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Table of Content
28 March 2019, Volume 27 Issue 3
    Quadrature-based moment methods for the population balance equation: An algorithm review
    Dongyue Li, Zhipeng Li, Zhengming Gao
    2019, 27(3):  483-500.  doi:10.1016/j.cjche.2018.11.028
    Abstract ( 726 )   PDF (1306KB) ( 291 )  
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    The dispersed phase in multiphase flows can be modeled by the population balance model (PBM). A typical population balance equation (PBE) contains terms for spatial transport, loss/growth and breakage/coalescence source terms. The equation is therefore quite complex and difficult to solve analytically or numerically. The quadrature-based moment methods (QBMMs) are a class of methods that solve the PBE by converting the transport equation of the number density function (NDF) into moment transport equations. The unknown source terms are closed by numerical quadrature. Over the years, many QBMMs have been developed for different problems, such as the quadrature method of moments (QMOM), direct quadrature method of moments (DQMOM), extended quadrature method of moments (EQMOM), conditional quadrature method of moments (CQMOM), extended conditional quadrature method of moments (ECQMOM) and hyperbolic quadrature method of moments (HyQMOM). In this paper, we present a comprehensive algorithm review of these QBMMs. The mathematical equations for spatially homogeneous systems with first-order point processes and second-order point processes are derived in detail. The algorithms are further extended to the inhomogeneous system for multiphase flows, in which the computational fluid dynamics (CFD) can be coupled with the PBE. The physical limitations and the challenging numerical problems of these QBMMs are discussed. Possible solutions are also summarized.
    Fluid Dynamics and Transport Phenomena
    Influence of heat flux and Reynolds number on the entropy generation for different types of nanofluids in a hexagon microchannel heat sink
    A.A. Alfaryjat, A. Dobrovicescu, D. Stanciu
    2019, 27(3):  501-513.  doi:10.1016/j.cjche.2018.08.009
    Abstract ( 457 )   PDF (2251KB) ( 53 )  
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    Based on the Second Law of Thermodynamics, the entropy generation is studied for laminar forced convection flow of different nanoparticles (Al2O3, CuO and SiO2) mixed with water through a hexagon microchannel heat sink (HMCHS). The effects of different heat fluxes and Reynolds numbers on the entropy generation for different nanofluids, volume fractions and nanoparticles diameter are investigated. The heat flux is in the range of 125 to 500 kW·m-2 and the Reynolds numbers vary between 200 and 1500. The thermal, frictional and total entropy generations are calculated by integrating the volumetric rate components over the entire HMCHS. The results clearly show that the rise in the heat flux leads to an increase in the thermal entropy generation for nanofluids and pure water but they don't have any influence on the frictional entropy generation. Moreover, when the Reynolds number increases, the frictional entropy generation increases while the thermal entropy generation decreases. The results revealed that at low heat fluxes and high Reynolds numbers, pure water gives the lowest entropy generation, while at high heat flux the nanofluid has to be used in order to lower the overall irreversibility.
    Separation Science and Engineering
    Adsorption behaviors of avian immunoglobulins and purification of immunoglobulin Y from chicken serum with mixed-mode resins
    Yingdi Luo, Qilei Zhang, Shanjing Yao, Dongqiang Lin
    2019, 27(3):  514-518.  doi:10.1016/j.cjche.2018.05.011
    Abstract ( 346 )   PDF (1268KB) ( 55 )  
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    The importance of immunoglobulin Y (IgY) as a specific antibody equivalent to mammalian immunoglobulin G (IgG) is well recognized. However, production of highly purified IgY is still difficult due to the lack of specific purification methods. In this study, adsorption behaviors of IgY on four mixed-mode resins with functional ligands of 4-mercatoethyl-pyridine (MEP), 2-mercapto-1-methyli-midazole (MMI), 5-aminobenzi-midazole (ABI) and tryptophan-5-aminobenzi-midazole (W-ABI) were evaluated. The results showed that high adsorption ratio were found at pH 6.0-7.0 with little adsorption under acidic conditions. The resin with ABI ligand was then used to separate IgY from immunized chicken serum. An efficient process with IgY purity of 95% and recovery of 90% was developed after optimization of loading and elution pH and injection volume. The biological activity of the purified IgY was fully maintained. These results indicated that mixed-mode chromatography with specially-designed ligands has great potential for the separation of IgY from crude feedstock.
