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Table of Content
28 August 2019, Volume 27 Issue 8
    Fluid Dynamics and Transport Phenomena
    Numerical study of n-heptane/benzene separation by thermal diffusion column
    Neda Hashemipour, Javad Karimi-Sabet, Kazem Motahari, Saeed Mahruz Monfared, Younes Amini, Mohammad Ali Moosavian
    2019, 27(8):  1745-1755.  doi:10.1016/j.cjche.2018.10.004
    Abstract ( 252 )   PDF (5329KB) ( 114 )  
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    In this article, numerical simulations are performed to investigate the performance of the thermal diffusion column for the separation of n-heptane/benzene mixture. The present work tried to optimize column by analyzing significant parameters such as feed flow rate, temperature and cut. In order to obtain the hydrodynamic and temperature and mass distribution inside thermal diffusion column, computational fluid dynamic (CFD) method is applied to solve the Navier-Stocks equations. Numerical simulations are conducted to study the main parameters in both stationary and time-dependent conditions. By using the separation work unit as a function of cut, the optimal cut for maximum SWU occurs within a limited range of 0.47-0.5 for feed rate between 0.5 and 4·g min-1. Our findings reveal that the optimum feed rate in the range of optimum cut is about 1 g min-1. In transient study, results show that the best cut for reaching to steady-state condition is θ=0.5.
    Droplet characteristics in the multi-staged high speed disperser with single inlet
    Ao Nie, Ziqi Cai, Zhengming Gao, Zhimiao Wang, Archie Eaglesham
    2019, 27(8):  1756-1764.  doi:10.1016/j.cjche.2018.12.017
    Abstract ( 231 )   PDF (6840KB) ( 15 )  
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    Droplet characteristics in the cavity zone of a multi-staged high speed disperser with single inlet were studied in this paper. The influences of both the operating and structural parameters on the mean droplet diameter, size distribution and liquid flux distribution were quantitatively analyzed. The result showed that the mean droplet diameter decreased with the increase of rotational speed and the number of rotors; whilst there is little influence on the inlet flow rate. In the experimental range, the minimum value of mean droplet diameter is 0.57 mm, 0.48 mm, 0.41 mm in the two-staged, three-staged and four-staged rotors, respectively. The Rosin-Rammler (R-R) distribution could describe the droplet size distribution appropriately, and it became uniform with the increase of rotational speed and the number of rotor, while the inlet flow rate had little effect on the droplet size distribution. The liquid flux distribution curves were always unimodal. With the increase of rotational speed, the location of maximum liquid flux ratio moved from zone 3 to zone 4 and this value decreased from 22.1% to 18.1%. Using Coefficient of Variation (CV) to indicate the uniformity of liquid flux distribution, it was found that the CV decreases from 47.5% to 22.7% when the number of rotor increased from 2 to 4.
    Bubble coalescence efficiency near multi-orifice plate
    Jiming Wen, Qiunan Sun, Zhongning Sun, Haifeng Gu
    2019, 27(8):  1765-1776.  doi:10.1016/j.cjche.2018.11.006
    Abstract ( 195 )   PDF (9515KB) ( 15 )  
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    Bubble coalescence reduces specific area and weakens the work performance of bubble column. The bubble coalescence near gas sparger which is caused mainly by bubble growing is different from the ones occurring in major liquid. Bubble coalescence efficiency near gas sparger is influenced by many factors including sparger configuration, gas flow rate, bubble deformation, solution composition, etc. This work has conducted a set of visual experiments to study the coalescence characteristics near multi-orifice plate. The experiment parameters cover a wide range of conditions including large scope of gas flow rate, different kinds of solution and orifice configurations. The experimental results suggest that coalescence time is applicable to reflect the influence of the pitch of orifices and gas flow rate on bubble coalescence efficiency. As the number of orifices increases, bubble coalescence efficiency is reduced by the disturbance from the bubbles at adjacent orifices. A hindering coefficient is used to consider the hindering effect of additives on bubble coalescence efficiency. Finally a new calculation expression is established to predict bubble coalescence efficiency near multi-orifice plate whose fundamental form is based on the logistic curve of binary response. The calculated values that refer to this calculation expression are well consistent with the experimental results.
    Entransy dissipation analysis of interfacial convection enhancing gasliquid mass transfer process based on field synergy principle
    Dong Li, Aiwu Zeng
    2019, 27(8):  1777-1788.  doi:10.1016/j.cjche.2019.03.017
    Abstract ( 148 )   PDF (5721KB) ( 27 )  
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    An exploration of the gas CO2 absorbed into liquid ethanol accompanied with Rayleigh convection is performed by analyzing the mass entransy dissipation; this new statistical quantity is introduced to describe the irreversibility of mass transfer potential capacity. Based on the general advection-diffusion differential equation for an unsteady mass transfer process, the variation of the included angle between the velocity vector and concentration gradient fields is investigated to reveal the underlying mechanism of interfacial convection enhancing mass transfer. Results show some identical characteristics with the qualitative analyses of the synergy effects generated by the concentration and velocity fields after interfacial convection occurring for a boundary condition of fixed surface concentration. And the equivalent mass resistance for convective mass transfer process presents the similar variation with the reciprocal of instantaneous mass transfer coefficient. Accordingly, it is reasonable to be seen that mass transfer dissipation rate could be provided to assess the convection strength and explain fundamentally how Rayleigh convection improves mass transfer performance through establishing a close relationship between the mass transfer capacity and field synergy principle from the view of mass transfer theory.
