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Table of Content
28 March 2018, Volume 26 Issue 3
    Fluid Dynamics and Transport Phenomena
    Numerical investigation on flow and heat transfer characteristics of corrugated tubes with non-uniform corrugation in turbulent flow
    Dongwei Zhang, Hanzhong Tao, Yuan Xu, Zishuai Sun
    2018, 26(3):  437-444.  doi:10.1016/j.cjche.2017.03.038
    Abstract ( 1185 )   PDF (1015KB) ( 55 )  
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    Based on finite volume method, the pressure drop and heat transfer characteristics of one smooth tube and ten different axisymmetric corrugated tubes, including two with uniform corrugation and eight with non-uniform corrugation, have been studied. A physical model of the corrugated tube was built, then the numerical simulation of the model was carried out and the numerical simulation results were compared with the empirical formula. The results show that:the friction factor decreases with the increase of Reynolds number ranging from 6000 to 57000, the value of which in the corrugated tubes with non-uniform corrugation (tube 03-10) are smaller than those with uniform corrugation (tube 01-02). The geometry parameters of tube (01) have advantages on the heat transfer enhancement in low Reynolds number flow region (from 6000 to 13000) and tube (07-08) have advantages on the heat transfer enhancement in high Reynolds number flow region (from 13000 to 57000). The vortex, existed in each area between two adjacent corrugations called second flow region, is the root of the enhancement on heat transfer in the corrugated tubes. The effectiveness factor decreases with the increasing of Reynolds number and the performances of the corrugated tubes with pitch of 12.5 mm have advantages than these of 10 mm under the same corrugation geometric parameter.
    Investigations on pool boiling critical heat flux, transient characteristics and bonding strength of heater wire with aqua based reduced graphene oxide nanofluids
    R. Kamatchi, G. Kumaresan
    2018, 26(3):  445-454.  doi:10.1016/j.cjche.2017.12.006
    Abstract ( 1119 )   PDF (1038KB) ( 34 )  
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    In the present work, the pool boiling critical heat flux, transient heat transfer characteristics, and bonding strength of thin Ni-Cr wire with aqua based reduced graphene oxide (rGO) nanofluids are experimentally studied. Results indicate:(i) the critical heat flux (CHF) of 0.01, 0.05, 0.1, 0.2, and 0.3 g·L-1 concentrations of rGO-water nanofluids varies from 1.42 to 2.40 MW·m-2; (ii) the CHF remains same for the tested samples during transient heat transfer studies and (iii) a constant value of CHF upto 10 tests when the nanocoated Ni-Cr wire is tested with DI water and deterioration occurs beyond this which implies a chance of peel off of rGO layer below the critical coating thickness.
    Separation Science and Engineering
    Heavy metals adsorption by banana peels micro-powder: Equilibrium modeling by non-linear models
    Giorgio Vilardi, Luca Di Palma, Nicola Verdone
    2018, 26(3):  455-464.  doi:10.1016/j.cjche.2017.06.026
    Abstract ( 1371 )   PDF (695KB) ( 256 )  
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    In this study the copper and lead adsorption efficiency onto banana peels powder was investigated. The agroindustrial waste recovery represents one of the Circular Economy pillars. In the view of the synthesis of an environmentally friendly adsorbent material, the powder was used without any preliminary chemical or thermal activation, but only after simple washing, drying and grinding. The bio-adsorbent was characterized by the FTIR technique and tested in batch mode on synthetic aqueous solutions containing Pb and Cu in the range 10-90 mg·L-1. A selection of two (Langmuir, Freundlich) and three (Sips, Redlich-Peterson, Koble-Corrigan) parameter isotherm models was chosen to fit adsorption equilibrium data by non-linear regression procedure. The best fit isotherm model was selected relying on the error function with the lowest average percentage error (APE) value, among those characterized by the highest R2 values. As expected, the three-parameter models are found to better represent both metals bio-adsorption, with APE and R2 values always lower and higher, respectively, than the corresponding values obtained for the two-parameter models.
