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  • Facile and scalable synthesis of nitrogen-doped ordered mesoporous carbon for high performance supercapacitors
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Lei Fan, Peizheng Sun, Li Yang, Zhilong Xu, Jie Han

    Abstract Nitrogen-doped carbon has been receiving tremendous research interest due to its exotic electrochemical performance and catalyzing capability. Nevertheless, large-scale synthesis of ordered, mesoporous, nitrogen-doped carbon for supercapacitors is rarely reported due to the complexity and uncontrollable property of polymerization of carbon/nitrogen precursors. In this work, we report a facile and efficient approach for mass production of nitrogen-doped carbon, with a narrow pore size distribution and a sheet morphology, via a simple solution casting of biomass-based mixture. Upon drying, the gelatin molecules self-assemble into sheets, and guide the homogeneous loading of sacrificial silica nanospheres. Further carbonization and template removal procedures allow the low-cost production of nitrogen-doped carbon sheets in the absence of complex polymerization. As a result, nitrogen-doped carbon sheets possess a high nitrogen content and ordered, interconnected mesoporous channels, with porosity parameters being carbonization temperature and template size dependence. Additionally, nitrogen-doped, ordered carbon sheets exhibit high performance for supercapacitor application, including high specific capacitances and energy/power densities. This work demonstrates a unique route to synthesizing ordered mesoporous nitrogen-doped carbon sheets via a scalable, low-cost method, which may shed light on many other applications aside from energy storage, such as water splitting, catalysis and sensor.

    更新日期:2020-01-26
  • Electrochemical characteristics of high-capacity Mg/V 2 O 5 hybrid batteries with Mg-Li dual salt electrolytes
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Haebeen Kim, Duri Kim, Min Young Hong, Ji Heon Ryu

    Abstract Mg-Li hybrid cells are constructed and evaluated using a V2O5 positive electrode, a Mg metal negative electrode, and Mg-Li dual salt electrolytes. When a crystalline V2O5 (c-V2O5) and an Al current collector are used, side reactions can occur even at the upper voltage limit of 2.4 V (vs. Mg/Mg2+). However, when an amorphous V2O5 (a-V2O5) is used with a Ti current collector, the side reactions are greatly reduced and the cycle performance is improved. The discharge capacity and Coulombic efficiency at the second cycle are 187 mA h g−;1 and 94.9%, respectively. a-V2O5 is more electrochemically stable than c-V2O5, the Mg/a-V2O5 cell shows a discharge voltage of ∼1.5 V and a specific capacity of 148 mA h g−1 even after 20 cycles. Therefore, the a-V2O5 is a potential host material for Mg-Li hybrid batteries.

    更新日期:2020-01-26
  • Carbon supported palladium-copper bimetallic catalysts for promoting electrochemical oxidation of formic acid and its utilization in direct formic acid fuel cells
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Jongwon Yang, Seungwon Yang, Yongjin Chung, Yongchai Kwon

    Abstract Carbon supported palladium-copper (Pd-Cu) bimetallic catalysts (PdxCuy/Cs) are fabricated by modified polyol method to enhance the reaction rate of formic acid oxidation reaction (FAOR) and the performance of direct formic acid fuel cell (DFAFC) through weakening the bond with the intermediate of formic acid. According to the evaluations, when the ratio of Pd and Cu is 3 : 1 (Pd3Cu1/C), catalytic activity is best. Its maximum current density is 1.68-times better than that of commercial Pd/C. Even from the optical and spectroscopic characterizations, such as TEM, EDS, XPS and XRD, Pd3Cu1/C shows an optimal particle size and a higher degree of alloying. This is because in Pd3Cu1/C catalyst, the d-band center that induces the weakening in adsorption of formate anion groups to Pd surface is most positively shifted, and this positive shift promotes the reaction rate of FAOR, which is the rate determining step. When the performance of DFAFCs using the PdxCuy/C catalysts is measured, the maximum power density (MPD) of DFAFC using Pd3Cu1/C catalyst is 158 mW cm−2, and this is the best MPD compared to that of DFAFCs using other PdxCuy/C catalysts. In addition, in a comparison with commercial Pd/C catalyst, when the same amount of catalyst is loaded, MPD of DFAFC using Pd3Cu1/C catalyst is 22.5% higher than that of DFAFC using commercial Pd/C.

    更新日期:2020-01-26
  • Study of mercury-adsorption behavior in the exhaust gas of KI-impregnated ACF
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    In-Soo Kang, Yo-Seob Shin, Byung Chan Kwon, No-Kuk Park, Tae Jin Lee, Seung Woo Lee, Myung Jo Seo

    This study examined the selective removal of gaseous mercury contained in combustion flue gas by potassium iodide (KI) loaded on activated carbon fibers (ACF). Activated carbon, such as ACF, although a useful mercury sorbent, shows poor performance in the direct treatment of high-temperature flue-gases because it removes mercury only by physical adsorption. KI can remove mercury at high temperatures via a gas-solid reaction between mercury and adsorbents, and it has been confirmed experimentally that it shows high mercury removal performance in the temperature range of 100–200 °C. On the other hand, KI in the absence of a porous support with a high surface area has low mercury-adsorption removal efficiency. Hence, a high surface area support is needed for adsorption removal. In the present study, mercury contained in combustion exhaust gas could be removed efficiently using KI as an adsorption activity enhancer on an activated carbon fiber (ACF), which provided a high surface area.

    更新日期:2020-01-08
  • Gas hydrate formation by allyl alcohol and CH 4 : Spectroscopic and thermodynamic analysis
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Ki Hun Park, Minjun Cha

    Abstract We discovered a new structure II (sII) hydrate forming agent, allyl alcohol (AA), in the presence of methane (CH4) for the first time, and characterized the crystal structure, guest distribution, and phase equilibria of the (AA+CH4) hydrate. Using solid-state 13C NMR and Raman spectroscopy, the crystal structure of the (AA+CH4) hydrate was confirmed to be a sII hydrate, and the CH4 molecule was found to be encapsulated in both the large and small cages of the sII hydrate. In addition, AA was found to be included in the large cages of the sII hydrate in the Gauche-Gauche form based on the measured- and calculated-NMR spectra. Notably, we investigated the free OH signal of AA in the Raman spectra to determine whether hydrogen bonding occurred between host and guest molecules; however, we could not determine whether the existence of the free OH signal was consistent with this host-guest interaction. To clearly identify the crystal structure and possible host-guest interactions, a high-resolution powder X-ray diffraction (HRPD) pattern of our (AA+CH4) hydrate sample was analyzed using Rietveld analysis with the direct space method. The crystal structure of the (AA+CH4) hydrate was assigned as the cubic Fd3m structure with a lattice constant of 17.1455 Å. In particular, the shortest distance between the AA molecule in the hydrate cages and an oxygen atom in the host water was estimated to be 2.55 Å; thus, we concluded that the hydroxyl group of the AA molecule was hydrogen-bonded to the host water framework. Finally, we measured the phase equilibrium conditions of the binary (AA+CH4) hydrate and found that the equilibrium pressure conditions of the binary (AA+CH4) hydrate were slightly higher than those of the pure CH4 hydrate.