    Separation Science and Engineering
    Performance evaluation of polyamide nanofiltration membranes for phosphorus removal process and their stability against strong acid/alkali solution
    Yen Khai Chai, How Chun Lam, Chai Hoon Koo, Woei Jye Lau, Soon Onn Lai, Ahmad Fauzi Ismail
    2019, 27(8):  1789-1797.  doi:10.1016/j.cjche.2018.09.029
    Abstract ( 202 )   PDF (4110KB) ( 71 )  
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    In this study, a quantitative performance of three commercial polyamide nanofiltration (NF) membranes (i.e., NF, NF90, and NF270) for phosphorus removal under different feed conditions was investigated. The experiments were conducted at different feed phosphorus concentrations (2.5, 5, 10, and 15 mg·L-1) and elevated pHs (pH 1.5, 5, 10, and 13.5) at a constant feed pressure of 1 MPa using a dead-end filtration cell. Membrane rejection against total phosphorus generally increased with increasing phosphorus concentration regardless of membrane type. In contrast, the permeate flux for all the membranes only decreased slightly with increasing phosphorus concentration. The results also showed that the phosphorus rejections improved while water flux remained almost unchanged with increasing feed solution pH. When the three membranes were exposed to strong pHs (pH 1.5 and 13.5) for a longer duration (up to 6 weeks), it was found that the rejection capability and water flux of the membranes remained very similar throughout the duration, except for NF membrane with marginal decrement in phosphorus rejection. Adsorption study also revealed that more phosphorus was adsorbed onto the membrane structure at alkaline conditions (pH 10 and 13.5) compared to the same membranes tested at lower pHs (pH 1.5 and 5). In conclusion, NF270 membrane outperformed NF and NF90 membranes owing to its desirable performance of water flux and phosphorus rejection particularly under strong alkali solution. The NF270 membrane achieved 14.0 L·m-2·h-1 and 96.5% rejection against 10 mg·L-1 phosphorus solution with a pH value of 13.5 at the applied pressure of 1 MPa.
    Fouling process and anti-fouling mechanisms of dynamic membrane assisted by photocatalytic oxidation under sub-critical fluxes
    Tao Yang, Fen Liu, Houfeng Xiong, Qiyong Yang, Fushan Chen, Changchao Zhan
    2019, 27(8):  1798-1806.  doi:10.1016/j.cjche.2018.10.019
    Abstract ( 211 )   PDF (5031KB) ( 56 )  
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    Membrane fouling is often considered as a hindrance for the application of microfiltration/ultrafiltration (MF/UF) for drinking water production. A novel process of photocatalytic membrane reactor/dynamic membrane (PMR/DM), operating in a continuous mode under sub-critical flux, was proposed for the mitigation of membrane fouling caused by humic acids (HAs) in water. The mechanism of membrane fouling alleviation with synergistic photocatalytic oxidation and dynamic layer isolating effect was comprehensively investigated from the characterization of foulant evolution responsible for the reversible and irreversible fouling. The results showed that the PMR/DM utilized photocatalytic oxidation to enhance the porosity and hydrophilicity of the fouling layer by converting the high molecular weight (MW) and hydrophobic HA molecules with carboxylic functional groups and aromatic structures into low-MW hydrophilic or transphilic fractions, including tryptophan-like or fulvic-like substances. The fouling layer formed in the PMR/DM by combination of photocatalytic oxidation and DM running at a sub-critical flux of 100 L·h-1·m-2, was more hydrophilic and more porous, resulting in the lowest trans-membrane pressure (TMP) growth rates, as compared to the processes of ceramic membrane (CM), DM and PMR/CM. Meanwhile, the dynamic layer prevented the foulants, particularly the high-MW hydrophobic fractions, from contacting the primary membrane, which enabled the membrane permeability to be restored easily.
    Support surface pore structures matter: Effects of support surface pore structures on the TFC gas separation membrane performance over a wide pressure range
    Mengqi Shi, Chenxi Dong, Zhi Wang, Xinxia Tian, Song Zhao, Jixiao Wang
    2019, 27(8):  1807-1816.  doi:10.1016/j.cjche.2018.12.009
    Abstract ( 186 )   PDF (10173KB) ( 17 )  
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    In this work, the effects of support surface pore structures (including surface pore size, surface pore density and surface porosity) on the performance of thin film composite (TFC) gas separation membrane over a wide pressure range (from 0.3 to 2.0 MPa) were studied. To fulfill it, the polysulfone (PSf) supports with different surface pore structures were prepared. Two kinds of wide-accepted polymeric membrane materials, i.e., polyvinylamine (PVAm) and Pebax 1657 copolymer, were used as skin layer materials. We pointed out for the first time that the support surface average pore size and pore density could affect the chain mobility of polymer of skin layer at the support surface pore entrance, then, can affect the TFC membrane performance. Besides, we also discussed the effects of support on the TFC membrane performance when the feed pressure changes for the first time. This work can provide guidance for choosing a suitable support for TFC gas separation membrane.