    Potential aspect of rice husk biomass in Australia for nanocrystalline cellulose production
    Md. Sakinul Islam, Nhol Kao, Sati N. Bhattacharya, Rahul Gupta, Hyoung Jin Choi
    2018, 26(3):  465-476.  doi:10.1016/j.cjche.2017.07.004
    Abstract ( 1309 )   PDF (1162KB) ( 208 )  
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    Nanocrystalline cellulose (NCC) was produced from rice husk biomass (Oryza sativa) by a chemical extraction process to explore the potential aspect of agro-waste biomass in Australia. In this work, the delignified rice husk pulp (D-RHP) was produced by alkaline delignification of raw rice husk biomass (R-RHB) using 4 mol·L-1 alkali solutions (NaOH) in a jacketed glass reactor under specific experimental conditions. D-RHP was bleached using 15% sodium hypochlorite, and the bleached rice husk pulp was coded as B-RHP. Finally, raw suspension of NCC was produced by the acid hydrolysis of B-RHP using 4 mol·L-1 sulphuric acid. The raw suspension of NCC was neutralized by a buffer solution and analyzed by TAPPI, FT-IR, XRD, SEM, AFM, and TEM. FT-IR spectra of NCC are different to R-RHB but similar with B-RHP and D-RHP. From XRD results, the crystallinity of NCC was found to be approximately 65%. In AFM analysis particle thicknesses have been confirmed to be in the range of (25 ±15.14) nm or (27 ±15.14) nm which is almost the same. From TEM analysis particle dimensions have been confirmed to be in the range of (50 ±29.38) nm width and (550 ±302.75) nm length with the aspect ratio~11:1 (length/diameter) at a 500 nm scale bar. On the other hand, at a 200 nm scale bar the particle dimensions have been confirmed to be in the range of (35 ±17) nm width and (275 ±151.38) nm length with the aspect ratio~8:1. The aspect ratio of individual crystalline domain was determined in TEM analysis which is 10:1 (100/10). Therefore the aspect ratios and dimensions of nanoparticles in NCC suspension are almost the same and in nano-meter scale, as confirmed from both AFM and TEM results. The yield of NCC from B-RHP was found to be approximately 95%, and the recovery of cellulose from R-RHB is about 90%.
    Fouling evaluation on membrane distillation used for reducing solvent in polyphenol rich propolis extract
    Norhaziyana Hamzah, Choe Peng Leo
    2018, 26(3):  477-483.  doi:10.1016/j.cjche.2017.03.041
    Abstract ( 1202 )   PDF (1064KB) ( 56 )  
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    Membrane distillation (MD) has not been widely studied in the concentrate of phenolic rich solution in comparison to osmotic distillation. In this work, the potential of MD to reduce solvent in the polyphenol rich propolis extract was further investigated. Polyvinylidene fluoride (PVDF) membranes were engineered with the smaller pore size for the less hydrophobic surface in order to avoid wetting, allowing only the solvent vapor to be transferred from the warm feed into the cold permeate. All the membranes exhibited more than 95% rejection of phenolic and flavonoid compounds. Although the hydrophilic membranes exhibited less fouling, they displayed a lower flux than the hydrophobic membrane due to the hindrance in the wetted pores. The hydrophobic membrane was seriously fouled by the phenolic acid as shown in the Fourier transform infrared spectroscopy spectrum. Pore plugging occurred on these hydrophobic membranes as confirmed in the scanning electron microscope images.