    Removal of Cd (Ⅱ) from dilute aqueous solutions by complexation–ultrafiltration using rotating disk membrane and the shear stability of PAA–Cd complex
    Liang Chen, Yunren Qiu
    2019, 27(3):  519-527.  doi:10.1016/j.cjche.2018.06.026
    Abstract ( 301 )   PDF (1547KB) ( 40 )  
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    Removal of cadmium (Ⅱ) ions from dilute aqueous solutions by complexation-ultrafiltration using rotating disk membrane was investigated. Polyacrylic acid sodium (PAAS) was used as complexation agent, as key factors of complexation, pH and the mass ratio of PAAS to Cd2+ (P/M) were studied, and the optimum complexation-ultrafiltration conditions were obtained. The effects of rotating speed (n) on the stability of PAA-Cd complex was studied with two kinds of rotating disk, disk I (without vane) and disk Ⅱ (with six rectangular vanes) at a certain range of rotating speed. Both of the rejection could reach 99.7% when n was lower than 2370 r·min-1 and 1320 r·min-1, for disk I and disk Ⅱ, respectively. However, when rotating speed exceeds a certain value, the critical rotating speed (nc), the rejection of Cd (Ⅱ) decreases greatly. The distribution of form of cadmium on the membrane was established by the membrane partition model, and the critical shear rate (γc), the smallest shear rate at which the PAA-Cd complex begins to dissociate, was calculated based on the membrane partition model and mass balance. The critical shear rates (γc) of PAA-Cd complex were 5.9×104 s-1, 1.01×105 s-1, and 1.31×105 s-1 at pH=5.0, 5.5, and 6.0, respectively. In addition, the regeneration of PAAS was achieved by shear induced dissociation and ultrafiltration.
    Removing ammonia from skim by air stripping with rotating packed bed
    Hongxing Gui, Xiuping Li
    2019, 27(3):  528-533.  doi:10.1016/j.cjche.2018.06.027
    Abstract ( 289 )   PDF (574KB) ( 63 )  
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    Based on the effects of skim components on ammonium removal as well as the current processing technology, a new process-intensified technology of removing ammonia from skim by air stripping on rotating packed bed was proposed. The experiments were conducted on a wave-thread packed Rotating Packed Bed (RPB) under atmospheric pressure, suggesting that, in terms of order of importance, the ammonium concentration of feed-stock (xw), the average ultra-gravity factor (β), feed-stock flux (L), and gas flux (G) had significant impact on ammonium removal rate (η) and the ammonium concentration of products (xD). In the experiment, mass-transfer coefficient in gas phase (kyae) increases with the increase of β, G/L, and L. The ammonium concentration of products decreases with the increase of β, G/L and the increase of L. The ammonium concentration of products would be as low as 0.10% and the ammonia removal rate would be 63.21% when skim temperature was 25℃, xw 0.28%, β 133.2, and G/L 15.0 m3·L-1. Experiment results indicated that the proposed technology for removing ammonium from skim on a rotating packed bed would be a new process-intensified technique compared with traditional aeration process and centrifugal atomization method.
    Mass transfer investigation and operational sensitivity analysis of aminebased industrial CO2 capture plant
    Abbas Hemmati, Hamed Rashidi
    2019, 27(3):  534-543.  doi:10.1016/j.cjche.2018.07.014
    Abstract ( 274 )   PDF (2455KB) ( 62 )  
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    In this article, the industrial process of CO2 capture using monoethanolamine as an aqueous solvent was probed carefully from the mass transfer viewpoint. The simulation of this process was done using Rate-Base model, based on two-film theory. The results were validated against real plant data. Compared to the operational unit, the error of calculating absorption percentage and CO2 loading was estimated around 2%. The liquid temperature profiles calculated by the model agree well with the real temperature along the absorption tower, emphasizing the accuracy of this model. Operational sensitivity analysis of absorption tower was also done with the aim of determining sensitive parameters for the optimized design of absorption tower and optimized operational conditions. Hence, the sensitivity analysis was done for the flow rate of gas, the flow rate of solvent, flue gas temperature, inlet solvent temperature, CO2 concentration in the flue gas, loading of inlet solvent, and MEA concentration in the solvent. CO2 absorption percentage, the profile of loading, liquid temperature profile and finally profile of CO2 mole fraction in gas phase along the absorption tower were studied. To elaborate mass transfer phenomena, enhancement factor, interfacial area, molar flux and liquid hold up were probed. The results show that regarding the CO2 absorption, the most important parameter was the gas flow rate. Comparing liquid temperature profiles showed that the most important parameter affecting the temperature of the rich solvent was MEA concentration.
    Catalysis, Kinetics and Reaction Engineering
    A high H2 evolution rate under visible light of a CdS/TiO2@NiS catalyst due to a directional electron transfer between the phases
    Jianling Meng, Yongdan Li
    2019, 27(3):  544-548.  doi:10.1016/j.cjche.2018.04.023
    Abstract ( 271 )   PDF (4226KB) ( 24 )  
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    The photocatalytic activity of CdS can be greatly improved by co-modification of NiS and TiO2 materials; furthermore the order of connection affects much. A directional electron transfer route via CdS → TiO2 → NiS is found crucial to the enhancement of ternary catalyst, where TiO2 acts as an electron reservoir and NiS works as an effective cocatalyst. CdS/TiO2@NiS with NiS loaded on TiO2 has an activity of H2 evolution 2.5 times higher than NiS@CdS/TiO2 with NiS pre-loaded on CdS. Faster e-/h+ separation rates is obtained of CdS/TiO2@NiS under visible light than under extra UV light irradiation, which in turn demonstrates the importance of directional electron transfer route.