    Intensification of zirconium and hafnium separation through the hollow fiber renewal liquid membrane technique using synergistic mixture of TBP and Cyanex-272 as extractant
    A. Yadollahi, M. Torab-Mostaedi, K. Saberyan, A. Charkhi, F. Zahakifar
    2019, 27(8):  1817-1827.  doi:10.1016/j.cjche.2018.12.018
    Abstract ( 329 )   PDF (6210KB) ( 86 )  
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    The novel synergistic mixture of TBP and Cyanex-272 is used as the extractant in the hollow fiber renewal liquid membrane (HFRLM) technique for Zr/Hf separation. The effects of the chemical and operational parameters such as HNO3 concentration in the donor phase, NH4F concentration in the acceptor phase, Cyanex-272 and TBP concentration in the liquid membrane phase, the lumen and shell side flow rates, and aqueous/organic volume ratio on the mass transfer and separation performance of HFRLM method were investigated. The obtained results reveal the intensification potential of proposed HFRLM technique for selective extraction of Zr over Hf with separation factor higher than 100. The HFRLM method provides two times higher mass transfer flux in comparison with hollow fiber supported liquid membrane (HFSLM). Also, the HFRLM method shows satisfactory stability for 700 min of continuous operation. The Zr ion transport through the LM phase follows the coupled co-transport mechanism and the diffusion in the renewal layer is recognized as the rate-controlling step in the HFRLM process. Moreover, the Zr mass transfer coefficient and molar flux in the HFRLM method are calculated in the range of 1× 10-8 to 8.4× 10-7 m·s-1 and 4.9× 10-6 to 20.1 ×10-6 mol·m-2 s-1, respectively.
    Grouping separation of mixed rare earths from their coexisting aqueous solutions by liquid-column elution
    Wenjuan Cao, Kun Huang, Xiaoqin Wang, Huizhou Liu
    2019, 27(8):  1828-1836.  doi:10.1016/j.cjche.2019.01.009
    Abstract ( 231 )   PDF (4773KB) ( 46 )  
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    A new approach was proposed for grouping separation of 14 lanthanide rare-earth ions from their coexisting mixed aqueous solutions, by performing liquid-column elution using the aqueous solution containing 14 lanthanide rare-earth ions as the stationary phase and the dispersed organic oil droplets containing P507 extractant as the mobile phase. It was revealed that 14 lanthanide rare-earth ions could be separated into four groups, according to the lanthanide tetrad effect, respectively eluting out from the liquid column at different time in a certain order. Various effects including the saponification degree of P507, the concentration of P507 in organic phase, the length and inner diameter of the extraction column on the performance of grouping separation of rare-earth ions were discussed. The changes of the mass transfer coefficients were also investigated. The separation efficiency of the four groups of rareearth elements (REEs) was evaluated based on the elution resolution, Rs, of the elution peaks of La(III), Gd(III), Ho(III) and Lu(III), the four representative elements respectively from each of the four groups of REEs. Experimental results demonstrated that the separation of REEs by liquid-column elution mainly depended on the competitive adsorption of different rare-earth groups onto the surface of ascending P507 oil droplets. The affinity of different rare-earth groups with P507 extractant and a limited adsorption capacity of P507 molecules at the surface of the oil droplets ascending in liquid column play the important role. The present work highlights a promising technique for grouping separation of multiple lanthanide elements co-existing complex systems.
    Separation process study of liquid phase catalytic exchange reaction based on the Pt/C/PTFE catalysts
    Peilong Li, Li Guo, Renjin Xiong, Junhong Luo, Ming Wen, Yong Yao, Zhi Zhang, Jiangfeng Song, Yan Shi, Tao Tang
    2019, 27(8):  1837-1845.  doi:10.1016/j.cjche.2019.01.019
    Abstract ( 174 )   PDF (6189KB) ( 129 )  
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    The liquid phase catalytic exchange (LPCE) reaction is an effective process for heavy water detritiation and production of deuterium-depleted potable water. In the current study, hydrophobic carbon-supported platinum catalysts (Pt/C/PTFE) with high efficiency as reported previously for LPCE were prepared and comprehensive performance evaluation method is applied to evaluate the separation behaviors of LPCE systematically. Experimental results indicate that the optimum reaction temperature of 60-80℃ and the molar feed ratio G/L of 1.5-2.5 would lead to higher separation efficiencies. As to the packing method, a random packing mode with a packing ratio of hydrophobic catalysts 0.25 is recommended. In addition, thermodynamic analysis corresponds well with experimental results under lower temperature and G/L, while the suppression of kinetic factors should not be neglected when T > 80℃ and G/L > 1.5.
    Dual-template synthesis of HZSM-5 zeolites with tailored activity in toluene methylation with CH3Br
    Wuhui Wang, Jun Xie, Peng Wang, Lang Chen, Chaktong Au, Shuangfeng Yin
    2019, 27(8):  1846-1850.  doi:10.1016/j.cjche.2018.10.013
    Abstract ( 187 )   PDF (2310KB) ( 33 )  
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    Shape-selective zeolites (HZ-x/y) were synthesized by a one-pot method using TPAOH (y) and/or MeEt3N+I- (x) as templates. The use of MeEt3N+I- affects the crystal growth and the distribution of acid sites on the external surface of the zeolites. The catalysts show excellent catalytic activity towards toluene alkylation with CH3Br. With toluene conversion of 36.3% and p-xylene selectivity of 66.2%, HZ-40/0 is the most effective among the prepared catalysts, showing a p-xylene yield of 21.2%. The improved para-selectivity is mainly due to the decrease of acid sites on the external surface of the catalysts.
