3 A g-1, respectively, after 350 cycles. This hybrid structure employs synergistic effect of the hollow nanosphere aggregate and high content of graphitic carbon with high electrical conductivity, resulting in superior cycling and rate performances, when tested as anode materials for lithium-ion batteries.
Chemically and thermally stable isocyanate microcapsules having good self-healing and self-lubricating performances Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Dawei Sun, Yong Bing Chong, Ke Chen, Jinglei Yang
Sorption and Desorption of Anionic, Cationic and Zwitterionic Polyfluoroalkyl Substances by Soil Organic Matter and Pyrogenic Carbonaceous Materials Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Yue Zhi, Jinxia Liu
The fraction of pyrogenic carbonaceous materials (PCMs) left in aqueous film-forming foams (AFFFs) source zones may strongly affect the persistence of perfluoroalkyl and polyfluoroalkyl substances (PFASs). To examine the hypothesis and gain an additional perspective on the potential contributions of different organic phases present in soil, we measured sorption and desorption of five AFFF relevant PFASs, one cationic (perfluoroctaneamido ammonium iodide, PFOAAmS), two anionic (perfluorooctane sulfonate, PFOS; perfluorooctanoic carboxylate, PFOA), and two zwitterionic (perfluorooctane amido betaine, PFOAB; 6:2 fluorotelomer sulfonamido betaine, 6:2 FTAB), by three types of PCMs (biochar, soot, and oil-free soot) and soil organic matter (SOM, presented by Pahokee peat) by single-solute batch sorption experiments. It was found that sorption to PCMs is substantially stronger and nonlinear than SOM, especially for the cationic PFOAAmS. Strong sorption to PCMs discovered in this study suggests that such phenomenon can lead to high retardation of PFASs in the AFFF source zone and decreased mobility of PFASs in groundwater, especially for the precursor compounds to the legacy perfluoroalkyl acids. Fouling of PCMs by unburnt oil would hinder the surface activity of PCMs and consequently lower the sorption of PFAS, thereby facilitating PFAS mobility. Moreover, sorption hysteresis was observed in all the systems with sorption of 6:2 FTAB by biochar being the most significant. This study for the first time provided the evidence that PCMs are potentially a significant sink of PFASs in AFFF-impacted sites.
Production of glycerol carbonate using a novel Ti-SBA-15 catalyst Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Parmila Devi, Umashankar Das, Ajay.K. Dalai
The present study was focused on the development of a green process for the production of glycerol carbonate (GYC) from glycerol and dimethyl carbonate using a Ti-SBA-15 catalyst. Ti-SBA-15 catalysts with varying Si/Ti ratio were synthesized in-situ using sol gel method and characterized using various chemical and spectroscopic techniques to study the effects of Ti incorporation on surface and catalytic properties of Ti-SBA-15 catalysts. The process parameters were optimized to obtain high glycerol conversion and GYC selectivity. Ti-SBA-15 catalysts with lower Si/Ti ratio demonstrated higher glycerol conversion and GYC selectivity as compared to the catalysts with higher Si/Ti ratio. A regression model was developed to analyze the correlation between reaction parameters and reaction outcomes which suggest that the reaction temperature has the most significant effect on the glycerol conversion and GYC selectivity. A reaction mechanism portraying the role of Ti-SBA-15 in facilitating the formation of GYC was presented. GYC was formed via the formation of O-methoxy carbonyl intermediate and the reaction was catalyzed by the Lewis acidic nature of Ti-SBA-15 catalyst. A kinetic model was proposed based on the results obtained from this study. In addition, reusability study of the production GYC from glycerol using Ti-SBA-15 suggests that the process has the commercialization potential.
Aminolysis of cyclic-carbonate vegetable oils as a non-isocyanate route for the synthesis of polyurethane: a kinetic and thermal study Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Wander Y. Pérez-Sena, Xiaoshuang Cai, Nasreddine Kebir, Lamiae Vernières-Hassimi, Christophe Serra, Tapio Salmi, Sébastien Leveneur
Production of polyurethane is increasing since the recent years. Nevertheless, this production uses hazardous chemicals, which is isocyanate. Academy has put a lot of effort to develop some non-isocyante polyurethane routes. One of the most promising is the aminolysis of cyclic-carbonate by diamine. To industrialize this way of production, kinetic and thermodynamic data are needed. The first steps were to optimize the production of methyl oleate, epoxidized methyl oleate and carbonated methyl oleate. Then, a kinetic model was built for a model reaction which is the aminolysis of carbonated methyl oleate by n-butylamine by taking into account the side reaction of amidation. The model fits correctly the experimental data. A Tian-Calvet calorimeter was used to determine the different reaction enthalpies. It was found that the reactions of aminolysis and amidation were few exothermic.
Insights into the Sm/Zr co-doping effects on N2 selectivity and SO2 resistance of a MnOx-TiO2 catalyst for the NH3-SCR reaction Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Chuanzhi Sun, Hao Liu, Wei Chen, Dezhan Chen, Shuohan Yu, Annai Liu, Lin Dong, Shuai Feng
A series of Sm- and/or Zr-doped MnOx-TiO2 catalysts were prepared, and the catalysts exhibited better N2 selectivity and SO2 resistance than the undoped MnOx-TiO2 catalyst for the selective catalytic reduction of NO by NH3 (NH3-SCR). The reasons for the good N2 selectivity and SO2 resistance of the catalysts were proposed. X-ray photoelectron spectroscopy (XPS) combined with density functional theory (DFT) calculations suggested that electron transfer between the manganese and samarium species by Mn4++Sm2+↔Mn3++Sm3+ redox cycles occurred in the Sm-containing catalysts. Furthermore, electron transfer from Sm2+ to Mn4+ suppressed electron transfer from NH3 to Mn4+, inhibiting the formation of NH2 or NH. Thus, the pathway for NH generation was removed, and the reaction of 2NH+4NO→3N2O+H2O was prevented. Consequently, the N2 selectivity of the NH3-SCR reaction was enhanced. In situ diffused reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) combined with thermogravimetry, differential scanning calorimetry and mass spectrometry (TG-DSC-MS) results revealed that the deposition rate of sulfate species decreases after Sm doping, which was also attributed to the suppressed electron transfer from SO2 to Mn4+, i.e., the oxidation of SO2 to SO3. Thus, the catalysts exhibited better SO2 resistance.
Constructing conductive conduit with conductive fibrous infilling for peripheral nerve regeneration Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Wei Jing, Qiang Ao, Lin Wang, Zirong Huang, Qing Cai, Guoqiang Chen, Xiaoping Yang, Weihong Zhong
Nerve conduits are essential for guiding the regeneration of injured peripheral nerves, and empty conduits usually cannot perform satisfactorily due to problems with cell migration and nutrient transportation. Taking the electrophysiological features of nervous tissues into consideration, in this study, a conductive conduit filled with parallel-aligned conductive fibers was constructed, and its potential for enhancing peripheral nerve regeneration was evaluated in vivo. The conductive fibers were prepared via depositing a polypyrrole (PPY) shell onto electrospun parallel-aligned poly(lactide-co-glycolide) (PLGA) fibers. The conductive conduit was prepared from PLGA/PPY emulsion via dip-coating on a mandrel. Both materials were non-cytotoxic to PC12 cells and were able to promote cell proliferation and differentiation. Moreover, the aligned fibers provided strong orientation guidance for nerve fibers. Sciatic nerve defects were created in Sprague-Dawley rats, and empty or fiber-filled conduits were sutured into the defects. Meanwhile, the control groups received PLGA conduits or autografts. Twelve weeks post-operation, the fiber-filled conductive conduit showed much better nerve regeneration outcomes than both the PLGA conduit and the empty conductive conduit and showed comparable results to the autograft in terms of electrophysiological properties, sciatic function indices, and regenerated myelinated nerve fibers as well as axon diameter and myelin thickness. It is possible that the oriented conductive fibers in the conductive conduit provide a favorable micro-environment for nerve growth due to their capacity to transmit self-originated electrical stimulation between cells. The results of animal testing confirmed the feasibility of using combined conductive conduits for guiding nerve regeneration.