    Investigation on a vertical radial flow adsorber designed by a novel parallel connection method
    Zhengshu Dai, Meng Yu, Daozhe Rui, Xuejun Zhang, Yang Zhao
    2018, 26(3):  484-493.  doi:10.1016/j.cjche.2017.11.005
    Abstract ( 1453 )   PDF (1020KB) ( 57 )  
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    Due to the increasing global demand for industrial gas, the development of large-scale cryogenic air separation systems has attracted considerable attention in recent years. Increasing the height of the adsorption bed in a vertical radial flow adsorber used in cryogenic air separation systems may efficiently increase the treatment capacity of the air in the adsorber. However, uniformity of the flow distribution of the air inside the adsorber would be deteriorated using the height-increasing method. In order to reduce the non-uniformity of the flow distribution caused by the excessive height of adsorption bed in a vertical radial flow adsorber, a novel parallel connection method is proposed in the present work. The experimental apparatus is designed and constructed; the Computational Fluid Dynamics (CFD) technique is used to develop a CFD-based model, which is used to analyze the flow distribution, the static pressure drop and the radial velocity in the newly designed adsorber. In addition, the geometric parameters of annular flow channels and the adsorption bed thickness of the upper unit in the parallelconnected vertical radial flow adsorber are optimized, so that the upper and lower adsorption units could be penetrated by air simultaneously. Comparisons are made between the height-increasing method and the parallel connection method with the same adsorber height. It is shown that using the parallel connection method could reduce the difference between the maximum and minimum radial static pressure drop by 86.2% and improve the uniformity by 80% compared with those of using the height-increasing method. The optimal thickness ratio of the upper and lower adsorption units is obtained as 0.966, in which case the upper and lower adsorption units could be penetrated by air simultaneously, so that the adsorbents in adsorption space could be used more efficiently.
    Synthesis, adsorption and selectivity of inverse emulsion Cd(II) imprinted polymers
    Luwei Li, Fang Zhu, Yanhong Lu, Jian Guan
    2018, 26(3):  494-500.  doi:10.1016/j.cjche.2017.08.014
    Abstract ( 1013 )   PDF (692KB) ( 21 )  
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    Inverse emulsion polymerization was employed to synthesize inverse emulsion Cd(Ⅱ) imprinted polymers (IEⅡ P). The morphology and functional groups of IEⅡP were characterized by SEM,FTIR and TG. Static adsorption experiments and competitive adsorption test were used to evaluate the adsorption ability of IEⅡP. The adsorption capacity of polymers could reach 86.7 mg·g-1 under the optimal adsorption conditions. The pseudo second order kinetic model and Langmuir isotherm model could be used to analyze the experimental data well. The adsorption process of IEⅡP was chemical adsorption process and monomolecular type. Thermodynamic parameters showed that the adsorption process was endothermic and could occur spontaneously. The selectivity coefficients k of Cd2+/v, Cd2+/Zn2+ and Cd2+/Cu2+ were 2.4998, 1.2437 and 4.6882, respectively. The proposed method provides a new thought for removing Cd(Ⅱ) in water samples.
    Partial pore blockage and polymer chain rigidification phenomena in PEO/ZIF-8 mixed matrix membranes synthesized by in situ polymerization
    Xiaoli Ding, Xu Li, Hongyong Zhao, Ran Wang, Runqing Zhao, Hong Li, Yuzhong Zhang
    2018, 26(3):  501-508.  doi:10.1016/j.cjche.2017.07.017
    Abstract ( 1106 )   PDF (1139KB) ( 38 )  
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    Nanostructured zeolitic imidazolate frameworks (ZIF-8) was incorporated into the mixture of poly (ethylene glycol) methyl ether acrylate (PEGMEA) and pentaerythritol triacrylate (PETA) to synthesize mixed matrix membranes (MMMs) by in situ polymerization for CO2/CH4 separation. The solvent-free polymerization between PEGMEA and PETA was induced by UV light with 1-hydroxylcyclohexyl phenyl ketone as initiator. The chemical structural characterization was performed by Fourier transform infrared spectroscopy. The morphology was characterized by scanning electron microscope. The average chain-to-chain distance of the polymer chains in MMMs was investigated by X-ray diffraction. The thermal property was evaluated by differential scanning calorimetry. The CH4 and CO2 gas transport properties of MMMs are reported. The relationship between gas permeation-separation performances or physical properties and ZIF-8 loading is also discussed. However, the permeation-separation performance was not improved in Robeson upper bound plot compared with original polymer membrane as predicted. The significant partial pore blockage and polymer rigidification effect around the ZIFs confirmed by the increase in glass temperature and the decrease in the d-spacing, were mainly responsible for the failure in performance improvement, which offset the high diffusion induced by porous ZIF-8.