    更新日期:2020-01-08
  • Effect of surfactant on wetting due to fouling in membrane distillation membrane: Application of response surface methodology (RSM) and artificial neural networks (ANN)
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Bomin Kim, Yongjun Choi, Jihyeok Choi, Yonghyun Shin, Sangho Lee

    Membrane wetting is a bottleneck that limits the widespread application of membrane distillation (MD) technologies. However, the prediction of membrane wetting is difficult, due to its unpredictable behavior with the chemical species in feed waters. We used response surface methodology (RSM) and artificial neural networks (ANN) to predict the wetting phenomena in direct contact membrane distillation (DCMD) for the treatment of synthetic wastewater. Experiments were performed at various concentrations of NaCl, CaSO4, humic acid, alginate, and sodium dodecyl sulfate (SDS) to examine their effects on the wetting. The RSM and ANN models were established using the experimental data and statistically validated by the analysis of variance (ANOVA). The results showed that both RSM and ANN are able to predict the time of wetting and recovery for the range of input variables. The model predictions suggested that the concentration of NaCl and SDS has the greatest influence on the prediction parameters. When the concentration of SDS was less than 5 mg/L, the concentration of NaCl was the dominant role in the wetting. On the other hand, the concentration of SDS was the predominant factor when the concentration of SDS was higher than 5 mg/L.

    更新日期:2020-01-08
  • Direct synthesis of H 2 O 2 over Pd/C catalysts prepared by the incipient wetness impregnation method: Effect of heat treatment on catalytic activity
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Vu Thi Thuy Hang, Young-Min Chung

    Although various Pd/C catalysts have been applied in the direct synthesis of H2O2, unsatisfactory H2O2 yields have been achieved. We systematically investigated the effect of heat treatment on the physicochemical properties of Pd/C catalyst, and thereby on the catalytic performance in the direct synthesis of H2O2. Pd/C catalysts prepared by the incipient wetness method were subjected to different heat treatments and applied in H2O2 synthesis. The calcination temperature was found to have a key role in determining the Pd nanoparticle (NP) size; calcination at 523 K yielded highly oxidized and small Pd NPs corresponding to the sub-nano domain (1.4–2.5 nm). This Pd/C catalyst is superior not only in promoting H2O2 formation, but also in suppressing the subsequent unfavorable H2O2 decomposition and hydrogenation, which explains its excellent H2O2 productivity (as high as 4,443 mmol H2O2/g Pd·h) and selectivity (94.5%). On the other hand, the reaction performance of the Pd/C catalysts calcined at a higher temperature (673 K) or reduced under hydrogen was sharply reduced owing to the formation of larger Pd NPs or the enhancement of the metallic nature of Pd, respectively The amount of residual Cl ion on Pd/C catalyst after heat treatment also had an impact on the catalytic activity as it affected the pH of reaction solution. These results clearly demonstrate that an efficient Pd/C catalyst can be realized by fine tuning the conditions of heat treatment during catalyst preparation.

    更新日期:2020-01-08
  • Remarkable effects of deep eutectic solvents on the esterification of lactic acid with ethanol over Amberlyst-15
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Ayşe Ezgi Ünlü, Azime Arikaya, Aybike Altundağ, Serpil Takaç

    Abstract Deep eutectic solvents (DESs) are widely used in numerous reactions both as a solvent and a catalyst. In this study, different types of DESs were investigated as a supplementary component for Amberlyst-15 to enhance its catalytic activity in the esterification reaction of lactic acid with ethanol. The effects of the following parameters such as DES type, choline chloride: glycerol (ChCl-Gly) (1 : 2) amount, molar ratio of reactants, temperature and agitation rate on the initial rate of reaction and yield of ethyl lactate were investigated. According to the results, DESs alone did not have any catalytic effect on the esterification; however, DESs together with Amberlyst-15 provided a significant increase in the initial rate of reaction and yield. The activation energy of the reaction decreased significantly with the combined use of Amberlyst-15 and ChCl-Gly (1 : 2). Internal and external mass transfer limitations were found to be negligible under optimum reaction conditions.

    更新日期:2020-01-08
  • Low temperature adsorption of nitric oxide on cerium impregnated biomass-derived biochar
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Shahreen Izwan Anthonysamy, Pooya Lahijani, Maedeh Mohammadi, Abdul Rahman Mohamed

    Abstract This study investigates the catalytic oxidation of NO to NO2 over biomass-derived biochar at ambient temperature. Rubber seed shell (RSS) was used as lignocellulosic waste to develop biochar for NO capture. The NO adsorption capacity of pristine biochar was low, about 17.61 mg/g at 30 oC. To enhance the NO uptake capacity of biochar, cerium (Ce) was introduced into the biochar surface through simple impregnation method. Upon this, the NO adsorption capacity of 3 wt% Ce-loaded biochar profoundly increased to 75.59 mg/g at the same adsorption condition. This was confidently due to the excellent oxygen storage capacity of ceria which could react with free active sites on the biochar surface to form oxidized cites C(O). Characterization results indicated that the adsorbed species was in the form of -O-N=O, suggesting that the adsorption of NO was followed by reaction with surface oxidized sites to form NO2. Studying the kinetics of the NO adsorption using pseudo-second order, Avrami and Elovich models showed that chemisorption was the chief mechanism that governed the adsorption process and the activation energy for NO adsorption was estimated to be around −45 kJ/mol.

    更新日期:2020-01-08
  • Flow characteristics within the wall boundary layers of swirling steam flow in a pipe comprising horizontal and inclined sections
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Afrasyab Khan, Mohd Sobri Takriff, Masli Irwan Rosli, Nur Tantiyani Ali Othman, Khairuddin Sanaullah, Andrew Ragai Henry Rigit, Ajmal Shah, Atta Ullah

    Handling and utilization of steam flow efficiently to obtain various tangible industrial outcomes relies mainly upon how to optimize various flow parameters like boundary layer thickness, skewness, shear stress, and turbulent dissipation for minimum losses such as pressure and heat. Swirling steam flow, driven by a propeller through a circular duct along horizontal and inclined surfaces presents an interesting flow regime that includes the boundary layer flows close to the wall of the pipe and weak and uniform flow that prevails across the inner region of the pipe. Such flow was investigated here with a specially designed experimental facility. Convective Instabilities were observed that propagate along the axial direction in a nonlinear fashion. It was observed that the operating conditions could be optimized for measuring the shear stresses based on the intersection of the profiles under the effect of variations in the inlet pressure of steam and the rotational speed of the propeller. We found that the flow transformed from positive to negative skewness when the rotational speed of the propeller was raised from 4–14 thousand per minute at 10 bars of constant inlet steam pressure. More area came under the effect of reduced skin friction when the rotational speed of the propeller was raised. More turbulent energy was found to be dissipated when the rotational speed of the propeller was raised. It was found that yet the dissipation of the turbulent energy takes place under the joint effect of inlet pressure of steam and the rotational speed of the propeller, but the exact effect of any one of these two operating parameters still needs to be determined and requires further investigation.