Carbon and hydrogen isotope fractionation of phthalate esters during degradation by sulfate and hydroxyl radicals Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Dan Zhang, Langping Wu, Jun Yao, Hartmut Herrmann, Hans-Hermann Richnow
Oxygen-incorporation in Co2P as a non-noble metal cocatalyst to enhance photocatalysis for reducing water to H2 under visible light Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Yuguang Chao, Jianfeng Zheng, Haixia Zhang, Feng Li, Feng Yan, Yisheng Tan, Zhenping Zhu
Precious metal-free hybrid photocatalysts with low cost and high efficiency of photocatalytic H2 evolution are of great significance for clean energy. Herein, we report that oxygen-incorporation in Co2P, a noble metal-free co-catalyst used for forming a hetero-structure photocatalyst CdS/o-Co2P, greatly improves the efficiency and durability for photocatalytic hydrogen production from water. Regulating the kinetics of water reduction by different oxygen incorporation levels (determined by phosphorization time) was investigated to optimize the activity of photocatalytic H2 evolution. The intimate interaction between the CdS nanorods and cocatalyst o-Co2P enhances the separation of the photo-generated electron–hole pairs. Consequently, the optimal loading content of o-Co2P is 5 wt% for CdS, phosphorization time is 80 min, giving a photocatalytic H2 production rate of 184.48 mmol g−1 h−1, and the apparent quantum yield at 420 nm over CdS/o-Co2P-5wt% reaches 22.17%. This study provides a simple method for constructing low cost and high performance photocatalysts, which enhance photocatalytic H2 evolution.
Effect of Surface Fluorination of P25-TiO2 on Adsorption of Indoor Environment Volatile Organic Compounds Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Zahra Shayegan, Fariborz Haghighat, Chang-Seo Lee, Ali Bahloul, Melanie Huard
The application of photocatalytic oxidation (PCO) in VOCs degradation is greatly hindered at high humidity levels. This is because VOCs compete with water molecules to adsorb on the generally hydrophilic photocatalyst surface, where photocatalytic reactions take place. Modified P25-TiO2 nanoparticles with surface fluorination (F-P25) was prepared to reduce the surface hydrophilicity of Degussa P25. The prepared samples were characterized by BET, SEM, and XPS tests. Herein, the effects of surface fluorination on the adsorption capacity of P25-TiO2 nanoparticles towards toluene, methyl ethyl ketone (MEK), and isobutanol, representing different classes of indoor air pollutants, were investigated. After surface fluorination, the adsorption capacity of modified TiO2 was compared to bare-TiO2 in a continuous reactor at four different relative humidity levels (i.e., 0, 20, 40, and 60%). Three adsorption isotherms, including Langmuir, Freundlich, and BET, were used to model the adsorption experimental data. The equilibrium data for the adsorption of all compounds showed the best fit with the BET model, and the Freundlich model also represented a good fit. Moreover, the results indicated that the surface fluorination of P25 increased adsorption capacity about two times for toluene in three humid conditions (0, 20, and 40%) compared to bare-P25. By combining the benefits of using an easy modification method by a low-cost modifier and using P25-TiO2, which is the most common commercialized photocatalyst, an effective method has been developed to enhance the efficiency of VOCs removal in indoor air environments.
Electrodriven transport of chromium (VI) using 1-octanol/PVC in polymer inclusion membrane under low voltage Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Xiaorong Meng, Conghui Wang, Tingting Ren, Lei Wang, Xudong Wang
The transport behaviour of Cr(VI) from the aqueous phase through a polymer inclusion membrane (PO-PIM) containing 1-octanol (OCT) as carrier and polyvinyl chloride (PVC) as support at a low voltage drive (0–30 V) is investigated. The correlation between the OCT content and the surface or cross-sectional micromorphology of PO-PIM is also analysed. Under optimised mass transfer conditions, the transmission rules and mechanism of Cr(VI) under an electrodriven membrane extraction system are investigated. Results show that the surface and interior of PO-PIM exhibit micro/nanopores with an OCT content exceeding 50% (w/w). The mass transfer behaviour of OCT to Cr(VI) conforms to the proton coupling mechanism. The voltage drive effectively solves the residue problem of Cr(VI) in the membrane phase, and the permeability coefficient (P) of PO-PIM to Cr(VI) increases with the voltage. The P of PO-PIM to Cr(VI) reaches 43.38 μm·s−1 at 30 V when the OCT content is 82.8% and the feed and stripping phases are pH 2.0 HCl solution and 0.1 mol·L−1 NaOH solution environments, respectively. After the introduction of hydrophobic kerosene into the membrane phase, the stability of the membrane is significantly enhanced. When the composition ratio of kerosene/OCT/PVC is 0.8:2.2:0.5 and the voltage is 30 V, the initial current density rise is only 0.1 A and the pH increases slightly with the repeated use of PO-PIM to four cycles.
Apparent kinetics of the water-gas-shift reaction in biomass gasification using ash-layered olivine as catalyst Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Joanna Kryca, Juraj Priscak, Joanna Łojewska, Matthias Kuba, Hermann Hofbauer
Substitution of fossil fuels for production of electricity, heat, fuels for transportation and chemicals can be realized using biomass steam gasification in a dual fluidized bed (DFB). Interaction between biomass ash and bed material in a fluidized bed leads to transformation of the bed particle due to enrichment of components from the biomass ash resulting in the development of ash layers on the bed particle surface. These ash-rich particle layers enhance the catalytic activity of the bed material regarding the water-gas-shift reaction and the reduction of tars. The water-gas-shift reaction at conditions typical for dual fluidized bed biomass gasification at a temperature of 870 °C was investigated. Diffusion and heat transfer limitations were minimized using a lab-scale experimental set-up consisting of a gas mixing section and a quartz glass reactor in which the catalyst is investigated. The following new rate expression for the water-gas-shift reaction in dual fluidized bed gasification of biomass was empirically developed, which takes ash layer formation into account: r Olivine _ ash - layer = 8 , 9 · 10 - 6 exp ( - 95000 RT ) p CO 1 , 96 p H 2 O 1 , 81 p CO 2 - 0 , 75 p H 2 - 1 , 69
Synthesis of PVA-g-POEM graft copolymers and their use in highly permeable thin film composite membranes Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Do Hyun Kim, Min Su Park, Yeji Choi, Ki Bong Lee, Jong Hak Kim
Polymeric gas separation membranes are a viable solution to mitigate greenhouse gas emissions directly linked to global warming due to their environment-friendly synthetic process and low cost. Poly(vinyl alcohol) (PVA) synthesized via non-petroleum routes is an eco-friendly material with several advantages for membrane applications such as good film-forming properties, good compatibility, and water solubility. Despite these benefits, the gas barrier property of PVA prevents its application in gas separation membranes. Therefore, we synthesized a graft copolymer consisting of PVA main chains and poly(oxyethylene methacrylate) (POEM) side chains via one-pot free radical polymerization and applied it to a highly CO2 permeable thin film composite membrane. Synthesis of the PVA-g-POEM graft copolymer was confirmed by Fourier transform infrared and proton nuclear magnetic resonance spectroscopy. X-ray diffraction and differential scanning calorimetry analyses revealed that the crystallinity of PVA-g-POEM decreased gradually with increasing POEM content, with the PVA-g-POEM graft copolymer becoming amorphous at a POEM content of 64 wt%. The composite membrane prepared with PVA-g-POEM exhibited a high CO2 permeance (347.3 GPU) and moderate selectivity (21.6 for CO2/N2). This performance is superior to other PVA-based membranes reported to date and is close to the target area for commercialization. The improved separation performance is due to the intermingled CO2-philic POEM side chains and the decrease in crystallinity of PVA.