    Non-phosgene synthesis of hexamethylene-1,6-diisocyanate from thermal decomposition of hexamethylene-1,6-dicarbamate over Zn–Co bimetallic supported ZSM-5 catalyst
    Yan Cao, Yafang Chi, Ammar Muhammad, Peng He, liguo Wang, Huiquan Li
    2019, 27(3):  549-555.  doi:10.1016/j.cjche.2018.05.001
    Abstract ( 388 )   PDF (1046KB) ( 77 )  
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    A non-phosgene route for the synthesis of hexamethylene-1,6-diisocyanate (HDI) was developed via catalytic decomposition of hexamethylene-1,6-dicarbamate (HDC) over Zn-Co bi-metallic supported ZSM-5 catalyst. The catalyst was characterized by FTIR and XRD analyses. Three solvents dioctyl sebacate (DOS), dibutyl sebacate (DBS) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) were investigated and compared; DOS gave better performance. The catalytic performances for thermal decomposition of HDC to HDI using DOS as solvent were then investigated, and the results showed that, under the optimized reaction conditions, i.e.,10 wt% concentration of HDC in DOS, 250℃ temperature, 60 min reaction time, 83.8% yield of HDI had been achieved over Zn-Co/ZSM-5. Decomposition of the intermediate hexamethylene-1-carbamate-6-isocyanate (HMI) over Zn-Co/ZSM-5 in DOS solvent was further studied and the results indicated that yield of HDI from HMI reached to 69.6% (98.6% HDI selectively) at 270℃, which further increased the yield of the total HDI (HDItol) to as high as 95.0%. Recycling of catalyst showed that HDI and HMI yield slightly decreased, and by-product yield increased after the catalyst was reused for 4 times. At last possible reaction mechanism was proposed.
    Cobalt Schiff base complexes: Synthesis characterization and catalytic application in Suzuki–Miyaura reaction
    Rasheeda M. Ansari, Lolakshi K. Mahesh, Badekai Ramachandra Bhat
    2019, 27(3):  556-563.  doi:10.1016/j.cjche.2018.05.002
    Abstract ( 347 )   PDF (1635KB) ( 69 )  
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    3-Methoxysalicylaldehyde was condensed with the amines 4-aminoacetophenone and 2-amino-5-bromopyridine to obtain Schiff base ligands, 1 and 2, which were coordinated to cobalt salts as complex 1 and complex 2, respectively. The synthesized ligands and complexes were characterized by spectroscopic (FT-IR, UV-Vis, 1H-NMR and mass spectrometry), thermal (TGA) and elemental analysis. The structures of the complexes were verified by evaluating their magnetic susceptibility and spectroscopic evidences. Synthesized complexes were studied for their catalytic activity in the Suzuki-Miyaura cross-coupling of aryl halides with phenylboronic acid. Optimized reaction yields 90% of the cyanobiphenyl for complex 1 and 91% for complex 2 with 0.1 mmol of catalyst loading thereby substantiating the C\\C coupling efficiency of the synthesized complexes, 1 and 2.
    Baeyer–Villiger oxidation of cyclohexanone catalyzed by cordierite honeycomb washcoated with Mg–Sn–W composite oxides
    Yang Han, Shengnan Li, Rong Ding, Wenjin Xu, Guangxu Zhang
    2019, 27(3):  564-574.  doi:10.1016/j.cjche.2018.05.007
    Abstract ( 275 )   PDF (5951KB) ( 34 )  
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    In this work, a series of Mg-Sn-W oxide powder catalysts with different tungsten oxide contents (0, 15 wt% and 30 wt%) were prepared and washcoated on cordierite honeycomb monoliths to produce monolithic catalysts, which were tested for the Baeyer-Villiger oxidation of cyclohexanone. The obtained monolithic catalysts, which combined the advantages of both homogeneous and heterogeneous catalysts, showed high catalytic efficiency and overcame the problems of product separation that occurred in the homogeneous catalytic process. SEM and EDX tests showed that the catalytic coating, with a thickness of approximately 20 μm, was compact and homogeneous, and an enlarged BET surface area was indicated by N2 adsorption-desorption compared with the bare cordierite honeycomb. The chemical properties on the catalytic surface of the powder and monolithic catalysts were characterized by XPS, which indicated the tin and tungsten on the catalysts exhibited their full oxide states and presented mainly as stannate and tungstate, as confirmed by XRD and FTIR characterizations. Moreover, the catalytic activity test indicated that the tungsten content of the catalysts played an important role in catalytic efficiency and that monolithic catalysts were produced without obvious catalytic activity loss compared with the corresponding powders. (M)W30, which exhibited excellent mechanical stability and maintained high activity after recycling three times, was the optimal catalyst, showing a high selectivity that exceeded 86% and a conversion above 64%. Therefore, the structured Mg-Sn-W oxide catalysts have great potential for application in practical production.