    更新日期:2020-01-08
  • Magnetic nanocomposite of filamentous algae activated carbon for efficient elimination of cephalexin from aqueous media
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Shirin Afshin, Yousef Rashtbari, Bahman Ramavandi, Mehdi Fazlzadeh, Mehdi Vosoughi, Seyad Ahmad Mokhtari, Mohammad Shirmardi, Rabia Rehman

    Discharge of antibiotics into the environment can cause problems like increase of the microorganisms’ resistance, disturbing the ecological balance and increasing the allergy in humans. In this research, an activated carbon was produced from filamentous algae and then magnetized with Fe3O4. The adsorbent size was nano-scale and its characteristics were studied using XRD, FT-IR, FE-SEM, BET and VSM techniques. The response surface method (RSM) was employed to optimize the operating parameters and determine the best conditions for cephalexin removal by novel composite of AC-Fe3O4. The various parameters in the process, such as reaction time, initial pH, adsorbent dose, initial concentration of cephalexin and effect of cations and anions that could interfere in the adsorption of cephalexin were evaluated in three levels. The proposed quadratic model was found to be best suggested model for the adsorption process (R2=0.99094 and \({\rm{R}}_{adj}^2=0.9991\)). According to results, the parameters such as cephalexin concentration, the adsorbent dose, the reaction time and the pH value were found to be 28.16 mg/L, 2 g/L, 30.04 and 3.02, respectively. Experimental results showed that the adsorption of cephalexin followed Langmuir isotherm (R2=0.9803). Also, the results showed cephalexin adsorption on the composite fitted pseudo-second-order kinetics. The study showed that the AC-Fe3O4 adsorbent has high efficacy for eliminating cephalexin from aqueous solution.

    更新日期:2020-01-08
  • Application of amine-functioned Fe 3 O 4 nanoparticles with HPEI for effective humic acid removal from aqueous solution: Modeling and optimization
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Seyedeh Mahtab Pormazar, Mohammad Hassan Ehrampoush, Mohammad Taghi Ghaneian, Mehdi Khoobi, Parvaneh Talebi, Arash Dalvand

    Abstract Humic acids are one type of natural organic matter and precursors of chloro organic compounds that cause a major problematic issue for water treatment plants. In the present study, Hyperbranched polyethylenimine (HPEI) was grafted onto Fe3O4 nanoparticles for HA adsorption from aqueous solution. Fe3O4@HPEI nanoparticles were characterized via TEM, SEM, FTIR, XRD, VSM, and BET analysis. The effects of various operational parameters including initial HA concentration, pH, adsorbent dose, contact time and ionic strength on the HA removal were assessed. According to the obtained statistical model, the optimal condition was acquired at the initial HA concentration 79 mg/L, adsorbent dose 0.128 g/L, pH 3 and contact time 29 min, which up to 97.27% HA were adsorbed by Fe3O4@HPEI that was close to the predicted result by the model (95.6%) that confirmed the validity of the selected model. The adsorption data were fitted to the pseudo-second-order kinetic and Freundlich isotherm. Thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic. The fabricated Fe3O4@HPEI nanoparticles could be repeatedly utilized as a suitable adsorbent to remove HA from the aqueous environment.

    更新日期:2020-01-08
  • Molecular investigation of amine performance in the carbon capture process: Least squares support vector machine approach
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Bijan Rezaei, Siavash Riahi, Ali Ebrahimpoor Gorji

    The growing threat of global warming has raised more attention towards carbon capture. Current amine plants used for carbon removal suffer from great costs inflicted by high energy demand of the solvent regeneration step. Recently, looking for amines with proper performance in reduced temperatures has been the subject of many researches. Clearly, conducting these researches without any criterion and based only on trial and error wastes large amounts of money and time; thus, it is highly needed that the effect of different amine structural parameters be studied on the amine’s cyclic capacity. Quantitative structure property relationship (QSPR) provides an effective method for predicting amines capacity for CO2 absorption. In this work, density functional theory (DFT) was employed for optimization of the molecular geometries, and linear and nonlinear models based on parameters related to the molecular structure are presented. The value of the square of the correlation coefficient (R2) for the MLR and SVM models are 0.894 and 0.973, respectively. Developed models can be used as a criterion for amine selection. Reliability and high predictability of the models are confirmed based on statistical tests. Moreover, mechanistic interpretation of models for better understanding of the reaction mechanism of carbon capture was discussed.

    更新日期:2020-01-08
  • Extraction of reactive dye via synergistic Aliquat 336/D2EHPA using emulsion liquid membrane system
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Raja Norimie Raja Sulaiman, Hilmi Abdul Rahman, Norasikin Othman, Muhammad Bukhari Rosly, Norela Jusoh, Norul Fatiha Mohd Noah

    Abstract Facilitated transport of Orange 3R was performed by means of emulsion liquid membrane (ELM) technique containing double extractants of Aliquat 336 and D2EHPA as extractant and synergist extractant, respectively. Cooking palm oil, sorbitan monooleate (Span 80), and sodium hydroxide were used as diluent, surfactant and stripping agent, respectively. Several parameters influencing the extraction of Orange 3R via ELM, namely effect of extraction time, agitator speed, Span 80 concentration and treatment ratio, were experimentally investigated and optimized using response surface methodology (RSM). Results demonstrated that about 91% of Orange 3R was successfully extracted under optimum conditions of 12 minutes of extraction time, 413 rpm of agitator speed, 3.2% (w/v) of sorbitan monooleate, and 1:9.8 of treatment ratio. Additionally, the aforementioned optimum conditions were found to be more suitable to treat low concentration of Orange 3R (less than 100 ppm) from simulated textile wastewater. The findings reveal that reactive Orange 3R dye is able to be selectively extracted using double extractants via sustainable ELM process as well as providing high potential application in the dye removal from industrial textile wastewater.

    更新日期:2020-01-08
  • Decomposition of indoor VOC pollutants using non-thermal plasma with gas recycling
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Christian Ariane Santos, Nguyen Hoang Phuong, Mi Jeong Park, Sang Bum Kim, Young Min Jo

    Volatile organic compounds in the indoor environment of small businesses (painting workshops, hair salons, nail shops, printing shops, laundries etc.) may result in adverse health effects for both workers and customers. Similarly, VOCs identified in these small businesses are included in the list of ozone precursors that harm the environment. We used a non-thermal plasma reactor with gas recycling to study the decomposition of dilute concentrations of VOCs in air. The non-thermal plasma reactor was a surface dielectric barrier discharge (surface DBD) type, and the target gases were methyl ethyl ketone, toluene and n-hexane at concentrations of 20, 50 and 100 ppmv. Highest decomposition efficiency (97%) was achieved by treating n-hexane at 20 ppmv. Gas recycling had an almost negligible effect during pollutant treatment at varying recycling rates (0-50%). Increasing the input energy resulted in higher decomposition efficiency, but had an inverse effect on the energy yield of the system. Concentrations of CO2 and ozone increased linearly with the increase of energy input in the system. Consumption of ozone for other applications, such as water treatment or coupling the DBD system with an appropriate catalyst, may address this concern.