    Selective oxidation of cyclopentene with H2O2 by using H3PW12O40 and TBAB as a phase transfer catalyst
    Yaling Luo, Changjun Liu, Hairong Yue, Siyang Tang, Yingming Zhu, Bin Liang
    2019, 27(8):  1851-1856.  doi:10.1016/j.cjche.2018.10.014
    Abstract ( 232 )   PDF (5165KB) ( 54 )  
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    The selective oxidation of cyclopentene by aqueous H2O2 using H3PW12O40 and tetrabutyl ammonium bromide (TBAB) as a phase transfer catalyst has been investigated. The results show that the presence of TBAB significantly improved the oxidation selectivity of cyclopentene. The effects of the reaction conditions on the conversion of cyclopentene were investigated in detail. The optimal reaction conditions are as follows:the H3PW12O40 to TBAB molar ratio, 1:1-1:3; H3PW12O40 to cyclopentene molar ratio, 0.54:100-0.64:100; and molar ratio of H2O2 to cyclopentene, 1.6:1. The conversion reached to 59.8% in 4 h at 35.0℃, while the selectivity of glutaraldehyde was 38.0% and the selectivity of 1,2-cyclopentanediol was 55.6%. In addition, a route for oxidation of cyclopentene by aqueous H2O2 using a heteropoly acid and quaternary ammonium salt as a phase transfer catalyst was proposed.
    Analysis of long term catalytic performance for isobutane alkylation catalyzed by NMA-AlCl3 based ionic liquid analog
    Pengcheng Hu, Zhitao Wu, Junlin Wang, Yuqing Huang, Yang Deng, Shufeng Zhou
    2019, 27(8):  1857-1862.  doi:10.1016/j.cjche.2018.11.020
    Abstract ( 194 )   PDF (967KB) ( 46 )  
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    Isobutane alkylation with 2-butene to produce high-quality gasoline was catalyzed by N-methylacetamide (NMA)-AlCl3 based ionic liquid (IL) analog with a NMA/AlCl3 molar ratio of 0.75 and CuCl modification, which was marked as CuCl-modified 0.75NMA-1.0AlCl3. The long-term experiment was carried out in the autoclave operated in continuous mode to investigate the distribution of alkylate under different experimental nodes. The result indicated that the long-term alkylation was divided into three stages:rising, stable, and descending regions. C8 selectivity and molar ratio of trimethylpentanes (TMPs) to dimethylhexanes (DMHs) reached the highest level in the stable region, and research octane number (RON) of alkylate was as high as 97. Anionic Al species ([Al2Cl7]-,[AlCuCl5]-) and cationic Al species ([AlCl2L]+) from IL analog as two active Lewis acidic species played a catalytic role in the long-term alkylation, whereas the neutral Al species did not participate into the alkylation. Moreover, the structure of CuCl-modified 0.75NMA-1.0AlCl3 was destroyed after the deactivation, and CuCl was enriched in the CD2Cl2-insoluble substance, resulting in a decreasing TMP/DMH ratio. The catalytic lifetime of IL analog was similar with CuCl-modified 0.55Et3NHCl-1.0AlCl3 IL, but IL analog had a lower cost.
    2-Ethyl-9,10-anthraquinone assisted sol-gel synthesis of Pd/γ-Al2O3 nanorods with enhanced catalytic performance in 2-ethyl-9,10-anthraquinone hydrogenation
    Weiquan Cai, Junlin Zhuo, Jimin Fang, Zhichao Yang
    2019, 27(8):  1863-1869.  doi:10.1016/j.cjche.2019.01.003
    Abstract ( 262 )   PDF (3368KB) ( 48 )  
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    A series of nanorod-like porous Pd/γ-Al2O3 catalysts with controllable textural properties and enhanced catalytic performance in 2-ethyl-9,10-anthraquinone (eAQ) hydrogenation for H2O2 preparation were successfully prepared via a facile sol-gel method using aluminum isopropoxide as aluminum precursor and eAQ as structure directing agent, sequential calcination and impregnation process with Na2PdCl4 solution. The physicochemical properties of the catalysts obtained with different addition amounts of eAQ were comparatively characterized by XRD, TG-DSC, BET, TEM, CO-TPR, H2-TPR and H2-O2 titration. The results show that addition of eAQ can not only effectively control the textural properties (surface area, pore volume and average pore size) of the catalysts, but also lower their reduction temperature of active metal. Importantly, the catalyst obtained with an addition amount of 4 wt% eAQ shows the highest hydrogenation efficiency of 10.28 g·L-1, which is 37.3% higher than 7.49 g·L-1 of the catalyst obtained without eAQ.
    Process Systems Engineering and Process Safety
    Modelling and simulation of two-bed PSA process for separating H2 from methane steam reforming
    Huiru Li, Zuwei Liao, Jingyuan Sun, Binbo Jiang, Jingdai Wang, Yongrong Yang
    2019, 27(8):  1870-1878.  doi:10.1016/j.cjche.2018.11.022
    Abstract ( 310 )   PDF (3998KB) ( 162 )  
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    Methane steam reforming is the main hydrogen production method in the industry. The product of methane steam reforming contains H2, CH4, CO and CO2 and is then purified by pressure swing adsorption (PSA) technology. In this study, a layered two-bed PSA process was designed theoretically to purify H2 from methane steam reforming off gas. The effects of adsorption pressure, adsorption time and purgeto-feed ratio (P/F ratio) on process performance were investigated to design a PSA process with more than 99.95% purity and 80% recovery. Since the feed composition of the PSA process changes with the upstream process, the effect of the feed composition on the process performance was discussed as well. The result showed that the increase of CH4 concentration, which was the weakest adsorbate, would have a negative impact on product purity.