Microspherical MnO2-CeO2-Al2O3 mixed oxide for monolithic honeycomb catalyst and application in selective catalytic reduction of NOx with NH3 at 50-150 °C Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Chao Wang, Feng Yu, Mingyuan Zhu, Xugen Wang, Jianming Dan, Jinli Zhang, Peng Cao, Bin Dai
MnOx-CeO2-Al2O3 microspheres (MSs) were successfully designed and synthesized via spray drying (SD) and easily used for monolithic honeycomb catalyst (MHC). The as-obtained MnOx-CeO2-Al2O3 (SD) catalyst exhibited a great BET surface area of 201.4 m2/g, a pore volume of 0.29 cm3/g, and an average pore diameter of 5.8 nm. Furthermore, the MnOx-CeO2-Al2O3 (SD) MSs delivered much more Olatt sits resulting in enhanced catalytic activity at low temperature. The MnOx-CeO2-Al2O3 (SD) performed excellent NOx conversion of 97.4% and N2 selectivity of 94.5% at 150 °C with a gas hourly space velocity (GHSV) of 15000 h-1, and NOx concentration of 500 ppm. Even at 50 °C and 100 °C, the titled product still exhibited great N2 selectivity of 95.5% and 96.1%, respectively, corresponding to the NOx conversion of 55% and 98.0%, respectively. The MnOx-CeO2-Al2O3 (SD) monolithic honeycomb catalyst (MHC) was prepared by vacuum-impregnation method. The MnOx-CeO2-Al2O3 (SD-MHC) delivered NOx conversion of 93% at 150 °C with a GHSV of 2000 h-1, and NOx concentration of 500 ppm. Even at 50 °C and 100 °C, the titled product still performed NOx conversion of 55% and 83%, respectively. The MnOx-CeO2-Al2O3 (MHC) performed great catalytic activity in the low temperature arrange from 50 to 150 °C and presented potential application in stationary industrial installations.
Preparation of a novel nanobiocatalyst by immobilizing penicillin acylase onto magnetic nanocrystalline cellulose and its use for efficient synthesis of cefaclor Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Zi-Xuan Huang, Shi-Lin Cao, Pei Xu, Hong Wu, Min-Hua Zong, Wen-Yong Lou
Magnetic nanocrystalline cellulose (MNCC) was prepared and used as an enzyme support for the immobilization of penicillin acylase (PA). A novel coupling agent, tri(hydroxymethyl)phosphine(THP) instead of the conventional glutaraldehyde(GA), was used as a crosslinker in this study. The obtained results showed that the immobilized PA with THP (PA-THP-MNCC) had high enzyme loading (172.3 mg/g) and activity recovery (77.6%) in the optimal preparation conditions, which were remarkably superior to those of the counterpart using GA (PA-GA-MNCC, 148.4 mg/g and 48.7%, respectively). Compared with free PA and PA-GA-MNCC, PA-THP-MNCC displayed a higher optimum pH and temperature, and manifested relatively higher enzyme-substrate affinity and catalytic efficiency. In addition, PA-THP-MNCC exhibited significantly enhanced stability. Furthermore, PA-THP-MNCC was successfully employed for synthesis of cefaclor, an important second-generation cephalosporin antibiotic, affording a significantly higher yield of 84% than that reported previously.
Effective biodiesel synthesis from waste cooking oil and biomass residue solid green catalyst Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Nasar Mansir, Siow Hwa Teo, Idris Rabiu, Yun Hin Taufiq-Yap
Biodiesel has recently received greater concern as one of the reliable and sustainable source of energy. Production of biodiesel is hampered by both feedstock availability and catalyst system. This work successfully utilized the waste egg shell to develop a bimetallic mixed oxide catalyst, and waste cooking oil characterised by high free fatty acid (FFA) as feedstock, towards methyl ester production under mild reaction condition in one-step transesterification process. The properties of the catalyst were assessed using XRD, BET, SEM, EDX and TPD-CO2. The prepared catalyst was successfully recorded a high biodiesel yield of 92.1% under the optimized reaction conditions of 15:1 methanol to oil molar ratio, 3 wt% catalyst loading, 80 °C reaction temperature and 3 h reaction time. The recovered catalyst was reused in five cycles without significant loss in activity. The leaching of catalytic Ca2+ active site was reduced when transition bimetallic mixed oxides were added to the CaO surface.
Structure Regulation of ZnS@g-C3N4/TiO2 Nanospheres for Efficient Photocatalytic H2 Production under Visible-Light Irradiation Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Chao Zhang, Yuming Zhou, Jiehua Bao, Jiasheng Fang, Shuo Zhao, Yiwei Zhang, Xiaoli Sheng, Wenxia Chen
High-quality mesoporous or hollow ZnS@g-C3N4/TiO2 nanospheres were fabricated successfully via structure regulation strategy for efficient photocatalytic H2 production under visible-light irradiation. The entire process was started with the construction of solid ZnS@g-C3N4/TiO2 (S-ZnS@g-C3N4/TiO2) nanospheres. Then, via TiO2 nanosheets (NSs) in situ growth or Ostwald ripening treatment, S-ZnS@g-C3N4/TiO2 could be converted into mesoporous or hollow ZnS@g-C3N4/TiO2 nanospheres automatically. The obtained porous ZnS@g-C3N4/TiO2 nanospheres were featured of regular shape, high porosity, large specific surface area and adjustable g-C3N4 content. In mesoporous ZnS@g-C3N4/TiO2 (M-ZnS-g-C3N4/TiO2) nanospheres, the specially constructed mesoporous served as channels for the access of reactants in heterogeneous catalysis. Besides, the electron-sink function of ZnS NPs and C–SOx–C sulfone bridges between ZnS and g-C3N4 could improve visible-light H2 production of M-ZnS-g-C3N4/TiO2 significantly. Additionally, the prepared hollow ZnS@g-C3N4/TiO2 (H-ZnS@g-C3N4/TiO2) nanospheres showed a lower photocatalytic H2 production than M-ZnS-g-C3N4/TiO2 due to the decreased specific surface area. Compared with traditional g-C3N4 wrapping method, the proposed structure regulation strategy is simple, effective and structural controllable. Finally, a possible photocatalytic mechanism for visible-light H2 production by porous ZnS@g-C3N4/TiO2 nanospheres was tentatively proposed.