    Catalysis, kinetics and reaction engineering
    Effect of boron addition on the MoO3/CeO2-Al2O3 catalyst in the sulfur-resistant methanation
    Baowei Wang, Wenxia Yu, Weihan Wang, Zhenhua Li, Yan Xu, Xinbin M
    2018, 26(3):  509-513.  doi:10.1016/j.cjche.2017.08.011
    Abstract ( 969 )   PDF (1556KB) ( 21 )  
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    The effect of boron on the performance of MoO3/CeO2-Al2O3 catalysts, which were prepared with impregnation method, was investigated. The catalysts were characterized with N2 adsorption-desorption, XRD, H2-TPR, and NH3-TPD, and were tested in sulfur-resistant methanation. The results indicated that the MoO3/CeO2-Al2O3 catalysts modified by boron showed higher catalytic performance in sulfur-resistant methanation. The CO conversion increased from 47% to 62% with 0.5 wt% boron content. When the content of boron was under 0.5 wt%, the results suggested there was an increase in the amorphous form of MoO3 caused by the generation of weak and intermediate acid sites, which had weakened the interaction between the active components and supports. While, the catalyst added 2.0 wt% boron showed the strong acid sites and the largest crystalline size resulting in the uneven distribution of ceria.
    Free radical reaction model for n-pentane pyrolysis
    Cong Zhou, Yuanyi Yang, Wei Li, Ying Shi, Li Jin, Zhaobin Zhang, Guoqing Wang
    2018, 26(3):  514-520.  doi:10.1016/j.cjche.2017.06.024
    Abstract ( 999 )   PDF (950KB) ( 41 )  
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    A mathematical mechanism of the n-pentane pyrolysis process based on free radical reaction model was presented. The kinetic parameters of n-pentane pyrolysis are obtained by quantum chemistry and the reaction network is established. The solution of the stiff ordinary differential equations in the n-pentane pyrolysis model is completed by semi implicit Eular algorithm. Then the pyrolysis mechanism based on free radical reaction model is built, and the computational efficiency increases 10 times by algorithm optimization. The validity of this model and its solution method is confirmed by the experimental results of n-pentane pyrolysis.
    Benzene selective hydrogenation over supported Ni (nano-) particles catalysts: Catalytic and kinetics studies
    M. H. Peyrovi, N. Parsafard, Z. Mohammadian
    2018, 26(3):  521-528.  doi:10.1016/j.cjche.2017.05.022
    Abstract ( 1116 )   PDF (1137KB) ( 169 )  
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    This report aims to reduce the benzene in a mixture of benzene and toluene as a model reaction using catalytic hydrogenation. In this research, we developed a series of catalysts with different supports such as Ni/HMS, Ni/HZSM-5, Ni/HZSM5-HMS, Ni/Al2O3 and Ni/SiO2. Kinetic of this reaction was investigated under various hydrogen and benzene pressures. For more study, two kinetic models have also been selected and tested to describe the kinetics for this reaction. Both used models, the power law and Langmuir-Hinshelwood, provided a good fit toward the experimental data and allowed to determine the kinetic parameters. Among these catalysts, Ni/Al2O3 showed the maximum benzene conversion (99.19%) at 130℃ for benzene hydrogenation. The lowest toluene conversion was observed for Ni/SiO2. Furthermore, this catalyst presented high selectivity to benzene (75.26%) at 130℃. The catalytic performance (activity, selectivity and stability) and kinetics evaluations were shown that the Ni/SiO2 is an effective catalyst to hydrogenate benzene. It seems that the surface properties particularly pore size are effective parameter compared to other factors such as acidity and metal dispersion in this process.
    Indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with TiO2 in the presence of hole scavengers
    Abdus Samad, Shamim Ahsan, Ikki Tateishi, Mai Furukawa, Hideyuki Katsumata, Tohru Suzuki, Satoshi Kaneco
    2018, 26(3):  529-533.  doi:10.1016/j.cjche.2017.05.019
    Abstract ( 1181 )   PDF (739KB) ( 61 )  
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    The indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with titanium dioxide (TiO2) was investigated with various hole scavengers such as methanol, ethanol, 2-propanol, formaldehyde, acetone, formic acid and acetic acid. Although the direct photocatalytic reduction of arsenate to arsenite with TiO2 was impossible, an indirect reduction of As(V) was possible in the presence of sacrificial electron donors to form strongly reductive radicals. The addition of ethanol was very effective for indirect photocatalytic reduction of As(V) in aqueous solution with TiO2 photocatalyst. The indirect photocatalytic reduction rate of As(V) may be related with both the reaction rate constants of reaction of hydroxyl radicals with hole scavenger and the reactivities for the radicals M· which are produced by the reaction of ·OH with hole scavenger.
    Pd catalysts supported on rGO-TiO2 composites for direct synthesis of H2O2: Modification of Pd2+/Pd0 ratio and hydrophilic property
    Shuying Chen, Rui Tu, Jun Li, Xiaohua Lu
    2018, 26(3):  534-539.  doi:10.1016/j.cjche.2017.07.016
    Abstract ( 1075 )   PDF (843KB) ( 32 )  
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    The use of nanostructured composites as catalyst supports is a promising route to prepare catalysts with high selectivity and productivity. In this work, reduced graphene oxide-TiO2 (rGP-x) composites with a variation of reduced graphene oxide (rGO) content were synthesized by hydrothermal method. Pd/rGP-x catalysts were prepared in incipient-wetness impregnation method for the direct synthesis of H2O2 from H2 and O2. The morphology and electronic properties of catalysts were investigated by XPS, TEM, and Raman spectroscopy. The ratio of Pd2+/Pd0 and the hydrophobicity of the catalysts were increased with the rising content of rGO. As the amount of rGO in the catalysts varied in the range of 0.025 wt%-2 wt%, the selectivity of H2O2 exhibited a tendency of increasing firstly and then decreasing from 0.1 wt% to 2 wt%. It indicates that good catalytic performance for H2O2 synthesis can be achieved only when appropriate amount of rGO is introduced. The H2O2 selectivity and productivity of Pd/rGP-0.025 both improved remarkably compared with Pd/P25. This enhancement originated from the combined effects of the proper ratio of Pd2+/Pd0 and hydrophobicity of the catalyst.
    Preparation of highly active MCM-41 supported Ni2P catalysts and its dibenzothiophene HDS performanc
    Hua Song, Qi Yu, Yanguang Chen, Yuanyuan Wang, Ruixia Niu
    2018, 26(3):  540-544.  doi:10.1016/j.cjche.2017.09.001
    Abstract ( 907 )   PDF (605KB) ( 55 )  
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    Highly active MCM-41 supported nickel phosphide catalysts for hydrodesulfurization (HDS) were synthesized by two different phosphorus sources, in which the surface of Ni2P catalysts were modified by air instead of being passivated by O2/N2 mixture. In addition, the catalysts need not be activated with flowing H2 (30 ml·min-1) at 500℃ for 2 h prior to reaction as traditional method. X-ray diffraction (XRD), X-ray photoelectro spectroscopy (XPS), N2-adsorption specific surface area measurements and CO chemisorption were used to characterize the resulting catalysts. The effect of modification with air on the surface of the catalysts for HDS performance was investigated. Results showed that the surface modification with air can promote the formation of smaller Ni2P particles and more active Ni sites on surface of catalysts. At 3.0 MPa and 613 K, the dibenzothiophene (DBT) conversion of the catalysts modified with air was 98.7%, which was 7.1% higher than that of catalyst passivated by O2/N2 mixture. The higher activities of Ni2P(x)/M41-O catalysts can be attributed to the smaller Ni2P particles sizes and the increased hydrogen dissociation activity due to the surface modification.