    Process Systems Engineering and Process Safety
    Effects of mechanical activation on the digestion of ilmenite in dilute H2SO4
    Xiaomei Wang, Chun Li, Hairong Yue, Shaojun Yuan, Changjun Liu, Siyang Tang, Bin Liang
    2019, 27(3):  575-586.  doi:10.1016/j.cjche.2018.06.020
    Abstract ( 317 )   PDF (7723KB) ( 25 )  
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    The commercial sulfate process for pigment production uses concentrated sulfuric acid (>85 wt% H2SO4) as feeding material and discharges 8-10 tons of spend dilute acid (20 wt% H2SO4) per ton of product. Re-using spend acid to leach ilmenite can cut the waste emission and save fresh feeding acid. However, the leaching reaction with dilute acid is very slow and the digestion efficiency is fairly low. This paper describes a wet-milling process to enhance the dilute-acid leaching of ilmenite that makes it possible to produce TiO2 pigment in a more environmentally benign routine. The leaching kinetic study of unmilled ilmenite, dry milled 60 min ilmenite and wet milled 60 min ilmenite was conducted by revision of the shrinking core model (SCM), incorporation of particle size distribution (PSD) into SCM. The results revealed that mechano-chemical activation method significantly increased the leaching efficiency of titanium from 36% to 76% by reducing the particle size and increasing the reaction contact area. On the other hand, the milling process increased the lattice deformation and amorphization of crystalline, which lowered the activation energies in the leaching process. Compared with dry milling operation, wet milling is more effective, the particle size distribution of wet-milled ilmenite was much narrower, smaller, and more uniform. Wet milling of ilmenite makes the leaching reaction with dilute acid (60 wt% H2SO4) practicable and the re-use of spend acid becomes possible and economical.
    Synthesis of the fluid machinery network in a circulating water system
    Wei Gao, Xiao Feng
    2019, 27(3):  587-597.  doi:10.1016/j.cjche.2018.06.030
    Abstract ( 326 )   PDF (6410KB) ( 58 )  
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    Energy consumption of the fluid machinery network in a circulating water system takes up a large part of energy consumption in the process industry, so optimization on the network will enhance the economic and environmental performance of the industry. In this paper, a synthesis approach is proposed to obtain the optimal network structure. The effective height curves are used as tools to perform energy analysis, so that the potential placement of water turbines and auxiliary pumps can be determined with energy benefit. Then economic optimization is carried out, by the mathematical model with the total cost as the objective function, to identify the branches for water turbines and auxiliary pumps with economic benefit. In this way, the optimal fluid machinery network structure can be obtained. The results of case study indicate that the proposed synthesis approach to optimize the fluid machinery network will obtain more remarkable benefits on economy, compared to optimizing only the water turbine network or pump network. The results under different flowrates of circulating water reveal that using a water turbine to recover power or adding an auxiliary pump to save energy in branches are only suitable to the flowrate in a certain range.
    Fault diagnosis for distillation process based on CNN–DAE
    Chuankun Li, Dongfeng Zhao, Shanjun Mu, Weihua Zhang, Ning Shi, Lening Li
    2019, 27(3):  598-604.  doi:10.1016/j.cjche.2018.12.021
    Abstract ( 466 )   PDF (813KB) ( 60 )  
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    Distillation is the most widely used operation for liquid mixture separation in the chemical industry. It is of great importance to detect and diagnose faults in distillation process. Due to the strong feedback and coupling of processes in a distillation column, it is difficult to use deep auto-encoders (DAEs) alone to achieve good results in detecting and diagnosing faults, in terms of accuracy and efficiency. This paper proposes a hybrid fault-diagnosis model based on convolutional neural networks (CNNs) and DAEs, by integrating the powerful capability of CNN in feature extraction and of DAE in classification. A case study was carried out with the distillation process of depropanization. It is shown that the proposed hybrid model is of good performance compared to other models, in terms of the accuracy of fault detection in such a process. Also, with the increase of structural layers of the CNN-DAE model, the diagnostic accuracy will be improved, with an optimal accuracy of 92.2%.
    Chemical Engineering Thermodynamics
    A new kinetic model for the common juniper essenstial oil extraction by microwave hydrodistillation
    Miljana S. Marković, Svetomir Ž. Milojević, Nevenka M. Bošković-Vragolović, Vladimir P. Pavićević, Ljiljana М. Babincev, Vlada B. Veljković
    2019, 27(3):  605-612.  doi:10.1016/j.cjche.2018.06.022
    Abstract ( 358 )   PDF (671KB) ( 62 )  
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    The main objective of the present study was to model the kinetics of essential oil extraction from swelled ground juniper berries by classic hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD). A new phenomenological kinetic model was developed on the basis of the juniper essential oil extraction mechanism that assumed three mass transfer processes occurring simultaneously:washing, unhindered diffusion and hindered diffusion. The new model was compared to the existing kinetic models. Among the tested models, the new model had the smallest mean relative percentage deviation and the highest corrected Akaike information criterion value. In addition, that, the new model was verified for HD and MAHD of essential oils from some other plant materials. On the basis of the above-mentioned facts, the new model can be recommended for modeling the kinetics of essential oil extraction by both HD and MAHD.