Multi-walled Carbon Nanotubes Supported Nickel Nanoparticles Doped with Magnesia and Copper for Adiponitrile Hydrogenation with High Activity and Chemoselectivity under Mild Conditions Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Yang Lv, Jun Li, Sheng Feng, Pingle Liu, Fang Hao, Wei Xiong, He'an Luo
Multi-walled carbon nanotubes supported nickel nanoparticles doped with magnesia and copper catalysts were prepared by incipient wetness impregnation method and used in adiponitrile (ADN) hydrogenation to 6-aminohexanenitrile (ACN) and 1,6-hexanediamine (HMDA). The prepared catalysts were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), temperature-programmed hydrogen reduction (H2-TPR), H2 chemisorption, temperature-programmed ammonia desorption (NH3-TPD), temperature-programmed carbon dioxide desorption (CO2-TPD) and N2 adsorption-desorption. The results showed that the introduction of magnesia could lead to form NiO-MgO eutectic so as to restrain the reduction of nickel oxide, and it might increase the alkaline site which is conducive to the formation of primary amines in ADN hydrogenation so as to increase the selectivity to ACN and HMDA. Moreover, the formation of NiO-MgO eutectic can also inhibit the sintering of nickel in a certain extent, hence promote the nickel dispersion. And it was revealed that doping of copper can highly promote the catalytic activity by attributing to the strong synergetic effect between copper and nickel which can lead to better dispersion of nickel nanoparticles, larger metallic surface area, lower reduction activation energy of nickel oxide precursor and higher ratio of Ni0+ on the surface of the support. Multi-walled carbon nanotubes supported nickel nanoparticles doped with copper and magnesia presents the best catalytic performance of 96.27% conversion of ADN and 91.22% selectivity to ACN and HMDA under 2 MPa and lower temperature of 328 K.
Interaction of phosphorus with a FeTiOx catalyst for selective catalytic reduction of NOx with NH3: Influence on surface acidity and SCR mechanism Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Xiansheng Li, Kezhi Li, Yue Peng, Xiang Li, Yani Zhang, Dong Wang, Jianjun Chen, Junhua Li
Phosphorus were employed to investigate the influences on the acid sites and reaction mechanism of FeTiOx SCR catalyst. The introduction of phosphorus inhibited the SCR activity by suppressing the redox property, decreasing the surface acidity and reducing the surface area. In particular, phosphorus preferentially bonded to the electron-deficient Ti4+ and Fe3+ cations on the surface as P-O-Fe and P-O-Ti, thereby blocking the Lewis acid sites (Fe-NH3 or Ti-NH3). Although phosphate provided additional Brønsted acid sites (P-O-NH4+), the larger decrease of Lewis acid sites results in the decrease of total surface acidity. The newly formed Brønsted acid sites showed less SCR active at low temperature and exhibited high thermal stability and reactivity at high temperature, which leads to a new pathway following the L-H mechanism and an enhancement of high temperature performance.
Evaluation of the potential of dimethyl phthalate degradation in aqueous using sodium percarbonate activated by discharge plasma Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-07 Tiecheng Wang, Hanzhong Jia, Xuetao Guo, Tianjiao Xia, Guangzhou Qu, Qiuhong Sun, Xianqiang Yin
Phthalates, as additives in the plastic production process, were able to enter the water environment, causing huge risks to ecological environment and human health. The potential of phthalates elimination in aqueous using sodium percarbonate (SPC) activated by discharge plasma (marked as “SPC + plasma”) was evaluated, with dimethyl phthalate (DMP) as a model pollutant. Experimental results showed that about 92.1% of DMP was eliminated in the “SPC + plasma” system with the treatment time of 30 min, which was 30.7% higher than that in sole plasma system, and the synergetic intensity for DMP elimination reached up to 127.0; and the energy yield was also raised by 131%. H2O2 and ·OH radicals formation were promoted but ozone concentration decreased in the “SPC + plasma” system. Appropriate SPC dosage benefited DMP elimination, and the synergetic intensity increased from 2.0 to 127.0 as the SPC dosage increased from 0.06 mmol L-1 to 0.12 mmol L-1. ·OH radicals, O2·-, 1O2, and CO3·- played crucial roles in DMP elimination, and the roles of O2·- and 1O2 were strengthened in the “SPC + plasma” system. Ultraviolet-visible spectroscopy measurement, total content of organic carbon, atomic force microscopy and three-dimensional fluorescence analysis demonstrated that DMP molecular structure was destroyed during treatment, and some smaller molecular fractions were generated. The main intermediates included phthalic acid monomethyl ester, phthalic acid, o-phthalic anhydride, acetic acid, formic acid, and oxalic acid. The possible enhancement mechanisms for DMP elimination in the “SPC + plasma” system were proposed.
Numerical investigation of a coarse-grain discrete element method in solid mixing in a spouted bed Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-06 Kazuya Takabatake, Yuki Mori, Johannes Khinast, Mikio Sakai
We describe the effectiveness of the coarse-grain model of the discrete element method (DEM) in solid mixing in a spouted bed. The coarse-grain model was developed originally to simulate large-scale DEM simulations efficiently, where the coarse-grain particle represents a group of original particles. In previous studies, the adequacy of the coarse-grain model was proven in a pneumatic conveying system and bubbling fluidized beds through verification and validation tests. In this study, the coarse-grain model has been applied to solid mixing in a spouted bed. Agreement of the mixing state is shown between an original particle system and coarse grain model systems. Subsequently, correlation between solid mixing and macroscopic behavior of the solid particles is examined in the present study. The macroscopic properties such as solid-particle spatial distribution, pressure drop and velocity distribution of the solid phase are confirmed to correspond quantitatively in the coarse-grain model and an original particle system. Finally, the calculation efficiency of the coarse-grain model is evaluated. Consequently, the coarse-grain model is shown to be able to efficiently investigate the solid mixing in a spouted bed.
Transition Metal Catalyzed Sulfite Auto-oxidation Systems for Oxidative Decontamination in Waters: A state-of-the-art minireview Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-06 Danna Zhou, Long Chen, Jinjun Li, Feng Wu
Sulfate radical (SO4•–) is believed to be one of the most highly reactive oxidants, as superior as hydroxyl radical (HO•), for various organic/inorganic contaminants removal in the field of pollution control chemistry. In the recent decade, sulfate radical-based advanced oxidation processes (SR-AOPs) have been developed quickly primarily due to the selective oxidation and high oxidative potential and therefore hold great promises. Although peroxydisulfate (PDS) and peroxymonosulfate (PMS) have been extensively utilized in various SR-AOPs, new attempts have been made to replace PDS/PMS with sulfite for the purpose of SO4•– generation at lower cost. Indeed, some significant progresses have been achieved in driving SO4•– generation from transient metal catalyzed sulfite auto-oxidation systems to oxidize contaminants. The background, basic mechanisms, and application of the transition metal catalyzed sulfite auto-oxidation systems in contaminants detoxification and microorganism inactivation are reviewed in this work. Meanwhile, we hereby also want to point out several important unresolved issues for future investigation. (1) How to realize quick reactions at near neutral pH? (2) How to achieve high rate of mineralization as equally as or at least close to the apparent complete elimination of substrates? (3) What are the relative contributions of various oxysulfur radicals to the transformation of contaminants. (4) Is it possible to control the extent of substrates oxidation so as to get target transformed products with desired properties? If so, SR-AOPs can be upgraded as product-oriented AOPs (PO-AOPs). This state-of-art minireview aims to discuss abovementioned issues and presents some recent progresses in this field.
Modifier-free fabrication of durable and multifunctional superhydrophobic paper with thermostability and anti-microbial property Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-06 Gang Wen, Xiaoyu Gao, Pan Tian, Lieshuang Zhong, Zelinlan Wang, Zhiguang Guo
The superhydrophobic paper containing CMC, HAP and ZnO was prepared by a novel and facile method with eco-environmental and modifier-free process. The superhydrophobic property is effectively controlled by different amount of ZnO, which might be effect of surface roughness of the paper. Except for the common performances, such as self-cleaning property, chemical durability and mechanical abrasion durability, the excellent thermal stability and anti-bacterial properties will dramatically extend the practical applications of the paper. In addition, such paper still maintains its superhydrophobicity after flammable oil adsorption-combustion, further validating its excellent fire-resistant property. The combination of superhydrophobicity and flame retardancy can largely enhance the durability of the paper. These characteristics make the multifunctional paper a better candidate than the commercial paper, which may be a breakthrough in paper-making industries.