    更新日期:2020-01-08
  • Recycling of gold from waste electronic components of devices
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Rekha Panda, Om Shankar Dinkar, Manis Kumar Jha, Devendra Deo Pathak

    Tremendous generation of e-waste and its illegal recycling are causing immense threat to environment as well as the loss of precious metals. The present research reports a novel hybrid process for the total recovery of gold from small depopulated components of e-waste. Connectors and integrated circuits (ICs) liberated from printed circuit boards (PCBs) were pulverized and processed for gold leaching using 10 g/L sodium cyanide solution at 40 °C and mixing time 15 min, where more than 95% gold was found to be leached out in single stage. From the obtained leach liquor, gold metal was recovered by charcoal adsorption followed by heat treatment. The raffinate left after adsorption of gold was found to contain ~10 mg/L gold, which was also recovered using Amberlite IRA 400Cl at equilibrium pH 9.6 in 30 min maintaining aqueous/resin (A/R) ratio 25 mL/g. The raffinate solution was enriched to 882.41 mg/L and the solution was further processed to get metal/salt using cementation/ evaporation. Obtained leached residue is processed for non-ferrous metals recovery and finally disposed-off after treatment and TCLP test. The effluent left after leaching could be easily decomposed and treated in ETP using standard environmental procedure.

    更新日期:2020-01-08
  • Catalytic oxidation of benzene over alumina-supported Cu-Mn-Ce mixed oxide catalysts
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Yang Gao, Jun Xiao, Jiandong Ye, Xiaodong Huo, and Yutong Shen

    Based on the response surface methodology (RSM), Cu-Mn-Ce catalysts were prepared via the vacuum impregnation method. Also, Their performance in the oxidation of a tar model compound (Benzene, 5,000 ppm) was evaluated. Results show that the optimum condition is CuO-MnO content of 30% and CeO2 content of 4.4% at a calcination temperature of 620 °C for 4.1 h. In this condition, the confirmatory experiment indicates the average carbon conversion rate within half an hour (Xc-0.5h) and four hours (Xc-4h) are 99.5% and 97.1% at 300 °C, respectively, which is in good agreement with the model prediction. XRD, H2-TPR, SEM, and XPS were employed in catalyst characterization. CuO is the primary active metal in the catalysts, which is affected easily by the calcination temperature. A lower calcination temperature tends to cause a weak structure strength, but a higher temperature results in impairing the reducibility. The major roles of CeO2 are displayed in two aspects that CeO2 increases the dispersion of the active metal, enhances the catalyst stability, and increases the oxygen vacancies and improves the oxygen transfer ability. For Cu-Mn-Ce composite catalyst, the catalytic oxidization of benzene complies with the Mars-van Krevelen mechanism (MVK). The content of CuO-MnO determines the number of active sites on the catalyst, which promotes the reduction of catalyst. CeO2 plays an important role in enhancing the oxidization of the catalyst. Therefore, the ratio of CuO-MnO to CeO2 in the catalyst will cause a change of the control step of the redox reaction.

    更新日期:2020-01-08
  • The effects of radiation on heat and mass transfer of magnetohydrodynamic Marangoni flow in the boundary layer over a disk
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Yanhai Lin, Meng Yang

    This study investigated the problem of radiation effects on the flow heat and mass transfer of magnetohydrodynamic steady laminar Marangoni convection in the boundary layer over a disk in the presence of a linear heat source and first-order chemical reactions. The governing partial differential equations of the disk model were established and transformed to a series of ordinary differential equations via suitable self-similar transformations, which were solved numerically by the shooting technique coupled with Runge-Kutta scheme and Newton’s method. The Marangoni number related to temperature and concentration was derived, the effects of the magnetic Hartmann number, Marangoni number, radiation number, heat source number and chemical reaction number related to velocity, temperature, and concentration profiles were analyzed. The results demonstrate that the Hartmann number and Marangoni number have significant impacts on the heat and mass transfer of the Marangoni boundary layer flow. The temperature tends to increase with heat generation and decrease with heat absorption, and it exhibits a delay phenomenon for significant heat generation cases. Negative/positive chemical reactions tended to increase/decrease the concentration, similar to the effect of heat generation/absorption on the temperature.

    更新日期:2020-01-08
  • Anomaly detection in a hyper-compressor in low-density polyethylene manufacturing processes using WPCA-based principal component control limit
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Byeong Eon Park, Ji Seon Kim, Jeong-Keun Lee, In-Beum Lee

    Abstract Low-Density Polyethylene (LDPE) was synthesized from ethylene at high-temperature and pressure condition. Hyper-compressor used to increase pressure up to 3,500 atm should be monitored and controlled delicately or it cannot guarantee stable operation of the process causing process shutdown (SD), which is directly related to product yield and process safety. This paper presents a data-based multivariate statistical monitoring method to detect anomalies in the hyper-compressor of a LDPE manufacturing process with weighted principal component analysis model (WPCA), which can consider both time-varying and time-invariant characteristic of data combining principal component analysis (PCA) and slow feature analysis (SFA). Operation data of the LDPE manufacturing process was gathered hourly for four years. WPCA-based principal component control limit (PCCL) was used as an index to determine anomaly and applied to five emergency shutdown (ESD) cases, respectively. As a result, all the five anomalies were detected by a PCCL, respectively, as a sign of SD. Moreover, it shows a better anomaly detection performance than the monitoring method using T2 and squared prediction error (SPE) based on PCA, SFA, or WPCA.

    更新日期:2020-01-08
  • The effect of calcium peroxide originating from oyster shell powder on control of phosphorus compounds in oceanic sediment
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2020-01-08
    Beom-Geun Kim, Md Akhte Khirul, Daechul Cho, Sung-Hyun Kwon

    This study evaluated the water quality above the marine sediment by inputting oxygen releasing compound (ORC) processed from calcined oyster shells. Presumed vital parameters such as DO, pH, ORP, chlorophyll-a and classified phosphorous compounds were monitored for 20 d. ORP decreased with time in the control bed, while it increased to a positive value as a result of the ORC effect. DO kept showing a relatively high concentration in ORC treated column. We observed an increase of chlorophyll-a and a decrease of dissolved inorganic phosphate (DIP) simultaneously, which meant the released inorganic phosphorus would convert to an organic form in the overlying water. TP rises were the lowest in the ORC column (79%), meanwhile in the control column those went up to 0.304 mg/L (85%). Also, phosphorus fractions were measured in the sediment: Fe-P decreased in control while Fe-P and Ca-P soared greatly in the ORC column. This implies that in more oxidized environment inorganic phosphate bound to Ca-species would be eliminated as solidified precipitates in the sediment pore water, and it consequently suppressed the release of phosphates to the overlying water. The results indicate that the release of phosphorus and resulting eutrophication could be effectively controlled via the local environment improved by calcined ORC.