    Heat transfer model of two-phase flow across tube bundle in submerged combustion vaporizer
    Jiajun Song, Dongyan Han, Qinqin Xu, Dan Zhou, Jianzhong Yin
    2019, 27(3):  613-619.  doi:10.1016/j.cjche.2018.06.032
    Abstract ( 312 )   PDF (3017KB) ( 206 )  
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    In order to optimize the design of the submerged combustion vaporizer (SCV), an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV. Several experiments were conducted using water and CO2 as the heat transfer media in the tubes, respectively. The results indicated that hot air flux, the initial liquid level height and the tube pitch ratio had great influence on the heat transfer coefficient outside the tube bundle (ho). Finally, the air flux associated factor β and height associated factor γ were introduced to propose a new ho correlation. After verified by experiments using cold water, high pressure CO2 and liquid N2 as heat transfer media, respectively, it was found that the biggest deviation between the predicted and the experimental values was less than 25%.
    Estimating solubility of supercritical H2S in ionic liquids through a hybrid LSSVM chemical structure model
    Alireza Baghban, Jafar Sasanipour, Sajjad Habibzadeh, Zhi'en Zhang
    2019, 27(3):  620-627.  doi:10.1016/j.cjche.2018.08.026
    Abstract ( 281 )   PDF (2749KB) ( 85 )  
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    Development of a predictive tool for H2S solubility estimation can be very helpful in gas sweetening industry. Experimental databases on H2S solubility were rarely available, so as reliable predictive models. Thus, in this study the H2S solubility database was established, and then a Least-Squares Support Vector Machine (LSSVM) approach based on the established database is proposed. Group contribution method was also applied to eliminate the model's dependence on experimental data. Accordingly, our proposed LSSVM model can predict H2S solubility as a function of temperature, pressure, and 15 different chemical structures of Ionic liquids (ILs). Root Mean Square Error (RMSE) and coefficient of determination (R2) are 0.0122 and 0.9941, respectively. Moreover, comparison of our model with other existing models showed its reliability for H2S solubility in ILs. This can be very useful for engineers dealing with gas sweetening process in different applications of analysis, simulation, and designation.
    Heat of absorption of CO2 in aqueous N,N-diethylethanolamine+ N-methyl-1,3-propanediamine solutions at 313 K
    Katarzyna Sobala, Hanna Kierzkowska-Pawlak
    2019, 27(3):  628-633.  doi:10.1016/j.cjche.2018.11.027
    Abstract ( 298 )   PDF (620KB) ( 25 )  
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    Differential heat of absorption of CO2 in aqueous solutions of N,N-diethylethanolamine (DEEA) and activated DEEA solutions up to a total concentration of 2 mol·L-1 was measured as a function of CO2 loading at 313.15 K using a reaction calorimeter. In order to analyze the performance of N-methyl-1,3-propanediamine (MAPA) as an activator, DEEA blended solutions containing 0.05, 0.1 and 0.2 mol·L-1 MAPA were studied. The heat of CO2 absorption in single DEEA solutions was unaffected by changing the DEEA concentration in the range of (0.5-2) mol·L-1. On the other hand, increasing the concentration of MAPA in aqueous amine mixtures of (DEEA + MAPA) raised the heat of absorption.
    Biotechnology and Bioengineering
    Characterization of recuperating talent of white-rot fungi cells to dye-contaminated soil/water
    Bugra Dayi, Aidai Duishemambet Kyzy, Hatice Ardag Akdogan
    2019, 27(3):  634-638.  doi:10.1016/j.cjche.2018.05.004
    Abstract ( 238 )   PDF (521KB) ( 70 )  
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    This study was purposed to explore the decolorization of dyes by fungi on either a soil or in a liquid medium and to determine the application through batch shaking system. Two commercial dyes were decolorized and studied with four fungal strains in three media. Fungal growth is the best in malt extract/glucose medium for all organisms. Decolorization of reactive blue 220 and methyl red was investigated in soil medium by Trametes versicolor. These dyes were removed 91% and 80% for methyl red and reactive blue 220 respectively (dye concentration; 100 mg·L-1) by both organisms. Enzymatic activities were monitored. Laccase (Lac) and manganese peroxidase (MnP) were detected. MnP enzyme had important role for the dye decolorization. This study demonstrates that it is possible to decolorize some synthetic dyes, which would be highly advanced for dye containing wastewater and soil. These applications could be used for dye bioremediation.