    Dealumination kinetics of composite ZSM-5/mordenite zeolite during steam treatment: An in-situ DRIFTS study
    Xiaoxiao Zhang, Dangguo Cheng, Fengqiu Chen, Xiaoli Zhan
    2018, 26(3):  545-550.  doi:10.1016/j.cjche.2017.11.009
    Abstract ( 1177 )   PDF (719KB) ( 27 )  
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    To get a better understanding of structural deactivation of ZSM-5/MOR during the catalytic cracking of n-heptane in the steam atmosphere, a comprehensive mechanism of hydrothermal dealumination was proposed through in-situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) in this work. The mechanism can be divided into two steps:firstly, the hydrolysis of four Al-O bonds, and secondly, the self-healing of Si-OH bonds accompanied with partial condensation of the extra-framework Al species. Accordingly, the kinetics of dealumination process has also been fully discussed. In the IR spectra, the range of 3450-3850 cm-1 could be deconvolved to distinguish the hydroxyl groups on the different position and calculate the consumption of each hydroxyl group during the reaction. Based on results from the in-situ DRIFTS, the kinetics of dealumination was hence developed and also in well agreement with the kinetics of deactivation of ZSM/MOR catalysts during the reaction in the presence of little coke deposits.
    Chemical Engineering Thermodynamics
    An improved theoretical procedure for the pore-size analysis of activated carbon by gas adsorption
    Guodong Wang, Jianchun Jiang, Kang Sun, Jianzhong Wu
    2018, 26(3):  551-559.  doi:10.1016/j.cjche.2017.09.021
    Abstract ( 1197 )   PDF (1022KB) ( 102 )  
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    Amorphous carbon materials play a vital role in adsorbed natural gas (ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation (AIE), the pore-size distribution (PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory (DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However, rarely considered is the accuracy of the mean-field approximation (MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo (GCMC) molecular simulation for the adsorption of CH4 and CO2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu (WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO2 isotherms. In particular, those distributions in the feature pore width range (FPWR) are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.
    Isobaric vapor-liquid equilibrium for ternary system of ethanol, ethyl propionate and para-xylene at 101.3 kPa
    Zhongpeng Xing, Yujie Gao, Hui Ding, Xianqin Wang, Lujun Li, Hang Zhou
    2018, 26(3):  560-565.  doi:10.1016/j.cjche.2017.10.020
    Abstract ( 1349 )   PDF (239KB) ( 86 )  
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    Isobaric vapor-liquid equilibrium (VLE) data for the binary system ethyl propionate (2) + para-xylene (3) and ternary system ethanol (1) + ethyl propionate (2) + para-xylene (2) at atmospheric pressure (101.3 kPa) were obtained by a VLE modified othmer still. All the experimental data passed a point to point consistency test of Van Ness method, which verified the data reliability. The Wilson and UNIQUAC activity coefficient models were employed to correlate the binary VLE data to obtain binary interaction parameters. Based on binary interaction parameters, ternary VLE data of ethanol (1) + ethyl propionate (2) + para-xylene (3) were predicted by Wilson and UNIQUAC models, which proved that predicted values are consistent with the experimental data. Furthermore, azeotropic phenomenon between ethanol and ethyl propionate disappears when the mole ratio of para-xylene and binary system of ethanol and ethyl propionate is 1:1. Therefore, this paper convinced that para-xylene is a proper extractive additive that could be used in extractive distillation to separate the binary azeotropic system of ethanol and ethyl propionate.