    更新日期:2020-01-08
  • Controlling the recombination of electron-hole pairs by changing the shape of ZnO nanorods via sol-gel method using water and their enhanced photocatalytic properties
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Yong Sik Seo, Seong-Geun Oh

    Abstract ZnO nanorods were prepared through a sol-gel process by adding various amounts of water at low temperature and atmospheric pressure conditions for application as a photocatalyst. The 1-D ZnO nanostructures can overcome fast recombination of photogenerated electrons and holes that inhibits photocatalytic efficiency. X-ray diffractometer and transmission electron microscopy measurements confirmed that the (002)/(100) intensity ratio increased from 0.83 to 1.34 and the morphology of the ZnO nanoparticles was changed from a spherical shape to nanorods with the addition of water. UV-vis spectroscopy showed a red shift from 360 nm to 371 nm, which indicates a decrease of the band gap energy. PL measurements of the ZnO nanorods showed a 103 times improvement of the NBE/DLE intensity ratio compared to the ZnO nanospheres. When the photocatalytic efficiency of the ZnO nanoparticles was estimated for the degradation of methylene blue dye under irradiation of UV light, the photocatalytic kinetic constant increased from 0.067 min−1 to 0.481 min−1. As a result, longer ZnO nanorods showed better photocatalytic performance.

    更新日期:2020-01-06
  • Modified kinetic rate equation model for cooling crystallization
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Yuntae Jin, Kiho Park, Dae Ryook Yang

    The kinetic rate equation (KRE) model, unlike the population balance equation model, can describe growth, nucleation, and even Ostwald ripening simultaneously. However, the KRE model cannot be applied in cooling crystallization systems. In this work, we propose a modified KRE model to describe cooling crystallization. The modified KRE model can successfully describe crystal growth and nucleation in cooling crystallization systems. In addition, the metastable zone width was simulated using the modified KRE model and compared with the experimental data in references. The results revealed that the modified KRE model could express the effect of overheating prior to cooling on the metastable zone width. As the extent of overheating increases, the metastable zone width becomes wider, which phenomenon can be clearly simulated by the modified KRE model. This modeling capability is attributed to the behavior of particle clusters that are sized less than the size of sub-nuclei. Because the population balance equation model cannot describe the metastable zone width, the modified KRE model has certain competitive advantages in its application to various crystallization systems.

    更新日期:2020-01-06
  • Green and low-cost preparation of CIGSe thin film by a nanocrystals ink based spin-coating method
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Trang Thi Thuy Le, Nam Le, Mohan Reddy Pallavolu, Yoonchang Jeon, Dong-seob Jeong, Babu Pejjai, Vasudeva Reddy Minnam Reddy, Nguyen Tam Nguyen Truong, Chinho Park

    Abstract An “ink” solution based process, using spin-coating technique, followed by annealing in selenium environment with different temperature programs was utilized to prepare CIGSe thin films. Herein, the CuIn0.7Ga0.3Se2 nanocrystals were synthesized using ethanol — a “green” solvent. Three different solvents: 2-propanol, 2-methoxyethanol, and their 2: 1 mixture (v/v ratio), were investigated as a dispersion medium for the as-synthesized CIGSe nanocrystals to form a stable ink solution. The last one- a mixture of 2-propanol: 2-methoxyethanol=2: 1 (v/v), was found to be the most suitable. Furthermore, the influences of various annealing modes on the CIGSe grain size and density in the resulting film were also studied. The as-prepared CIGSe thin film was around 1 µm thick and possessed a tetragonal structure. A newly developed cheaper and “greener” non-vacuum process was applied successfully from the synthesis of nanocrystals to the formation of ink solution, and produced high quality thin films; this opens a new route to the cost-competitive commercialization of CIGSe thin film solar cells.

    更新日期:2020-01-06
  • Facile fabrication and photocatalytic activity of Ag/AgI/rGO films
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Sooyeon Jang, Sung Min Lee, Jin Seon You, Hyung-Jun Koo, Suk Tai Chang

    The composite material, Ag/AgX/graphene (X=Br, Cl, I), is considered a promising photocatalyst for photocatalytic degradation of organic pollutants. Its photocatalytic activity is superior to that of the conventional TiO2 photocatalyst; the enhanced photocatalytic activity is attributed to its effective charge separation ability and wide visible light absorption. However, the Ag/AgX/graphene composite is often prepared in the powder form, limiting its wide-spread application. In addition, the simple fabrication of Ag/AgX/graphene composite films is highly challenging. In this study, a simple solution-based process based on meniscus-dragging deposition is demonstrated for the fabrication of Ag/AgI/rGO composite films. Uniform catalyst films with reasonable photocatalytic activities can be easily fabricated by using this microliter-scale solution process.

    更新日期:2020-01-06
  • Rapid and reusable detection of hydrogen peroxide using polyurethane scaffold incorporated with cerium oxide nanoparticles
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Pathikrit Saha, Anoth Maharajan, Pritam Kumar Dikshit, Beom Soo Kim

    We report a novel approach to using a polyurethane scaffold incorporated with cerium oxide nanoparticles as an alternative to the natural enzyme horseradish peroxidase for rapid and reusable detection of hydrogen peroxide. After the preparation of polyurethane from soybean oil and malic acid, cerium or iron oxide nanoparticles were synthesized and incorporated into the polyurethane scaffold by ultrasonic treatment. Formation of nanoparticles was characterized using Fourier transform infrared, transmission electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. Iron oxide nanoparticles (FeONPs) with an average size of 50 nm were not uniformly integrated; however, spherical cerium oxide nanoparticles (CeONPs) with an average size of 14 nm were easily incorporated into the polyurethane scaffold. The CeONP-incorporated polyurethane scaffold was highly responsive (<10 s) to H2O2, with a limit of detection of 3.18 µM, and was reusable for at least ten cycles without significant loss of detection activity. However, the response time of CeONP solution was more than 5 min. Both FeONP solution and FeONP incorporated polyurethane scaffold were poor at detecting H2O2.