A magnetic pH-induced textile fabric with switchable wettability for intelligent oil/water separation Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-06 Tao Yan, Xiaoqing Chen, Taiheng Zhang, Jingang Yu, Xinyu Jiang, Wenjihao Hu, Feipeng Jiao
Wastewater discharged in human daily life, and oil spill accidents occurred frequently. The novel interface materials used for controllable oil/water separation have gained more and more attention. In this work, a facile, environmentally friendly approach is presented to fabricate a magnetic textile fabric with pH-controllable wettability between superhydrophobicty and superhydrophilicity. We prepared this magnetic textile fabric by immersing in lauric acid (LA)-TiO2 composites and Fe3O4 nanoparticles. The resulted pH-conrtollable textile fabric possessed selective separation performance for oil/water mixtures with efficiency higher than 99% and high flux for oil (11000 L h-1 m-2). Moreover, the magnetic material is recyclable, the detailed experiments were conducted in this work for 25 cycles of oil/water mixture separation remaining unchangeable separation efficiency (>98%). For neutral water (e.g., at pH 7), the novel Fe3O4/LA-TiO2 textile fabric demonstrated superhydrophobicity/ superoleophilicity in air. For alkaline water (e.g., at pH 12), the textile fabric showed superhydrophilicity and underwater superoleophobicity. The Fe3O4/LA-TiO2 textile fabric could separate a series of light or heavy oil/water mixtures with high separation efficiency up to 99.1%, high oil flux of 7400–11000 L h-1 m-2 and water flux of 5300–5700 L h-1 m-2. In addition, thermal stability (∼180 0C) and long exposure to ultraviolet rays showed that the textile fabric was stable in harsh environment. The textile fabric can be easily removed through a magnet due to its magnetic properties. It can be concluded from the results that Fe3O4/LA-TiO2 textile fabric is a good candidate for practical applications, such as water restoration and oil-spill treatment.
UiO-66 derived etched carbon/polymer membranes: High-performance supports for the extraction of organic pollutants from water Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-06 Carlos Palomino Cabello, Maria Francesca Font Picó, Fernando Maya, Mateo del Rio, Gemma Turnes Palomino
Herein we report the use of the zirconium metal-organic framework (UiO-66) as precursor to prepare porous carbons by a direct carbonization step (carbon-ZrO2). By applying a post-carbonization acidic etching treatment with hydrofluoric acid (HF), the initial surface area of the carbon-ZrO2 sample increased from 270 m2 g-1 to 1550 m2 g-1 (carbon-ZrO2-HF). This increase is attributed to the partial removal of the ZrO2 present in the UiO-66-derived carbon. Carbon-ZrO2-HF exhibited fast adsorption kinetics and an outstanding maximum adsorption capacity of 510 mg g-1 for the dye rhodamine B. For practical applications, the obtained porous carbon-ZrO2-HF material was used to fabricate a carbon composite membrane using polyvinylidene fluoride. The prepared membranes were applied as water filtration supports for the extraction of toxic phenols from water, including an endocrine disrupting phenol with widespread exposure: bisphenol A. High efficiency for the simultaneous extraction of phenolic pollutants, and an excellent reusability with a variation of a 2% for 10 consecutive bisphenol A extraction cycles, were obtained. Due to their high and accessible porosity, small particles size, and facile processability into membranes, the UiO-66 derived etched carbons are promising materials for environmental applications, such as the extraction of organic toxic pollutants.
Zn-Al layered double hydroxides as efficient photocatalysts for NOx abatement Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-06 Fredy Rodriguez-Rivas, Adrián Pastor, Cristobalina Barriga, Manuel Cruz-Yusta, Luis Sánchez, Ivana Pavlovic
In this study, we report that layered double hydroxides (LDH) exhibited high photocatalytic activities in degrading NOx gases for the first time. ZnAl-CO3 LDHs with a 1.5 to 3.0 Zn/Al ratio were prepared by a coprecipitation method both with and without hydrothermal treatment. Syntheses were carried out with high and low metal concentrations, the latter being the most favorable in obtaining pure LDHs in the whole Zn/Al ratio range. The samples were characterized by different techniques such as PXRD, FT-IR, ICP mass, TGA, SBET, SEM and Diffuse reflectance (DR). The LDH particles grew as well-defined hexagonal nanolayers, whose size and crystallization depended on the synthetic procedure and the Zn/Al ratio. Those samples with lower crystallinity exhibit the highest specific surface area values (> 50 m2·g-1). The ZnAl-CO3 LDHs were UV light responsive with band–gap values close to 3.5 eV. The LDH photocatalysts show a high performance towards the photochemical oxidation process of NO gas, with efficiencies of around 55%. Remarkably, the ZnAl-CO3 photocatalysts exhibit an impressive selectivity towards the deNOx process, avoiding the emission of the toxic NO2 gas into the atmosphere. Interestingly, these promising deNOx results are repeated when working for a long irradiation period or with the highest concentration of NO in polluted atmospheres.
Green Synthesis of Lignin Nanoparticle in Aqueous Hydrotropic Solution toward Broadening the Window for its Processing and Application Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-06 Liheng Chen, Xiaoyan Zhou, Yunfeng Shi, Bo Gao, Jianping Wu, Thomas B. Kirk, Jiake Xu, Wei Xue
To exploit a green way to produce polymer nanoparticles using biodegradable and renewable macromolecules instead of petroleum-based ones, we initiated a novel and facile method to synthesize lignin nanoparticles (LNPs). The LNPs, having a hydrodynamic diameter ranging from ca. 80 to 230 nm, were formed by self-assembly in a recyclable and non-toxic aqueous sodium p-toluenesulfonate (pTsONa) solution at room temperature, with a lowest concentration of up to 48 g/L. We eliminated the unfavorable factors of restricted processing pH and lignin species by taking advantage of the hydrotropic chemistry and the synergistic dissociation of the entrapped pTsONa and intrinsic phenolic hydroxyl and carboxylic acid moieties of the LNPs. Because of the hydrotropic system, various water-soluble or water-insoluble drugs can be dissolved and encapsulated in the LNPs with an encapsulation efficiency of up to 90%. The drug-encapsulated LNPs also showed great properties, with sustained drug-releasing capability and biocompatibility. Furthermore, the unloaded drugs and free pTsONa could be easily recycled for multiple use, thereby achieving environmental sustainability. This synthesis approach with broad processing window could realize the industrial scale-up production of LNPs and have wide potential applications, including but not limited to versatile drug/bioactive macromolecule loading in the biomedical field.
On The Intra-Fiber Mass Transfer Limitations In Glass-Fiber Catalysts Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-05 Andrey Zagoruiko
The study is dedicated to catalysts on the base glass microfibrous supports. It discusses the issues of the diffusion of reactants in the bulk of glass fibers, using the model reaction of toluene deep oxidation in air at Pt-containing glass-fiber catalyst (GFC). The catalysts with location of Pt particles either at the external fiber surface or in the hypothetical sub-surface layers in the glass bulk are compared. The intra-fiber diffusion of toluene is considered from positions of diffusion in liquid, interpreting glass as super-cooled liquid with high viscosity. The calculations show that at moderate temperatures the diffusion coefficient and corresponding efficiency factor are extremely low due to very high viscosity of high-silica glasses. The apparent reaction rate at sub-surface Pt particles appears to be dramatically lower (by 7-10 orders of magnitude) than that for the surface Pt. It is concluded that even if the sub-surface metal particles really exist, their contribution to the overall performance of GFC is negligible. This result disproves the notion stating that properties of some class of GFCs are defined by sub-surface particles of active component.