    Enhanced removal of nitrate and phosphate from wastewater by Chlorella vulgaris: Multi-objective optimization and CFD simulation
    Mohammad Bagher Sabeti, Mohammad Amin Hejazi, Afzal Karimi
    2019, 27(3):  639-648.  doi:10.1016/j.cjche.2018.05.010
    Abstract ( 669 )   PDF (5038KB) ( 118 )  
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    To enhance the efficiency of wastewater biotreatment with microalgae, the effects of physical parameters need to be investigated and optimized. In this regard, the individual and interactive effects of temperature, pH and aeration rate on the performance of biological removal of nitrate and phosphate by Chlorella vulgaris were studied by response surface methodology (RSM). Furthermore, a multi-objective optimization technique was applied to the response equations to simultaneously find optimal combinations of input parameters capable of removing the highest possible amount of nitrate and phosphate. The optimal calculated values were temperature of 26.3℃, pH of 8 and aeration rate of 4.7 L·min-1. Interestingly, under the optimum condition, approximately 85% of total nitrate and 77% of whole phosphate were removed after 48 h and 24 h, respectively, which were in excellent agreement with the predicted values. Finally, the effect of baffle on mixing performance and, as a result, on bioremoval efficiency was investigated in Stirred Tank Photobioreactor (STP) by means of Computational Fluid Dynamics (CFD). Flow behavior indicated substantial enhancement in mixing performance when the baffle was inserted into the tank. Obtained simulation results were validated experimentally. Under the optimum condition, due to proper mixing in baffled STP, nitrate and phosphate removal increased up to 93% and 86%, respectively, compared to unbaffled one.
    Experimental study and simulation of a three-phase flow stirred bioreactor
    Chenghui Zheng, Jiashun Guo, Chengkai Wang, Yuanfeng Chen, Huidong Zheng, Zuoyi Yan, Qinggen Chen
    2019, 27(3):  649-659.  doi:10.1016/j.cjche.2018.06.010
    Abstract ( 247 )   PDF (5719KB) ( 36 )  
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    In order to obtain the reasonable operating conditions and minimize the power consumption in the stirred bioreactor, the hydrodynamic experiments in the stirred bioreactor have been taken to obtain the basic data. Subsequently, an Eulerian model for the gas-liquid-solid three phase flow in the stirred bioreactor has been proposed and the CFD simulation has been conducted. By comparing the results of experiment and simulation, it can be concluded that the simulation results were consistent with the experimental data. The inner relationship between operating variables and indicators could be obtained by comparing the results of just suspension speed, gas holdup, power consumption and operational maps, further the reasonable operating conditions could be also determined under the minimum power consumption. The operational maps could provide the theoretical foundation for industrial application of the gas-liquid-solid stirred bioreactors under the low solid concentration (no more than 20 wt%).
    Energy, Resources and Environmental Technology
    An ultrasonic-ionic liquid process for the efficient acid catalyzed hydrolysis of feather keratin
    Song Ding, Yang Sun, Hongyue Chen, Chao Xu, Yi Hu
    2019, 27(3):  660-667.  doi:10.1016/j.cjche.2018.05.008
    Abstract ( 357 )   PDF (2726KB) ( 57 )  
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    A novel efficient method for hydrolyzing feather keratin using an ultrasonic-ionic liquid coupling process has been developed, with reaction conditions optimized using response surface analysis of data obtained from single factor optimization studies. Ultrasonic irradiation (225 W power) of feathers in 8.4 mol·L-1 hydrochloric acid containing 1-butyl-3-methylimidazolium chloride as a cosolvent at 80℃ for 1.4 h, followed by heating at 110℃ for 8.3 h, resulted in hydrolysis of their keratin component in an excellent 83.1% yield. Compared with previous methods, this new method employs reduced amounts of hydrochloric acid, shorter reaction time, and affords amino acid hydrolysis products in higher yield.