    更新日期:2019-12-11
  • Microwave assisted persulfate induced degradation of sodium dodecyl benzene sulfonate
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Pravin Sukharaj Bhandari, Parag Ratnakar Gogate

    Microwave assisted persulfate induced degradation of sodium dodecyl benzene sulfonate (SDBS) was investigated, focusing on establishing the best conditions for maximum degradation. The study involving different persulfate based oxidants, such as potassium persulfate (KPS), ammonium persulfate (NH3PS) and sodium persulfate (NaPS), revealed that the extent of degradation as 98.3, 82.2 and 68.2% was obtained for the use of KPS, NH3PS and NaPS, respectively. The study of the effect of SDBS concentration (25–100 mg/L), oxidant loading (0–3 g/L) and power (140–350 W) established that degradation decreased with an increase in the operating parameter beyond the optimum condition. Under optimized conditions using potassium persulfate (KPS) as an oxidant, 51.6% and 98.3% degradation of 50 mg/L SDBS solution was obtained by conventional and microwave assisted chemical oxidation approach, respectively, under optimized conditions of power, oxidant loading, volume and time maintained as 280 W, 2 g/L, 250 mL and 28 min, respectively. Extending the conventional approach for 120 min resulted in degradation of 92.5%, which establishes that microwave helps in reducing the treatment time significantly. Kinetic study revealed pseudo-first-order behavior for degradation of SDBS. Energy per order (EEO) for conventional and microwave assisted degradation was observed to be 840 and 317.33 kWh/m3, respectively. Overall, microwave assisted persulfate induced degradation of SDBS has been established to be promising method giving rapid degradation and better economics.

    更新日期:2019-12-11
  • Precursor and dispersion effects of active species on the activity of Mn-Ce-Ti catalysts for NO abatement
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Xiaobo Wang, Jie Zhou, Caojian Jiang, Jia Wang, Keting Gui, Hywel Rhys Thomas

    Mn-Ce-Ti catalysts were prepared by different precursors (including manganese nitrate, manganese acetate, and manganese chloride) and used for selective catalytic reduction (SCR) of NO with ammonia. The relationships among the structure, physicochemical properties, and catalytic activity were explored by N2 adsorption/desorption, X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR), NH3-temperature programmed desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), scanning electron microprobe (SEM) and energy dispersive spectroscopy (EDS) techniques. The results show that the different Mn precursors play important roles in the catalytic activity. The Mn-Ce-Ti(N) catalyst synthesized by manganese nitrate precursor exhibits the best catalytic activity, while the Mn-Ce-Ti(C) and Mn-Ce-Ti(Cl) catalyst prepared by manganese acetate and manganese chloride, respectively, exhibit relatively low catalytic activity. The manganese nitrate precursor could promote the specific surface area and redox ability, enhance the amounts of Brønsted and Lewis acid sites, and enrich the surface active species such as Mn4+, Ce3+ and surface chemisorbed oxygen of the catalyst, all of which will contribute to the SCR performance. Moreover, the Mn-Ce-Ti(N) catalyst possesses highly dispersed and uniform surface active species, which will result in the optimal physicochemical properties and superior catalytic performance.

    更新日期:2019-12-11
  • Oxygen transfer capacity of the copper component introduced into the defected-MgMnAlO 4 spinel structure in CH 4 -CO 2 /air redox cycles
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Namgyu Son, Jeong Yeon Do, No-Kuk Park, Ui Sik Kim, Jeom-In Baek, Doyeon Lee, Ho-Jung Ryu, Misook Kang

    Oxygen carrier particles were fabricated by using defected-MgMnAlO4 as a support particle with crystal defects, and by the Cu2+ ions with a higher reduction potential substituted with Mg2+ ions, in order to use methane-chemical looping combustion (CH4-CLC) reaction. The oxygen transfer capacities of the particles were compared when conducting redox reactions under H2/air or CH4-CO2/air systems. As a result, the oxygen transfer capacity increased as the amount of Cu ions added increased. In particular, in the CH4-CO2/air system, Cu0.75Mg0.25MnAlO4 particle showed an excellent oxygen transfer capacity of 7.62%. The XPS result confirms that the Cu2+ (also partially Mn3+ ions) in the Cu0.75Mg0.25MnAlO4 particle oxidize CH4, and then they are restored to their original state by receiving oxygen from the Al3+ and Mg2+ ions in the support. The oxygen vacancies in the lattice due to the Cu2+ could easily induce oxygen delivery, and the reversible oxygen loss recovery by re-oxidation in the air reactor could be achieved. This is the most important factor in increasing oxygen transfer capacity. Ultimately, in this study, oxygen defects in the crystal lattices induced during the reaction seem to have a positive effect on the CH4 combustion reaction.

    更新日期:2019-12-11
  • Design and bio-applications of biological metal-organic frameworks
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Baoting Sun, Muhammad Bilal, Shiru Jia, Yunhong Jiang, Jiandong Cui

    Biological metal-organic frameworks (bioMOFs) are a new subclass of the MOF family. In comparison with traditional MOFs, the bioMOFs are made of multifunctional biologically related ligands (bio-ligand) and metal ions. The bio-ligands confer biological compatibility for traditional MOFs, thus providing many opportunities for a wide array of biological applications. This review highlights the recent advances in the synthesis of bioMOFs comprising multifunctional bio-ligands and metal ions. These bio-ligands include nucleobases, amino acids, peptides, proteins, cyclodextrin, saccharides, and other biomolecules. Furthermore, the potential bio-applications of bioMOFs in several fields such as biomedicine, biosensing and bioimaging, antimicrobial applications, biomimetic catalysis, chiral separation, and environmental protection are also demonstrated.

    更新日期:2019-12-11
  • Hydrodynamic modeling of the spiral-wound membrane module including the membrane curvature: reverse osmosis case study
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Morteza Taherinejad, Mahdi Moghimi, Shahram Derakhshan

    This study presents an integrated analytical model for the hydrodynamic behavior of the spiral-wound membrane element considering the curvature of the flow feed and permeate channels. The new model introduces a set of closed-form expressions for the output parameters of the permeate flow rate, fluid recovery fraction, and the permeation flux, which can be a necessary tool for optimization and evaluation of the parameters involved in the problem. Accordingly, the results were set forth for a reverse osmosis water treatment SWM element. The difference in the output parameters for the solutions with flat and curved membranes was investigated, and the consequences of the common assumption of the flat-sheet membrane were examined mathematically. It was found that neglecting the membrane curvature implements a significant impact/error on the prediction of the permeate channel pressure and membrane width with maximum permeation rate, whereas its impacts on feed channel pressure and output parameters are insignificant, especially for the considered reverse osmosis case study. Also, the curvature effect on the solution can be magnified by three parameters of the membrane width: permeate channel permeability, and membrane resistance.