    Process design and economic optimization for the indirect synthesis of dimethyl carbonate from urea and methanol
    Feng Wang, Yanfeng Pu, Jinhai Yang, Taiying Wang, Languang Chen, Ning Zhao, Fukui Xiao
    2019, 27(8):  1879-1887.  doi:10.1016/j.cjche.2018.12.003
    Abstract ( 385 )   PDF (7248KB) ( 60 )  
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    Much attention has been paid for the synthesis of dimethyl carbonate (DMC) by urea indirect alcoholysis method, which had not been actually industrialized by now. The rigorous full process model was then necessary to optimize the process with heat integration. In this paper, a full process was designed and optimized for the DMC synthesis by urea indirect alcoholysis method based on Aspen Plus software. The technological analysis was developed to find how the process was influenced by the three main recycled materials of methanol, 1,2-propylene glycol (PG) and mixture of DMC-methanol. Simultaneously, the thermal optimization was taken into account for energy saving and the optimized process was proposed with heat integration. Moreover, the economic evaluation was implemented for the optimized process with total annualized cost (TAC) and cost of product (COP) according to the plant investment and operations. It was found that the 11.6% decrease in TAC was obtained for the optimized process compared to the original designed process. The COP analysis showed that the process was economically efficient for the production of DMC from urea and methanol.
    An intelligent SVM modeling process for crude oil properties prediction based on a hybrid GA-PSO method
    Kexin Bi, Tong Qiu
    2019, 27(8):  1888-1894.  doi:10.1016/j.cjche.2018.12.015
    Abstract ( 176 )   PDF (3528KB) ( 71 )  
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    Properties prediction of crude oil remains an essential issue for refineries. In this communication, an exhaustive and extendable support vector machine (SVM) intelligent prediction process has been proposed to solve this problem. A novel hybrid genetic algorithm-particle swarm optimization (GA-PSO) method was applied to optimize the SVM model. The optimization process and result demonstrated that the newly proposed GA-PSO-SVM method was more accurate and time-saving than the classical GA or PSO method. Compared with the classical Grid-search SVM, the combined GA-PSO-SVM model appeared to be more applicable for the properties prediction task. The TBP distillation curve fitting was exampled to evaluate the performance of the developed model. The regression result demonstrated the high accuracy and efficiency of the proposed process. The model can be applied in the Industrial Internet as a plugin, and the adaptability and flexibility is demonstrated by the implement of crude oil molecular reconstruction employing the intelligent prediction process.
    Chemical Engineering Thermodynamics
    Interaction of cetyltrimethylammonium bromide with cefixime trihydrate drug at different temperatures and compositions: Effect of different electrolytes
    Marzia Rahman, Md. Anamul Hoque, Malik Abdul Rub, Mohammed Abdullah Khan
    2019, 27(8):  1895-1903.  doi:10.1016/j.cjche.2018.10.022
    Abstract ( 240 )   PDF (2140KB) ( 69 )  
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    Herein, conductivity measurements have been carried out to explore the interaction between cetyltrimethylammonium bromide (CTAB, a cationic surfactant) and antibiotic drug (cefixime trihydrate (CMT)) in water and also in occurrence of inorganic salts (NaCl, Na2SO4 and Na3PO4) over the temperature range of 303.15-323.15 K with an interval of 5 K. In all cases, two critical micelle concentrations (c*) were achieved for the CMT-surfactant system. Addition of CMT drug to CTAB solution decreases the values of c* which indicates the interaction between CMT and CTAB. Both values of c* for CMT-CTAB mixture in the presence of salts are lower in magnitude compared to the aqueous medium which indicates that micellization of the CMT-CTAB mixed system is favorable in salt solution. The values of △Gm0 were obtained to be negative indicating the spontaneity of the micellization process and the extent of spontaneity further increases by means of rising temperature. The obtained outcomes from the △Hm0 and △Sm0 values disclose that the interactions between CMT and CTAB are mostly electrostatic along with hydrophobic in nature. The thermodynamic parameters of transfer and enthalpy-entropy compensation phenomenon were also determined and discussed in detail.
    Experimental studies and artificial neural network modeling of surface tension of aqueous sodium L-prolinate solutions and piperazine blends
    Muhammad Shuaib Shaikh, A. M. Shariff, M. A. Bustam, Sahil Garg, Khadija Qureshi, Pervez Hameed Shaikh, Inamullah Bhatti
    2019, 27(8):  1904-1911.  doi:10.1016/j.cjche.2019.01.006
    Abstract ( 240 )   PDF (3280KB) ( 29 )  
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    The surface tension study is very crucial for the design of CO2 gas absorption contacting equipment. The significance of the surface tension has been increasing due to its consideration in various technological fields. This property influences the mass transfer and hydrodynamics of gas absorption systems, mainly multiphase systems, in which the interface between gas and liquid exists. Therefore, in this study, surface tension of aqueous solutions of sodium L-prolinate (SP) and piperazine (PZ) blends were measured at ten different temperatures from (298.15 to 343.15) K. The SP mass fractions were 0.10, 0.20, and 0.30; while the mass fractions of PZ were 0.02 and 0.05. The experimental results showed that the surface tension increase with increasing the mass fractions of SP and PZ in aqueous blends, and decrease linearly with rising temperature. The experimental data of surface tension were correlated by two empirical correlations as a function of temperature and mass fractions for estimating the predicted data using the optimized correlation coefficients. Moreover, the modeling of surface tension data was carried out using Artificial Neural Network (ANN) approach. The results obtianed from ANN modeling were compared with applied empirical correlation. It was found that the ANN approach outperformed the empirical correlation used in this study. Besides, a quantitative analysis of variation (ANOVA) was performed in order to determine the significance of data. The surface tension of aqueous SP and SP + PZ was also compared with various conventional solvents.