Guest-Dependent Pressure Induced Gate-Opening Effect Enables Effective Separation of Propene and Propane in a Flexible MOF Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-05 Xiaoqing Wang, Rajamani Krishna, Libo Li, Bin Wang, Tao He, Yong-Zheng Zhang, Jian-Rong Li, Jinping Li
Propene (C3H6)/propane (C3H8) separation is an important but challenging industrial task. Adsorptive separation using porous materials tends to be an energy- and cost-effective strategy. In this work, a flexible porous MOF named NJU-Bai8 is demonstrated to be a promising adsorbent for the effective separation of C3H6 and C3H8 in a wide temperature range from 298 to 348 K due to its flexible microporous structure, which provides unique guest responsive molecule accommodation. Adsorption isotherms, ideal adsorbed solution theory (IAST) prediction of separation ability, and transient breakthrough on both simulation and experiment were performed to evaluate its separation selectivity and cycling experiments were carried out to explore its structural stability. It was found that the C3H6/C3H8 uptake ratio and IAST selectivity of NJU-Bai8 is 43.2 and 4.6 at 298 K and 20 kPa, respectively. The breakthrough time interval for C3H6 and C3H8 is over 10 min for a C3H6/C3H8/He (20%/20%/60%) mixture under ambient conditions, and this separation ability can maintain more than 10 cycles. Detailed analysis reveals that a guest-dependent pressure induced gate-opening effect in the flexible framework of this MOF is indeed responsible for the observed unique selective adsorption and separation performances. This material also shows good regenerability, being favorable for possible industrial application.
Microwave carbonized cellulose for trace pharmaceutical adsorption Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-05 Zhaoxuan Feng, Karin Odelius, Gunaratna Kuttuva Rajarao, Minna Hakkarainen
A promising sustainable strategy to valorize cellulose to high-value adsorbents for trace pharmaceuticals, like diclofenac sodium (DCF), in the water is demonstrated. Carbon nanospheres (CN) as the DCF adsorbent were derived from cellulose through a one-pot microwave-assisted hydrothermal carbonization method. CN exhibited efficienct DCF removal (100% removal of 0.001 mg/mL DCF in 30 seconds and 59% removal of 0.01 mg/mL DCF in 1 h). The adsorption kinetics and isotherm data were well-fitted with the pseudo-second-order kinetic model and Langmuir model, respectively. The adsorption process was endothermic and spontaneous as confirmed by the thermodynamic parameters. Multiple characterization techniques including SEM/EDS, FTIR, FTIR-imaging and zeta potential were applied to qualitatively investigate the adsorption process. π-π stacking and hydrogen bonding were proposed as the dominant adsorption interactions. CN also demontrated effective adsorption capacity towards three other commonly-detected contaminants in the wastewater including ketoprofen (KP), benzophenone (BZP), and diphenylamine (DPA), each bearing partial structural similarity with DCF. The affinity of the contaminants towards CN followed the order DPA > BZP > DCF > KP, which could be explained by the different configurations and chemical units. It was speculated that for DCF and KP, the steric hindrance and electrostatic repulsion produced by dissociated carboxyl groups can impede the adsorption process as compared to DPA and BZP. This methodology could offer further insights into the drug adsorption on the cellulose-derived carbon adsorbents and the use of bioderived carbons for treatment of wastewaters contaminated with pharmaceuticals.
Mechanisms for drawdown of floating particles in a laminar stirred tank flow Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-05 He Gong, Fenglei Huang, Zhipeng Li, Zhengming Gao, J.J. Derksen
Particle image velocimetry (PIV) experiments on a laminar stirred tank flow with floating particles at just drawdown conditions were performed. Careful refractive index matching of the two phases allowed to resolve the flow around the particles. The maximum solids volume fraction was 4%. The impeller was a pitched blade turbine with upward and downward pumping modes and with different off-bottom clearances, and the impeller-based Reynolds number ranged from about 50 to 120. Computational fluid dynamics (CFD) coupled to a discrete phase model (DPM) and discrete element method (DEM) was used to predict the flow field, with an emphasis on the tangential velocity component. The liquid velocity profiles predicted by the CFD simulations are in good agreement with the PIV experimental data. The drawdown process and local particle accumulation simulated by the DPM-DEM model agrees with the experimental phenomena as well. Tangential velocity and particles collisions around the shaft trigger the onset of the drawdown of the floating particles.
Pre-magnetization by weak magnetic field enhancing Fe0-Fenton process for wastewater treatment Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-05 Ting Huang, Guangming Zhang, Nan Zhang, Jie Ye, Guang Xian
In this work, the effects of weak magnetic field (WMF) on Fe0 particles were detailedly investigated and the pre-magnetized Fe0-Fenton process was applied to the advanced treatment of citric acids wastewater. The results showed that with WMF pretreatment, the COD removal improved by 38.4%, and the H2O2 consumption reduced by 27.5%. As for the optimal Fe0 pre-magnetization conditions, the time was 30 min and the magnetic field intensity was 200 mT. Pre-magnetization had different impacts on Fe0 with different sizes, only the μm scale Fe0 exhibited the promotion in wastewater treatment. The pre-magnetized Fe0 particles showed good magnetism stability in over 12 h. VSM, BET, SEM, XPS were used to examine the characteristics of the Fe0; results showed that the Fe0 particles had good stability of magnetic property and different size Fe0 had different surface topography. For the first time, it was found that the magnetic memory impacted the energy required for the escape of electrons in depth of the surface iron atoms and resulted in decrease of background intensity in high binding energy. The potential mechanisms of WMF pre-magnetization of Fe0 and application in Fe0-H2O2 reaction were proposed, including the magnetization processing of Fe0 and the inequality reaction on pre-magnetized Fe0 particles in the Fenton process.
Construction of bimetallic Pd-Ag enhanced AgBr/TiO2 hierarchical nanostructured photocatalytic hybrid capillary tubes and devices for continuous photocatalytic degradation of VOCs Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-05 Wenqiang Gao, Xiaofei Zhang, Xiaowen Su, Fulei Wang, Zhihe Liu, Baishan Liu, Jie Zhan, Hong Liu, Yuanhua Sang
Combining high-efficient photocatalysts and well-designed photocatalytic reactors is a promising approach to realize the practical photocatalytic degradation of the volatile organic chemicals (VOCs). In this work, the Pd-Ag/AgBr/TiO2 hierarchical nanostructure was synthesized via a hydrothermal approach followed by the photo-deposition, ion-exchange, and the photo-reduction processes. The bimetallic Pd-Ag co-catalyst on AgBr/TiO2 composites presented enhanced photocatalytic activity in the photo-degradation of propylene, which was varied with Pd content. The high photocatalytic activity of the hybrid photocatalyst is derived from the high visible-light photocatalytic activity of AgBr and the improved charge separation of the Pd-Ag/AgBr/TiO2 hierarchical nanostructure. Finally, a self-container hydrothermal method was proposed and prepared the Pd-Ag enhanced AgBr/TiO2 hierarchical nanostructured photocatalytic hybrid capillary tubes. A well-designed continuous photocatalytic reactor was integrated by fixing the glass capillary tubes onto a pair of circled glass tubes with a Xe arc lamp in the center of the device. The reactor showed a high degradation efficiency of gaseous propylene over a large range of flow rates. Therefore, it possesses a high potential for the practical application to deal with the VOCs.