    更新日期:2019-12-11
  • Poly(phenylene sulfide)-graphite composites for bipolar plates with preferred morphological orientation
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Ho-Joon Park, Jong Seok Woo, Soo-Young Park

    Bipolar plates in phosphoric acid fuel cells require inertness to phosphoric acid as well as excellent electrical, thermal, and mechanical properties. For this application, we prepared poly(phenylene sulfide) (PPS)-graphite composites with random or ordered graphite orientations by compression and extrusion-compression processes, respectively. Due to current limitations of extruding graphite-filled polymers, only moderately high graphite concentrations were used (up to 40 wt%). The compressed composites contained graphite sheets in a planar orientation (parallel to the pressing direction) and exhibited highly anisotropic electrical and thermal conductivity, with much higher in-plane than through-plane components. In contrast, composites that were extruded prior to compression exhibited randomly oriented graphite due to shearing forces during extrusion and therefore displayed isotropic properties. Thus, their through-plane electrical and thermal conductivity was superior to those of the ordered composite, while the in-plane properties were inferior. Notably, the internal graphitic structure affected the electrical conductivity more than the thermal conductivity. The randomly oriented composite also exhibited superior flexural strength, although the thermal stability of the two composites was almost equal. This study offers insights into the structure-property relationship of PPS-graphite composites as well as the effect of the orientation of conductive two-dimensional fillers on anisotropic properties.

    更新日期:2019-12-11
  • Evaluation of novel Mg/Al/Ni-BaFe ternary layered hydroxides uptake of methyl orange dye from water
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Nuhu Dalhat Mu’azu, Nabeel Jarrah, Mukarram Zubair, Mohammad Saood Manzar, Taye Saheed Kazeem, Mamdouh Al-Harthi

    MgAlNi-BaFe ternary layered hydroxide (UMLDH) and its calcined (CMLDH) form were synthesized and tested as adsorbents for methyl orange dye (MO) uptake from water. The adsorptive performances of the new magnetic nanocomposites were modeled, evaluated and optimized via response surface methodology (RSM). The UMLDH and CMLDH maximum removal efficiency and adsorption capacities data were fitted into RSM models with insignificant lack of fit (p-values<0.05) and high R2=0.991–0.997. The UMLDH and CMLDH MO adsorption capacities increased with decrease in both pH and initial MO concentration and decreased when the temperature was increased. Under optimal operating conditions, pseudo-second-order described kinetics of MO sorption on the nanocomposites, while the Freundlich isotherm gave the best fits for both the two adsorbents. The MO uptake simultaneously incorporated both mono and multi-layer surface adsorption involving strong electrostatic attraction and chemical interactions between MO and the adsorbents surface functional groups. Respectively, the obtained maximum Langmuir theoretical sorption capacity of 715.44 and 708 mg/g, indicated profoundly improved MO sorption capacities compared with many other magnetic-LDHs. These results demonstrate the potential of MgAlNi-BaFe as excellent adsorbents for effective remediation of dyes wastewater effluents.

    更新日期:2019-12-11
  • Antibacterial dynamic membranes loaded by cephalexin/amine-functionalized SBA_15 for Pb(II) ions removal
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Maryam Darzipour, Mohsen Jahanshahi, Majid Peyravi, Soodabeh Khalili

    Novel antibacterial dynamic membranes loaded by cephalexin/amine fiinctionalized SBA_15 were fabricated for heavy metal removal from aqueous solution. The mesoporous CPX/NH2-SBA_15 nanocomposite was formed as a uniform adsorptive and hydrophilic layer on the ultrafiltration polymeric membrane (PVDF). The modified adsorbent and membranes were characterized by SEM, XRD, N2 adsorption-desorption analysis, FT-IR, TGA, DSC and contact angle. A number of qualitative (well diffusion, disk diffusion) antibacterial assays were conducted against grampositive S. aureus and gram-negative E. coli. In addition, to evaluate its anti-biofouling performance, the model concentrated bacteria suspension in liquid medium was used as a feed solution. 100% bacteria mortality for certain concentration and suitable inhibition zones up to 3.5 cm were attained. An increment in the flux recovery from 55% (for UF) to 87% (for self-forming dynamic membrane (DM)) and 91% (for pre-coated DM) indicated that the dynamic layer improved the anti-biofouling property of the support membrane. High Pb(II) removal efficiency (99.8%) was achieved for the modified membrane during dynamic filtration test. CPX/NH2/SBA-15 dynamic membrane showed higher Pb2+ rejection than SBA-15 dynamic membrane because of amine groups located on the adsorbent surface. In general, membranes provide good performance like better flux and rejection besides antibacterial and anti-biofouling behavior.

    更新日期:2019-12-11
  • Enhanced proton conductivity of sulfonated poly(ether ether ketone) membranes at elevated temperature by incorporating (3-aminopropyl)triethoxysilane-grafted graphene oxide
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Shuguo Qu, Chenchen Zhang, Minhui Li, Yan Zhang, Lunbo Chen, Yushuai Yang, Bo Kang, Yiwei Wang, Jihai Duan, Weiwen Wang

    Making inexpensive proton exchange membrane with high proton conductivity for the proton exchange membrane fuel cell (PEMFC) is still a challenging problem. Graphene oxide (GO) nanoparticles grafted with (3-amino-propyl) triethoxy silane (APTES) were prepared and then incorporated into sulfonated poly(ether ether ketone) (SPEEK) matrix by solution casting to make the composite proton exchange membrane. The obtained nanoparticles and composite membranes were characterized by XRD, FT-IR, Raman, TGA, SEM, and UTM. GO treated with the silane coupling agent improved the dispersion stability and compatibility of GO in SPEEK, which decreased the agglomeration of GO nanoparticles in the SPEEK membrane. The prepared nanocomposite membranes exhibited better water retention properties and proton conductivity. The proton conductivity of the SPEEK membrane with 2 wt% amine functionalized GO (AGO) reached 11.32 mS/cm at 120 °C, which was 2.45-times higher than that of the pristine SPEEK membrane. The reason was that AGO nanoparticles disperse uniformly in the SPEEK membranes, which provides new channels for proton transfer. The potential application of this composite membrane in the PEMFC was indicated.

    更新日期:2019-12-11
  • A combined experimental and theoretical investigation of the adsorption of 4-Nitrophenol on activated biocarbon using DFT method
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Aola Supong, Parimal Chandra Bhomick, Upasana Bora Sinha, Dipak Sinha

    Porous activated biocarbon from Ravenna grass was utilized as an adsorbent for the removal of 4-Nitrophenol from aqueous solution. Chemical activation process using potassium hydroxide was adopted for the activated biocarbon preparation. The essential features of the prepared adsorbent represented by BET surface area, pore volume and pHZPC were 919 m2g−1, 0.324 cm3g−1 and 8.1 respectively. SEM, FTIR, XRD and TGA analysis revealed the microcrystallite and porous structure of the synthesized biocarbon with abundant functional groups and high thermal stability. Batch adsorption tests were conducted for 4-Nitrophenol adsorption, and the optimum adsorbent dose, pH, initial 4-Nitrophenol concentration and contact time were found to be 0.5 g, 7, 400 mgL−1 and 40 minutes, respectively. The equilibrium isotherm study revealed the suitability of the Langmuir isotherm with a maximum adsorption capacity of 50.89 mg/g. The pseudo-second-order kinetic model well represented the adsorption kinetics data, while thermodynamics study indicated the spontaneity (ΔG<0) and endothermic nature (ΔH>0) of the adsorption of 4-Nitrophenol. Density functional theory (DFT) calculations performed at the B3LYP level indicated that the interaction of 4-Nitrophenol with pristine and functionalized activated biocarbon is favorable.