    Implementation of electrolyte CPA EoS to model solubility of CO2 and CO2 + H2S mixtures in aqueous MDEA solutions
    Alireza Afsharpour, Ali Haghtalab
    2019, 27(8):  1912-1920.  doi:10.1016/j.cjche.2019.01.007
    Abstract ( 261 )   PDF (826KB) ( 80 )  
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    The electrolyte version of SRK plus association equation of state (eSRK-CPA EoS) was employed to correlate CO2 solubility in MDEA aqueous solutions. The applied model comprises the classic form of CPA EoS including SRK EoS plus Wertheim association term in addition to MSA theory and Born terms so that the two last terms are responsible for the long-range interactions. A reaction-containing bubble pressure computation technique comprising two nested loops was utilized to model the systems. The internal loop, calculates the liquid phase concentrations via reaction, mass and charge balance equation solving, whereas, the vapor phase concentrations will be obtained in the external one. 470 experimental data were used to correlate binary subsystems and the H2O + MDEA + CO2 ternary system. Since, there not exist any binary VLE data for MDEA + CO2 subsystem, two fitting scenarios were applied. At the first scenario, the binary interaction parameter was assumed equal to zero, while, in second approach the parameter was obtained through ternary system correlation. Both scenarios show very good accuracy in that the Absolute Average Deviation percentages (AAD) obtained were 19.12% and 18.85%, respectively. Also, to show the efficiency of the used model, a comparison between our results and those of the best-known models was made. Finally, having model parameters for H2S solubility from our previous work[A. Afsharpour, Petroleum Science and Technology 35 (3) (2017) 292-298], simultaneous solubility of CO2 + H2S mixtures in MDEA solutions was predicted using the eSRK-CPA EoS with no new optimizable parameters. As the results show, the applied model has a good performance for correlation and prediction of acid gas solubility in a wide range of pressures, temperatures, acid gas loadings, and MDEA concentrations.
    Review on the applications and developments of drag reducing polymer in turbulent pipe flow
    M. A. Asidin, E. Suali, T. Jusnukin, F. A. Lahin
    2019, 27(8):  1921-1932.  doi:10.1016/j.cjche.2019.03.003
    Abstract ( 298 )   PDF (5119KB) ( 198 )  
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    Drag reduction phenomenon in pipelines has received lots of attention during the past decades due to its potential engineering applications, especially in fluid transporting industries. Various methods to enhance drag reduction have been developed throughout the years and divided into two categories; non-additives method and additives method. Both categories have different types of methods, with different formulations and applications which will generally be discussed in this review. Among all the methods discussed, drag reduction using polymer additive is as one of the most enticing and desirable methods. It has been the subject of research in this field and has been studied extensively for quite some time. It is due to its ability to reduce drag up to 80% when added in minute concentrations. Reducing drag in the pipe will require less pumping power thus offering economic relieves to the industries. So, this paper will be focusing more on the use of polymer additives as drag reducing agent, the general formulations of the additives, major issues involving the use of drag reducing polymers, and the potential applications of it. However, despite the extensive works of drag reduction polymer, there are still no models that accurately explain the mechanism of drag reduction. More studies needed to be done to have a better understanding of the phenomenon. Therefore, future research areas and potential approaches are proposed for future work.
    Biotechnology and Bioengineering
    Catalytic depolymerization of calcium lignosulfonate by NiMgFeOx derived from sub-micron sized NiMgFe hydrotalcite prepared by introducing hydroxyl compounds
    Hongjing Han, Jinxin Li, Haiying Wang, Feng Xue, Yanguang Chen, Yanan Zhang, Yizhen Wang, Mei Zhang
    2019, 27(8):  1933-1938.  doi:10.1016/j.cjche.2019.01.024
    Abstract ( 160 )   PDF (6954KB) ( 15 )  
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    A new method for regulating the synthesis of NiMgFe hydrotalcites (NMF LDHs) with the addition of hydroxyl compounds was proposed. A series of NMF LDHs were prepared by the above method, and then were calcined to obtain the NiMgFeOx (NMFOx) samples. The NMFOx samples were characterized by XRD, SEM, TG-DTG, XPS and CO2-TPD, respectively. The catalytic performance of NMFOx for depolymerizing calcium lignosulfonate (CLS) was evaluated by hydrothermal reaction. The results showed that the addition of hydroxyl compounds favored reducing the particle sizes of NMF LDHs. For the depolymerization of CSL, the yield of liquid product increased from 45% to 75.8% with the addition of NMFOx-ethanol (NMFOxET). The liquid products were mainly phenolics, aromatics, ketones and esters. The total selectivity of oxy-containing compounds was over 90.6%, among them, the phenolics were approximately 35.2%. The valence of Ni and Fe, crystalline phase and basicity almost remained unchanged. The NMFOx-ET samples were recycled for the depolymerization of CLS, moreover, the NMFOx-ET samples had high activity and stability after 4 cycles.