    Nucleation of methane hydrate and ice in emulsions of water in crude oils and decane under non-isothermal conditions
    Andrey S. Stoporev, Lidiya I. Svarovskaya, Larisa A. Strelets, Lubov' K. Altunina, Galina V. Villevald, Tamara D. Karpova, Tatyana V. Rodionova, Andrey Yu. Manakov
    2019, 27(3):  668-676.  doi:10.1016/j.cjche.2018.09.003
    Abstract ( 251 )   PDF (1335KB) ( 26 )  
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    Achievable supercooling for the formation of methane hydrate from water emulsions was studied in seven different crude oils and in decane. The experiments were performed under constant rate cooling from +20 to -15℃ and a pressure of methane of 12 MPa. It was demonstrated that the shapes and positions of the resulting survival curves depend on the density, viscosity and dispersive power of oil samples used in the experiments, as well as on the degree of oil oxidation. In addition, results of the experiments on ice freezing under the same emulsions are presented. The results obtained in the work allowed us to discuss the possibility and features of primary and secondary nucleation of the hydrate and ice in the systems under consideration
    Ethanol steam reforming study over ZSM-5 supported cobalt versus nickel catalyst for renewable hydrogen generation
    Ashutosh Kumar, Ram Prasad, Yogesh Chandra Sharma
    2019, 27(3):  677-684.  doi:10.1016/j.cjche.2018.03.036
    Abstract ( 324 )   PDF (5452KB) ( 42 )  
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    The renewable hydrogen generation through ethanol steam reforming is one of the anticipated areas for sustainable hydrogen generation. To elucidate the role of Ni and Co with ZSM-5 support, catalysts were prepared by wet impregnation method and ethanol steam reforming (ESR) was performed. The catalysts were characterized by HR-XRD, ATR-FTIR, HR-SEM, TEM with SAED, EDAX, surface area analyzer and TPR. It had shown complete ethanol conversion at 773 K, but the selectivity in hydrogen generation was found higher for 10% Ni/ZSM-5 catalyst as compared to 10% Co/ZSM-5. The 10% Ni/ZSM-5 catalyst has about 72% hydrogen selectivity at temperature 873 K. It indicates that Ni is a more sustainable catalyst as compared to Co with ZSM-5 support for ESR. The C2H4 was found major undesirable products up to 823 K temperature. Nevertheless, the 10% Ni/ZSM-5 catalyst had shown its stability for high temperature (873 K) ESR performance.
    Materials and Product Engineering
    TOPSIS based Taguchi design optimization for CVD growth of graphene using different carbon sources: Graphene thickness, defectiveness and homogeneity
    Barış Şimşek
    2019, 27(3):  685-694.  doi:10.1016/j.cjche.2018.08.004
    Abstract ( 220 )   PDF (4523KB) ( 45 )  
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    Chemical inhomogeneity of chemical vapor deposition (CVD) grown graphene compromises its usage in highperformance devices. In this study, TOPSIS based Taguchi optimization was performed to improve thickness uniformity and defect density of CVD grown graphene. 1.56% decrease in the mean 2D/G intensity ratio, 87.96% improvement in the mean D/G intensity ratio, 56.07% improvement in the standard deviation D/G intensity ratio, 25.21% improvement in the standard deviation 2D/G intensity ratio, and 69.32% improvement in the surface roughness were achieved with TOPSIS based Taguchi optimization. The statistical differences between the copper and silicon substrates have been found significantly in terms of their impacts on the graphene's properties with the 0.000 p-value for the mean D/G intensity ratio and with the 0.009 p-value for the mean 2D/G intensity ratio, respectively. Graphene having 11% lower mean D/G intensity ratio (low defective graphene products) compared to the values given in the literature using single-response optimization was obtained using multi-response optimization.
    Preparation and phase change performance of Na2HPO4·12H2O@poly (lactic acid) capsules for thermal energy storage
    Na Fan, Lang Chen, Guoyong Xie, Donghong Yin, Chak-Tong Au, Shuangfeng Yin
    2019, 27(3):  695-700.  doi:10.1016/j.cjche.2018.05.017
    Abstract ( 321 )   PDF (1496KB) ( 136 )  
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    Micro-encapsulated phase-change materials (microPCMs) with Na2HPO4·12H2O encapsulated in poly(lactic acid) (PLA) shell were prepared by a solvent evaporation-precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol (PVA) concentration on phase change properties were investigated. The thermal properties of microPCMs were characterized by differential scanning calorimetry (DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g-1.
    Investigation on the key aspects of l-arginine para nitrobenzoate monohydrate single crystal: A non-linear optical material
    Sonia, N. Vijayan, Mahak Vij, Kanika Thukral, Naghma Khan, D. Haranath, Rajnikant, M. S. Jayalakshmy
    2019, 27(3):  701-708.  doi:10.1016/j.cjche.2018.06.029
    Abstract ( 364 )   PDF (3421KB) ( 148 )  
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    In the contemporary days, non-linear optical materials (NLO) are getting higher attention as per the increasing demand in optical communication and data storage technology. Consequently, they explore various physical properties of the NLO material for their industrial applications. In current report, l-arginine p-nitrobenzoate monohydrate (LANB) single crystals were obtained by adopting slow cooling technique. The structural confirmation of grown single crystal was carried out using single crystal X-Ray diffractometer. Presence of strain within single crystal was deduced using Hall-Williamson relation. Various defects associated within single crystal were assessed using high resolution XRD. Additionally, its crystalline quality was again confirmed by time resolved photoluminescence spectroscopy (TRPL). Using transmission spectra, the cut off wavelength and band gap of the host material was determined to be nearly 420 nm and 2.9 eV respectively. The dielectric property has been recorded by varying the frequency ranging from 50 Hz to 100 kHz. The curve suggests that dielectric loss value is less at high frequency ensures the suitability of crystal in photonics and NLO based devices. The laser damage threshold values were also measured for single and multiple shots. Thermal parameters of the titled compound were calculated using PPE. In photoconductivity measurement, negative photoconductivity has been observed in titled compound. Microhardness studies were also performed on single crystal to explore its mechanical properties.