    更新日期:2019-12-11
  • A preferential CO 2 separation using binary phases membrane consisting of Pebax®1657 and [Omim][PF 6 ] ionic liquid
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Kamran Shahrezaei, Reza Abedini, Mostafa Lashkarbolooki, Ahmad Rahimpour

    Pebax®1657 and [Omim][PF6] ionic liquid (IL) were used to fabricate a blend membrane and applied for CO2 separation. The changes upon adding ionic liquid into the polymer matrix as well as the membrane characteristics were studied through SEM, FTIR, DSC and TGA analysis. The obtained gas permeation results indicated that the CO2 permeability in all membranes was much higher than the other studied gases. CO2 permeability of Pebax containing 8 wt% IL increased from 82.3 Barrer up to 125.6 Barrer at a pressure of 2 bar, which showed a 53% increment compared to the neat Pebax membrane. Furthermore, as the [Omim][PF6] loading within the polymer matrix was increased, the CO2/CH4 and CO2/N2 selectivities improved. In addition, the permeability and selectivity of gases was enhanced as the feed pressure increased. Upon increasing feed pressure to 10 bar, the CO2 permeability of Pebax containing 8 wt% IL reached 185.3 Barrer, which was approximately 48% higher than the permeability at a pressure of 2 bar. Moreover, the selectivity of CO2/CH4 and CO2/N2 for the Pebax/8wt% IL membrane at pressure of 2 bar was 15.3 and 46.5, respectively, which improved to 19.7 and 59.8 as the pressure increased to 10 bar.

    更新日期:2019-12-11
  • Competency of chlorination roasting coupled water leaching process for potash recovery from K-feldspar: Mechanism and kinetics aspects
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Sandeep Kumar Jena, Nilima Dash, Akshaya Kumar Samal, Pramila Kumari Misra

    Potassium is an important mineral for biological functions. In this study, potassium was recovered from a low-grade potash mineral, feldspar through chlorination roasting followed by water leaching. NaCl and CaCl2 were used as additives for chlorination roasting independently The characterizations throughout the studies were carried out using a series of analytical and spectral techniques like XRD, SEM, FTIR, and Raman spectroscopy The effects of various experimental parameters such as particle size, roasting temperature, amounts of additives, and water leaching on potassium extraction were evaluated. Water leaching was found to be independent of leaching time, temperature, and agitator speed. During roasting, the formation of water-soluble phase was evident; this phase subsequently disappeared on water leaching. The potassium extraction kinetics in the presence of both the additives was satisfactorily corroborated by Ginstling-Brounshtein model. The activation energies for CaCl2 and NaCl roasting were calculated to be 90 and 122 kJ/mole, respectively. Under the same experimental conditions, 86% of potassium extraction (as potash value) was accomplished using CaCl2 as the additive, whereas the extraction in presence of NaCl was only up to 44%. The mechanism of potassium extraction was elucidated; the superior effectiveness of CaCl2 over NaCl in the extraction process was also explained.

    更新日期:2019-12-11
  • A modified non-equilibrium lattice fluid model based on corrected fractional free volume of polymers for gas solubility prediction
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Abolfazl Jomekian, Bahamin Bazooyar, Seyed Jalil Poormohammadian, Parviz Darvishi

    We propose a model based on non-equilibrium lattice fluid (NELF) theory and corrected fractional free volume of polymers to effectively and accurately predict the solubility of gases in different polymers. The method to achieve this purpose is based on the utilization of NELF model infinite dilution solubility coefficient (S0) as the base of predictive calculations. To account for the isolated pore in the polymer matrix in density estimation, a fractional free volume correction factor (β) was introduced in NELF model. The modified NELF model was successfully applied for prediction of solubility of C3H8 and CO2 in polyethylene oxide (PEO) and CO2 in polyethylene terephthalate (PET), isotactic polypropylene (i-PP), polyetherimide (PEI), polymethyl methacrylate (PMMA) and polyethyl methacrylate (PEMA) with adjustments in β value and depth of diffusion of gases in polymer matrix (ζ) at different pressures and temperatures. This work involves multi-objective optimization using genetic algorithm of MATLAB toolbox with adjusted settings. It applies to find the optimum temperature at which the minimum standard deviation of β for different gas-polymer systems is obtained. β showed the same trend of change with temperature as the constrained pressure imposed on the amorphous phase in semi-crystalline polymers. A cubic correlation for standard deviation for β versus temperature was obtained which was able to anticipate the changing trend of β at different temperatures. The chi-square test results verified that compared with original NELF model, a more accurate model for prediction of gas solubilities in polymers has been proposed.

    更新日期:2019-12-11
  • Removal of residual chloroform from amorphous paclitaxel pretreated by alcohol
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Hoe-Jong Kang, Jin-Hyun Kim

    A drying method that can effectively remove residual solvents from chloroform-induced amorphous paclitaxel was developed. Simple rotary evaporation with alcohol (methanol or ethanol) pretreatment was sufficient to remove residual chloroform and alcohol concentrations below the ICH limits (60 ppm for chloroform, 3,000 ppm for methanol, and 5,000 ppm for ethanol). In addition, SEM analysis and ultrasonic treatment showed that residual solvent removal is related to the porous structure of the sample due to the high vapor pressure of the chloroform-alcohol mixture and the hydrogen bonding between chloroform and alcohol.

    更新日期:2019-12-11
  • Effect of naphthalene quinoline and H 2 S on DBT hydrodesulfurization over unsupported NiMoW catalyst
    Korean J. Chem. Eng. (IF 2.476) Pub Date : 2019-12-04
    Changlong Yin, Haonan Zhang, Tongtong Wu, Zhuyan Wu, Kunpeng Li, Yan Kong, Chengwu Dong, Chenguang Liu

    Unsupported catalysts have attracted much attention for high activity in comparison with the traditional supported catalyst. Meanwhile, the clear structure of unsupported catalysts is helpful for the recognition of active phase for conducting the industry production. The NiMoW unsupported catalyst was prepared by hydrothermal synthesis and characterized by BET, XRD and HRTEM. The effects of naphthalene, quinoline and H2S on the hydrodesulfurization reactivity of dibenzothiophene (DBT) were investigated in both a batch autoclave and a continuous 10 ml fixed bed micro-reactor over NiMoW and supported catalyst for comparison. The results showed that the hydrogenation reaction and the hydrogenolysis reaction occurred on different active sites. For supported catalyst, the inhibition was relatively weaker, and the inhibition of the hydrodesulfurization pathway was much higher than the direct desulfurization pathway. Although unsupported catalyst was very sensitive to quinoline and H2S in this experiment, the HDS ratio on the unsupported catalyst was maintained at a high level above 99.7%, which is attributed to the very high active site density of unsupported catalysts.

    更新日期:2019-12-11
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