    Energy, Resources and Environmental Technology
    Production of aryl oxygen-containing compounds from catalytic pyrolysis of bagasse lignin over LaTixFe1-xO3
    Haiying Wang, Hongjing Han, Enhao Sun, Yanan Zhang, Jinxin Li, Yanguang Chen, Hua Song, Hongzhi Zhao
    2019, 27(8):  1939-1944.  doi:10.1016/j.cjche.2019.01.023
    Abstract ( 189 )   PDF (3037KB) ( 32 )  
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    A new approach, named production of aryl oxygen-containing compounds from the catalytic pyrolysis of bagasse lignin (BL) over perovskite oxide, was proposed. A series of LaTixFe1-xO3 (LTF-x) samples were prepared by the solid state reaction method. The crystal phase and morphology of LTF-x were characterized by XRD and SEM respectively. Catalytic pyrolysis performance of LTF-x was performed by TG-DTG and the distribution patterns of gaseous, liquid and solid products from BL was investigated using a fixed-bed micro-reactor. The optimal reaction conditions were determined:the pyrolysis temperature was 600℃, the mass ratio of mBL:mLTF-0.2 was 3:1, the velocity of carrier gas was 100 ml·min-1. The gaseous products were mainly composed of CO2, CO, CH4 and CnHm (n=2-4, m=2n + 2 or m=2n). The main aryl oxygen-containing compounds in liquid products were phenolics, guaiacols, syringols and phenylates, the rest were benzenes, furans, esters and carboxylic acid. The total contents of aryl oxygencontaining compounds were from 62% up to more than 72% under the action of the perovskite. Moreover, the LTF-0.2 sample had nice regenerability.
    Assessment of Cu (II) removal from an aqueous solution by raw Gundelia tournefortii as a new low-cost biosorbent: Experiments and modelling
    Saba Golshan Shandi, Faramarz Doulati Ardejani, Fereydoun Sharifi
    2019, 27(8):  1945-1955.  doi:10.1016/j.cjche.2018.12.027
    Abstract ( 213 )   PDF (8793KB) ( 15 )  
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    Lignocellulosic materials can be used as biosorbent for refinement of the wastewaters when they are available in large quantities. Many studies were conducted to uptake Cu (II) ion from aqueous solutions. In this paper, the biosorption efficiency of Cu (II) ions from a synthetic aqueous solution was investigated using Gundelia tournefortii (GT), without any pre-treatment. Fourier transform infrared spectroscopy, scanning electron microscopy and determining the point of zero charge were employed to characterise the biosorbent. Batch experiments were performed to study the influence of pH, biosorbent dosage, contact time, temperature and initial Cu (II) concentration on Cu (II) removal. The biosorption isotherms were investigated using the Langmuir, Freundlich, Temkin and D-R isotherm models. The findings show that the biosorption isotherm was better fitted by the Langmuir equation and the maximum adsorption capacity of GT was found to be 38.7597 mg·g-1. The kinetics data were analysed by pseudo-first order, pseudo-second order, and intra-particle diffusion equations. The results indicate that the pseudosecond-order model was found to explain the adsorption kinetics most effectively. The values of thermodynamic parameters including Gibbs free energy (△G°), enthalpy (△H°), and entropy (△S°) demonstrate that the biosorption process was exothermic and spontaneous. The multiple nonlinear regression (MnLR) and artificial neural network (ANN) analyses were applied for the prediction of biosorption capacity. A relationship between the predicted and observed data was obtained and the results show that the MnLR and ANN models provided successful predictions.
    Experimental study on the effect of H2S and SO2 on high temperature corrosion of 12Cr1MoV
    Hong Xu, Shangkun Zhou, Yiming Zhu, Weigang Xu, Xiaohe Xiong, Houzhang Tan
    2019, 27(8):  1956-1964.  doi:10.1016/j.cjche.2018.12.020
    Abstract ( 194 )   PDF (6277KB) ( 63 )  
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    Aiming at the high temperature corrosion in a coal-fired boiler, the effect of H2S and SO2 on the corrosion of 12Cr1MoV under the water wall condition has been investigated by experiments. The results indicate that H2S can promote the corrosion significantly, and the coarse porous oxide film formed cannot stop the progress of corrosion. While SO2 presents little effect on the corrosion. The main composition of the surface of 12Cr1MoV corrosion products is Fe2O3. With H2S in the atmosphere, the corrosion gradually develops into deeper layers by forming FeS, FeO and Fe2O3 alternately. The corrosion rate is doubled for every 50℃ increase in temperature at 400-500℃.