Evaluation of Single and Multi-component Adsorption of Metronıdazole, Phosphate and Nitrate on Activated Carbon from Prosopıs Julıflora Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-05 S.V. Manjunath, Mathava Kumar
In this investigation, activated carbon was prepared from Prosopis juliflora (PJAC) and characterized using porosimetry, scanning electron microscope (SEM-EDX), Elemental analysis (CHNS), Fourier Transmission-Infrared Radiation (FTIR) and X-ray Diffraction (XRD) analysis. Subsequently, PJAC was used in single (metronidazole (MNZ), phosphate (PO43-) and nitrate (NO3-)) and multi-component adsorption system (MNZ:P:N). As a first step, single-component batch adsorption experiments, i.e. kinetic and equilibrium studies, were conducted at controlled conditions (30°C) and outcomes were used to find out the rate constant and maximum adsorption capacity (qm q m ). The pseudo-second-order kinetic model was found to well represent the removals of MNZ, PO43- and NO3- on PJAC. Among the five isotherm models used, Langmuir isotherm model has predicted qm q m of PJAC for MNZ (17.33 mg/g), PO43- (13.55 mg/g) and NO3- (10.99 mg/g) with good correlation. In addition, the thermodynamic parameters have shown that the adsorption of MNZ, PO43- and NO3- was non-spontaneous, endothermic and increased randomness in nature. In order to quantify the competitive adsorption of a multi-component system, i.e. MNZ, PO43- and NO3-, the batch experiments were conducted in the presence of all three compounds at a ratio of 1:2.5:5 at three different MNZ:P:N concentrations levels (0.1:0.25:0.5, 1:2.5:5 and 10:25:50 mg/L). The modified Langmuir competitive adsorption isotherm model was used to predict the effect of competitive adsorption. In a multi-component system, the maximum adsorption capacities of MNZ and NO3- were decreased by ∼34 and ∼2 times, respectively than single compound system; however, it was increased by ∼1.12 times for PO43-. Overall, the results indicate that PJAC could be used as a potential adsorbent for the removal of emerging pollutants and nutrients.
Graphene-like porous carbon from sheet cellulose as electrodes for supercapacitors Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-05 Ru-Juan Mo, Yang Zhao, Meng-Meng Zhao, Min Wu, Chao Wang, Jin-Pei Li, Shigenori Kuga, Yong Huang
Graphene, a single layer of carbon atoms arranged in an hexagonal lattice, has attracted a lot of well-deserved attention due to its high surface area and excellent electrochemical properties. However, graphene is easy to aggregate and has poor volumetric performance when used as electrode material. Here, dense graphene-like porous carbon (GPC) with hierarchical pore structure was fabricated from sheet cellulose made by milling of bleached kraft pulp. The unique pore structure gave rise to specific surface area value of up to 2045 m2/g, providing aboundant storage sites and channels for electrolyte species. The gravimetric (353 F/g) and volumetric (309.7 F/cm3) specific capacitance at 1 A/g were obtained in 6 M KOH aqueous electrolyte. The gravimetric and volumetric specific energy density of the symmetrical supercapacitor were 120.1 Wh/kg and 80.4 Wh/L, respectively, in an ionic liquid electrolyte in acetonitrile. These excellent performances make this material potentially useful for diverse energy storage devices.
A General Method for High-Performance Li-Ion Battery Ge Composites Electrodes from Ionic Liquid Electrodeposition without Binders or Conductive Agents: the Cases of CNTs, RGO and PEDOT Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-04 Jian Hao, Lei Pan, Hangchuan Zhang, Caixia Chi, Qingjie Guo, Jiupeng Zhao, Yu Yang, Xiaoxu Liu, Xiaoxuan Ma, Yao Li
High-capacity anode materials for lithium ion batteries (LIBs), such as Ge, generally suffer tremendous volume changes, as a result of the conversion reaction mechanism with Li, severely impede the high rate and cycling performance toward their practical application. In this article, we demonstrate a general LIBs Ge composites electrodes fabrication method using electrodeposition from room temperature ionic liquid. Our process is capable of forming composites electrodes with carbon nanotubes (CNTs), reduced graphene oxide (RGO), poly (3, 4-ethylenedioxythiophene) (PEDOT), without the additives and conductive agents. During the electrodeposition process, Ge nanoparticles are integrated into the substrate network. Benefiting from the porosity, conductive network and mechanical stability constructed by interpenetrated compound layers, the hybrid system synergistically enhances the intrinsic properties of each component, yet is robust and flexible. The Ge/CNTs, Ge/RGO and Ge/PEDOT composites retain capacities of ∼851, 1212, and 1300 mAh/g after 200 cycles at 0.1 C. SEM analysis suggests that Ge/PEDOT composites have flower-like hierarchically porous structure, during cycling this structure transforms into a porous network, which can mitigate the physical strains during the Li uptake/release process, and increase the interfacial contact area with organic electrolyte. Consequently, the Ge/PEDOT composites demonstrate greatly enhanced rate capability without obvious capacity fading at high rate of up to 5 C.
Effects of pH adjustment on the hydrolysis of Al-enhanced primary sedimentation sludge for volatile fatty acid production Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-04 Lin Lin, Xiao-yan Li
Aluminum-based chemically enhanced primary sedimentation has seen increasing use in wastewater treatment plants. However, the derived sludge (Al-sludge) has low biodegradability due to the inhibition of Al-coagulants on organic hydrolysis, which increases the difficulty of sludge treatment and limits the potential for resource recovery. In this study, the effects of pH adjustment on the pretreatment and fermentation of Al-sludge was investigated, with a focus on sludge hydrolysis and production of volatile fatty acids (VFAs). The effects of abiotic and biotic hydrolysis on sludge disintegration, organics solubilization, and hydrolytic enzyme activity were also evaluated. The results show that adjustment of the pH to between 8.0 and 10.0 was more effective than adjustment to between 2.0 and 6.0 for sludge hydrolysis and subsequent VFA production. The enzymatic activities of protease and α-glucosidase showed a positive correlation with the pH values, leading to the highest VFA yield (275 mg-COD/g-VS) for the initial pH 10.0 condition, with 46% improvement over the control reactor (without pH adjustment). Semi-continuous fermentation was found to be more effective than batch fermentation for the biotic hydrolysis rate, kH. Little phosphorus (<0.1 mg/L) was released from the Al-sludge into the fermented sludge liquor, so P removal was not necessary before the VFAs were used. The wastewater treatment process with Al-based chemically enhanced primary sedimentation and pH adjustment for enhanced sludge fermentation can recover 24% of organic carbon from domestic wastewater.
On-line mini-column flow injection electrochemical method for researching on resuscitation and dehydration performance of deeply-fouled cation-exchange resins Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-04 Li Yong-Sheng, Li Qiao-Jing, Huang Bo, Gao Xiu-Feng
For rapidly and accurately obtaining the performance parameters of ion-exchange resins, an especial online column flow-injection electrochemical method and system (FIA-ECM) was designed. In the research, the waste strong acid type cation-exchange resin (WSCR) was used as test sample, which was again immersed in the saturated ferric trichloride solution and lubricant oil for long time and heated at 110°C to further deteriorate its ion-exchange performance. And then, the orthogonal and the single factor experiments on WSCR were conducted by using the FIA-ECM system. Under optimized conditions, the resuscitation rate of WSCR reached to 90% which can reuse in industry for various water treatments. Besides, a new conclusion was also obtained by using the FIA-ECM system, namely, exchange capacity of SCR being in drying state is higher than that in wetting state, and new SCR can be transported and saved in drying state, thus can notably reduce transport costs. The conclusion has very important significance in water treatment industry using resins. Merits of FIA-ECM were higher in automation extent, lower in reagent consumption in the test, inexistent in personal errors, and conducive to environmental protection. It can be extended to automatically and rapidly determine performances of various resins or new developed materials with cation-ion exchange capacity and screening of various revitalizers for resins.