    Nitrogen-doped hierarchical porous carbon from polyaniline/silica self-aggregates for supercapacitor
    Peipei Li, Dazhi Zhang, Yunhui Xu, Caihua Ni, Gang Shi, Xinxin Sang
    2019, 27(3):  709-716.  doi:10.1016/j.cjche.2018.09.014
    Abstract ( 273 )   PDF (4614KB) ( 24 )  
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    In this paper, nitrogen-doped hierarchical porous carbon (N-HPC) was prepared from polyaniline (PANI)/silica self-aggregates. H-bonding between N\\H groups in aniline/PANI and\\OH groups in nano silica template led to a self-assembly type, which enabled the formation of uniform N-HPC nanoparticles. Silica self-aggregates provided macroporous channels resulted in a decreased diffusion distance. After removing the hard template, the N-HPC had a high surface area (899 m2·g-1). Owing to two co-existed synergetic energy-storage mechanisms and the hierarchical porous structure, the obtained N-HPC exhibited a high specific capacitance of 218.75 F·g-1 at 0.5 A·g-1, compared with the nonporous nitrogen-doped carbon (N-C) derived from pure PANI. Moreover, the N-HPC electrode demonstrated excellent cycle life, retaining 99% of its initial specific capacitance after 1000 cycles.
    Inhibition behavior of Tragia involucrata L. phenolic compounds against acidic medium corrosion in low carbon steel surface
    Ill-Min Chung, Seung-Hyun Kim, Venkatesan Hemapriya, Kathirvel Kalaiselvi, Mayakrishnan Prabakaran
    2019, 27(3):  717-725.  doi:10.1016/j.cjche.2018.10.008
    Abstract ( 325 )   PDF (7714KB) ( 18 )  
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    The antioxidant and anticorrosive effect of Tragia involucrate L. (T. involucrate L.) was evaluated to aid in finding new compounds which can be used for various purposes. The total phenolic (TPC) and flavonoid content (TFC), antioxidant activity (DPPH, reducing potential and phosphomolybdenum), and electrochemical measurements, Fourier transform infrared (FT-IR), UV-visible (UV-vis) spectral analysis, scanning electron microscopy/energydispersive X-ray spectroscopy (SEM-EDX) and atomic force microscopy (AFM) were done to analyze the potency and also the inhibition efficiency of T. involucrate L. against 1 mol·L-1 HCl on low carbon steel. The TPC (145.21 mg GAE·g-1), TFC (52.32 mg QCE·g-1) and antioxidant activities were found to be significant. The electrochemical studies performed by AC impedance measurements showed significant changes in impedance spectra without causing any change in Nyquist plots. An increase in charge transfer resistance (Rct) values, a blockage in active sites exhibiting cathodic and anodic inhibition shows the action of inhibitor on low carbon steel. This was later confirmed by FT-IR and UV-vis which showed variation in absorption band at 270 nm and 273 nm (before immersion) and 208 and 281 nm (after immersion). The same was tested again by SEM-EDX through altered strength of iron and oxygen bands and using AFM by analyzing the change in average roughness values of low carbon steel before (61.65 nm) and after (97.87 nm) exposure to blank acid without inhibitor, while it was shifted to 81.58 nm in acid with inhibitor. All these results showed strong evidence adding values to T. involucrate L. plant extract in inhibiting corrosion on low carbon steel and by promoting antioxidant importance of the extract which helps in scavenging free radicals.
    Modeling of thermal conductivity and density of alumina/silica in water hybrid nanocolloid by the application of Artificial Neural Networks
    Sathishkumar Kannaiyan, Chitra Boobalan, Fedal Castro Nagarajan, Srinivas Sivaraman
    2019, 27(3):  726-736.  doi:10.1016/j.cjche.2018.07.018
    Abstract ( 264 )   PDF (4107KB) ( 58 )  
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    In this research work, the thermal conductivity and density of alumina/silica (Al2O3/SiO2) in water hybrid nanofluids at different temperatures and volume concentrations have been modeled using the artificial neural networks (ANN). The nanocolloid involved in the study was synthesized by the two-step method and characterized by XRD, TEM, SEM-EDX and zeta potential analysis. The properties of the synthesized nanofluid were measured at various volume concentrations (0.05%, 0.1% and 0.2%) and temperatures (20 to 60℃). Established on the observational data and ANN, the optimum neural structure was suggested for predicting the thermal conductivity and density of the hybrid nanofluid as a function of temperature and solid volume concentrations. The results indicate that a neural network with 2 hidden layers and 10 neurons have the lowest error and a highest fitting coefficient of thermal conductivity, whereas in the case of density, the structure with 1 hidden layer consisting of 4 neurons proved to be the optimal structure.