    Materials and Product Engineering
    Silicon saturation coefficient changes in hydrogarnets during the Bayer process with lime addition
    Guozhi Lü, Ting'an Zhang, Xiaofeng Zhu, Chaozhen Zheng, Yanxiu Wang, Weiguang Zhang, Zimu Zhang
    2019, 27(8):  1965-1972.  doi:10.1016/j.cjche.2018.10.016
    Abstract ( 140 )   PDF (9776KB) ( 14 )  
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    The relationship between the silicon saturation coefficient of hydrogarnets and Bayer reaction parameters was studied. The peak position, crystal plane spacing, and cell edge length of typical hydrogarnet patterns were calculated to find the key factors influencing the relationship. The results showed that the crystal face (420) is the optimal garnet growth direction during hydration and crystal growth along the faces (521) and (611) were not affected significantly by the varying experimental conditions. The reaction temperature significantly influenced the silicon saturation coefficient of hydrogarnets. The silicon saturation coefficient of hydrogarnets increased from 0.2 to about 1.0 in the temperature range of 30-270℃ and a rapid expansion process was observed in the temperature range of 120-150℃. Moreover, the reaction time, alumina concentration, and C/S were shown to be less important factors. Averaging the results obtained by the 3 methods was shown suitable for calculating the SiO2 saturation coefficient of hydrogarnets. The calculated results of the Al2O3 and SiO2 contents matched the actual ones. However, the actual SiO2 content was about 10% less than the calculated one for SiO2 saturation coefficients higher than 1.
    Adsorption of methyl orange from aqueous solution by composite magnetic microspheres of chitosan and quaternary ammonium chitosan derivative
    Bin Zhao, Xiaojing Sun, Liang Wang, Lixiang Zhao, Zhaohui Zhang, Junjing Li
    2019, 27(8):  1973-1980.  doi:10.1016/j.cjche.2018.12.014
    Abstract ( 211 )   PDF (3356KB) ( 87 )  
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    Novel composite magnetic microspheres containing chitosan and quaternary ammonium chitosan derivative (CHMMs) were prepared by inverse suspension method, and used for the methyl orange (MO) removal from aqueous solutions. The CHMMs were characterized by a scanning electron microscope, a transmission electron microscope, and Fourier transform infrared spectroscopy, respectively. Compared with the chitosan beads, the incorporation of quaternary ammonium chitosan derivative significantly reduced the particle size. The MO adsorption by CHMMs was investigated by batch adsorption experiments. The adsorption kinetics was conformed to the pseudo second-order kinetics equation. The adsorption isotherm followed the Langmuir model better than the Freundlich model and the calculated maximum MO adsorption capacity was 266.6 mg·g-1 at 293 K. Thermodynamic studies indicated that the MO adsorption was endothermic in nature with the enthalpy change (ΔH°) of 99.44 kJ·mol-1. The CHMMs had a stable performance for MO adsorption in the pH range of 4-10, but high ionic strength deteriorated the MO removal due to the shielding of the ion exchange interaction. A 1 mol·L-1 NaCl solution could be used to regenerate the exhausted CHMMs. The proposed CHMMs can be used as an effective adsorbent for dye removal or recovery from the dye wastewater.
    Modification of pillared MFI zeolite nanosheets by nitridation with tailored activity in benzylation of mesitylene and benzyl alcohol
    Zhipeng Chen, Jiajin Huang, Qiaowen Mu, Huiyong Chen, Feng Xu, Yanxiong Fang, Baoyu Liu
    2019, 27(8):  1981-1987.  doi:10.1016/j.cjche.2019.03.027
    Abstract ( 148 )   PDF (2716KB) ( 42 )  
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    The modification of pillared MFI zeolites was performed by nitridation of silica pillared MFI zeolite nanosheets under NH3 atmosphere with different time. The resultant zeolites were characterized by a complementary combination of X-ray power diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), pyridine-IR spectroscopy and N2 adsorption-desorption isotherms. The analyses showed that the nitridation didn't destroy the crystallinity and specific surface area of zeolites, and the acidity of zeolites can be tailored by tuning the time of nitridation, resulting in the different concentration ratios of Brønsted-to-Lewis (B/L) acid sites. Moreover, the nitrided zeolites exhibited high selectivity to 2-benzyl-1,3,5-trimethylbenzene than parent silica pillared MFI zeolite nanosheets in benzylation of mesitylene with benzyl alcohol. A balance between Brønsted acid sites and Lewis acid sites can inhibit the self-etherification of benzyl alcohol and enhance the selectivity of alkylated product. These experimental data implied that nitridation was an effective method to modulate the acidity of zeolites and the synergy between Brønsted acid sites and Lewis acid sites was a decisive factor to determine the selectivity.
    Spongy acetylenic carbon material prepared by ball milling CaC2 and chlorinated rubber-Its mercury adsorption and electrochemical property
    Xuebing Xu, Wenfeng Li, Luyan Xia, Yingzhou Lu, Hong Meng, Chunxi Li
    2019, 27(8):  1988-1995.  doi:10.1016/j.cjche.2019.05.005
    Abstract ( 214 )   PDF (3228KB) ( 28 )  
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    Design and preparation of novel advanced carbon materials with unique architecture and functional groups is of great significance. Herein, a spongy acetylenic carbon material (SACM) was prepared through mechanochemical reaction of CaC2 and chlorinated rubber in a planetary ball mill at ambient temperature. Its composition and structure were characterized, and its electrochemical properties and adsorption performance for Hg2+ were studied. The SACM is composed of submicron spongy aggregates with high carbon content (81.8%) and specific area (503.9 m2·g-1), rich porosity and acetylenic groups. The SACM exhibits excellent adsorption for Hg2+ with saturated adsorption amount being 157.1 mg·g-1, which is superior to conventional carbon materials. Further, it exhibits good electrochemical performance with low equivalent series resistance (0.50 Ω), excellent cycling stability and ideal double layer capacitive behavior. This paper provides a novel and universal synthesis method of spongy carbon materials, and better results can be expected through tuning the pore structure, graphitization degree, and heteroatoms of the target carbon materials.