Convective mixing of miscible liquids in a rotor-stator spinning disk reactor Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-03 Hitoshi Toma, Koichi Nishino
Convective mixing of two miscible liquids injected into a rotor-stator spinning disk reactor (RS-SDR) has been studied using an LIF technique and CFD simulations. The fluids are ammonia water and fluorescein ammonia water solutions. The RS-SDR has a rotor 100 mm in diameter and a thin circular cavity 0.10-0.15 mm in height between the rotor and stator. Laminar flow conditions for rotation speeds up to 120 rpm and total flow rates up to 8 mL/min are considered. The fluorescein solution is injected from the second off-center hole into the cavity filled with the ammonia water supplied from the central hole. The LIF technique visualizes a spiral streak pattern formed downstream of the second injection hole. This streak pattern is analyzed to calculate the local mixedness of the two fluids. It is determined that the mixedness increases for lower flow rates, while it is less sensitive to rotation speed and cavity height. The CFD simulations indicate that the spiral streak pattern is deformed and stretched in the radial direction to form a densely layered structure of the two fluids. The development of the mixedness along the streak pattern is correlated well with Reinlet/Recavity Re inlet / Re cavity , where Reinlet Re inlet and Recavity Re cavity are the Reynolds numbers for the injected flow and the azimuthal flow in the cavity, respectively. This Reynolds number ratio is shown to be related to the Rossby number and the position and radius of the second injection hole. The proposed correlation is based on a linear combination of injection mixing and rotation mixing. The mixedness decreases with Reinlet/Recavity Re inlet / Re cavity because the injection mixing decreases with Reinlet Re inlet while the rotation mixing increases with Recavity Re cavity .
Dramatically enhanced strain- and moisture-sensitivity of bioinspired fragmentized carbon architectures regulated by cellulose nanocrystals Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-03 Huaquan Wang, Hongsheng Luo, Huankai Zhou, Xingdong Zhou, XinXing Zhang, Wenjing Lin, Guobin Yi, Yihang Zhang
Although flexible conductive polymeric sensors responding to different stimulus have been extensively explored, it remains challenge to integrate high multi-stimuli sensitivity into one material. Herein, novel electromechanical sensors were fabricated, exhibiting dramatically enhanced strain- and water/moisture- sensitivity. The hybridized nano carbons of graphene and carbon nanotubes (CNTs) were regulated with cellulose nanocrystals (CNCs), followed by embedding into the polymeric elastomer via transfer process. The CNCs not only fragmentized the electromechanical networks under external stress, but also amplified the swelling effect on the conductivity variation as exposed upon water/moisture due to the mechanical reinforcement and amphiphilic nature. Micro/nano cracks were generated on the conductive surface layer, enabling dramatic enhancement on the sensitivity and reversibility in the strain sensing. The gauge factor was up to 1129 within 20 % of the strain, which was higher by 182 times compared to that of the control sample without the CNCs content. Moreover, the electromechanical sensors improved the water/moisture sensing whose sensitivity was enhanced by 65 times due to the micro/nano cracks in the fragmentized carbon architecture. The findings extend the application of natural cellulose to exploit multi-stimuli responsive electronics and provide a facial strategy to optimize the sensory performance, which may greatly benefit the developments of the flexible and wearable electronics.
Absorption rates of carbon dioxide in amines in hydrophilic and hydrophobic solvents Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-03 Aravind V. Rayer, Paul D. Mobley, Mustapha Soukri, Thomas R. Gohndrone, Jak Tanthana, Jim Zhou, Marty Lail
The rate of absorption of CO2 into amines in hydrophilic and hydrophobic solvent mixtures was studied in this work using a stopped-flow apparatus and a stirred-tank reactor. Monoethanolamine (MEA, primary amine) and N-methyl benzylamine (NMBZA, aromatic secondary amine) are chosen for this study and diluted in hydrophobic or hydrophilic solvents at different temperatures (295-343 K) and concentrations (0.01-4 kmol.m-3). It was found that the reaction rate between the secondary amine and CO2 in water is faster than the reaction with the linear primary amine (MEA); however, in an ethereal hydrophobic non-aqueous system the NMBZA-CO2 reaction is slower than the reaction of CO2 with MEA. With respect to amine, the reaction orders were found to be 0.9 and 1.2 for hydrophilic systems (MEA + H2O, NMBZA + H2O). For hydrophobic system they were found to be 0.6 and 2.7 (NMBZA + ethereal hydrophobic solvent, NMBZA + MePhOH + ethereal hydrophobic solvent). When amine was mixed with hydrophilic solvent (H2O), the activation energy of amine (NMBZA) to react with CO2 was found to be 27.66 kJ.mol-1 and decreased to 10.37 kJ.mol-1 when mixed with hydrophobic solvent (ethereal hydrophobic solvent). The activation energy of hydrophobic solvent was found to increase by adding an alcohol to the solvent (MePhOH + ethereal hydrophobic solvent). Both the zwitterion and termolecular mechanism were applied to the experimental data. It was found that deprotonation of the zwitterion and deprotonation of the loosely bound complex was the rate limiting step for the zwitterion and termolecular mechanism, respectively. Additionally, activators such as water, piperazine (PZ), and 4-hydroxy piperidinol (HPIP) were added to the ethereal hydrophobic non-aqueous solvent to determine the effect on the reaction rate. It was found that the water- and amine-based activators lead to an increase in the observed reaction rates as the concentration of the activators increased. The reaction of NMBA with CO2 and PZ exhibited a higher reaction rate but the PZ was insoluble in the non-aqueous NMBZA system, whereas HPIP remained soluble and offered a similar reaction rate. The activation energy of ethereal hydrophobic non-aqueous solvent to react with CO2 increased from 27.98 to 32.83 kJ.mol-1 by adding PZ and 33.51 kJ.mol-1 by HPIP and remained by adding H2O (26.78 kJ.mol-1). From this work, it was found that the non-aqueous solvent plays an important role in the reaction rate of CO2 with amines. Activators and solvents can be selected to increase the reaction rate with CO2.
Ferric ion pair mediated biomass redox flow fuel cell and related chemical reaction kinetics study Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-01 Xihong Zu, Lele Sun, Jian Gong, Xiaochun Liu, Yangxi Liu, Xu Du, Wei Liu, Lifen Chen, Guobin Yi, Weigang Zhang, Wenjing Lin, Weizhao Li, Yulin Deng
Highly ordered Au-Ag alloy arrays with tunable morphologies for surface enhanced Raman spectroscopy Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-01 Zhezhe Wang, Xin Wen, Zhuohong Feng, Lin Lin, Ruihua Liu, Pingping Huang, Guilin Chen, Feng Huang, Zhiqiang Zheng
Design of Novel 3D Flower-like Neodymium Molybdate; An Efficient and Challenging Catalyst for Sensing and Destroying Pulmonary Toxicity Antibiotic Drug Nitrofurantoin Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-01 J. Vinoth Kumar, R. Karthik, Shen-Ming Chen, Kuang-Hsiang Chen, Subramanian Sakthinathan, V. Muthuraj, Te-Wei Chiu
Modelling the Synthesis of Nanoparticles in Continuous Microreactors: the Role of Diffusion and Residence Time Distribution on Nanoparticle Characteristics Chem. Eng. J. (IF 6.216) Pub Date : 2018-04-01 Luca Panariello, Luca Mazzei, Asterios Gavriilidis
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