    Interaction of antipsychotic drug with novel surfactants: Micellization and binding studies
    Naved Azum, Malik Abdul Rub, Abdullah M. Asiri
    2018, 26(3):  566-573.  doi:10.1016/j.cjche.2017.09.009
    Abstract ( 1228 )   PDF (857KB) ( 46 )  
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    The interaction of cationic gemini surfactants (alkanediyl-α,ω-bis(alkyl dimethylammonium bromide)) with an antipsychotic drug (chlorpromazine hydrochloride (CPZ)) has been investigated. Various micellar and interfacial parameters have been deliberated by surface tension measurement to report the nature of interactions between drug and novel surfactant mixtures. The behavior of mixed systems, their compositions and activities of components have been analyzed in the light of Rubingh's theory. The results indicate synergism in the binary mixtures. The binding study between CPZ and surfactants has been done by spectroscopic techniques such as UV-visible and fluorescence. The results are discussed in the light of the use of gemini surfactants as promising drug delivery agents for phenothiazine drugs, and hence, improve their bioavailability.
    Energy, Resources and Environmental Technology
    Effect of endogenous hydrogen utilization on improved methane production in an integrated microbial electrolysis cell and anaerobic digestion: Employing catalyzed stainless steel mesh cathode
    Kiros Hagos, Chang Liu, Xiaohua Lu
    2018, 26(3):  574-582.  doi:10.1016/j.cjche.2017.08.005
    Abstract ( 1201 )   PDF (780KB) ( 88 )  
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    Improving the production of methane, while maintaining a significant level of process stability, is the main challenge in the anaerobic digestion process. Recently, microbial electrolysis cell (MEC) has become a promising method for CO2 reduction produced during anaerobic digestion (AD) and leads to minimize the cost of biogas upgrading technology. In this study, the MEC-AD coupled reactor was used to generate and utilize the endogenous hydrogen by employing biocompatible electrodeposited cobalt-phosphate as catalysts to improve the performance of stainless steel mesh and carbon cloth electrodes. In addition, the modified version of ADM1 model (ADM1da) was used to simulate the process. The result indicated that the MEC-AD coupled reactor can improve the CH4 yield and production rate significantly. The CH4 yield was enhanced with an average of 48% higher than the control. The CH4 production rate was also increased 1.65 times due to the utilization of endogenous hydrogen. The specific yield, flow rate, content of CH4, and pH value were the variables that the model was best at predicting (with indexes of agreement:0.960/0.941, 0.682/0.696, 0.881/0.865, and 0.764/0.743) of the process with SSmeshes 80/SS-meshes 200, respectively. Employing the catalyzed SS mesh cathode, in the MEC-AD coupled reactor, could be an effective approach to generate and facilitate the utilization of endogenous hydrogen in anaerobic digestion of CH4 production technology, which is a promising and feasible method to scale up to the industrial level.
    Indirect mineral carbonation of titanium-bearing blast furnace slag coupled with recovery of TiO2 and Al2O3
    Lin Wang, Weizao Liu, Jingpeng Hu, Qiang Liu, Hairong Yue, Bin Liang, Guoquan Zhang, Dongmei Luo, Heping Xie, Chun Li
    2018, 26(3):  583-592.  doi:10.1016/j.cjche.2017.06.012
    Abstract ( 994 )   PDF (1329KB) ( 95 )  
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    Large quantities of CO2 and blast furnace slag are discharged in the iron and steel industry. Mineral carbonation of blast furnace slag can offer substantial CO2 emission reduction and comprehensive utilization of the solid waste. This paper describes a novel route for indirect mineral carbonation of titanium-bearing blast furnace (TBBF) slag, in which the TBBF slag is roasted with recyclable (NH4)2SO4 (AS) at low temperatures and converted into the sulphates of various valuable metals, including calcium, magnesium, aluminium and titanium. High value added Ti-and Al-rich products can be obtained through stepwise precipitation of the leaching solution from the roasted slag. The NH3 produced during the roasting is used to capture CO2 from flue gases. The NH4HCO3 and (NH4)2CO3 thus obtained are used to carbonate the CaSO4-containing leaching residue and MgSO4-rich leaching solution, respectively. In this study, the process parameters and efficiency for the roasting, carbonation and Ti and Al recovery were investigated in detail. The results showed that the sulfation ratios of calcium, magnesium, titanium and aluminium reached 92.6%, 87% and 84.4%, respectively, after roasting at an AS-to-TBBF slag mass ratio of 2:1 and 350℃ for 2 h. The leaching solution was subjected to hydrolysis at 102℃ for 4 h with a Ti hydrolysis ratio of 95.7%and the purity of TiO2 in the calcined hydrolysate reached 98 wt%. 99.7% of aluminium in the Ti-depleted leaching solution was precipitated by using NH3. The carbonation products of Ca and Mg were CaCO3 and (NH4)2Mg(CO3)2·4H2O, respectively. The latter can be decomposed into MgCO3 at 100-200℃ with simultaneous recovery of the NH3 for reuse. In this process, approximately 82.1% of Ca and 84.2% of Mg in the TBBF slag were transformed into stable carbonates and the total CO2 sequestration capacity per ton of TBBF slag reached up to 239.7 kg. The TiO2 obtained can be used directly as an end product, while the Al-rich precipitate and the two carbonation products can act, respectively, as raw materials for electrolytic aluminium, cement and light magnesium carbonate production for the replacement of natural resources.
    Oxidative desulfurization of dibenzothiophene over Fe promoted Co-Mo/Al2O3 and Ni-Mo/Al2O3 catalysts using hydrogen peroxide and formic acid as oxidants
    Yaseen Muhammad, Ayesha Shoukat, Ata Ur Rahman, Haroon Ur Rashid, Waqas Ahmad
    2018, 26(3):  593-600.  doi:10.1016/j.cjche.2017.05.015
    Abstract ( 1171 )   PDF (1152KB) ( 180 )  
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    This work reports the enhancing effect of a highly cost effective and efficient metal, Fe, incorporation to Co or Ni based Mo/Al2O3 catalysts in the oxidative desulfurization (ODS) of dibenzothiophene (DBT) using H2O2 and formic acid as oxidants. The influence of operating parameters i.e. reaction time, catalyst dose, reaction temperature and oxidant amount on oxidation process was investigated. Results revealed that 99% DBT conversion was achieved at 60℃ and 150 min reaction time over Fe-Ni-Mo/Al2O3. Fe tremendously enhanced the ODS activity of Co or Ni based Mo/Al2O3 catalysts following the activity order:Fe-Ni-Mo/Al2O3 > Fe-Co-Mo/Al2O3 > Ni-Mo/Al2O3 > Co-Mo/Al2O3, while H2O2 exhibited higher oxidation activity than formic acid over all catalyst systems. Insight about the surface morphology and textural properties of fresh and spent catalysts were achieved using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, Atomic Absorption Spectroscopy (AAS) and BET surface area analysis, which helped in the interpretation of experimental data. The present study can be deemed as an effective approach on industrial level for ODS of fuel oils crediting to its high efficiency, low process/catalyst cost, safety and mild operating condition.
    Ozonation of o-phenylenediamine in the presence of hydrogen peroxide by high-gravity technology
    Moses Arowo, Zemeng Zhao, Guangjun Li, Guangwen Chu, Baochang Sun, Lei Shao
    2018, 26(3):  601-607.  doi:10.1016/j.cjche.2017.05.021
    Abstract ( 953 )   PDF (692KB) ( 21 )  
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    The study herein investigated the effectiveness of simultaneous use of ozone and hydrogen peroxide (O3/H2O2 process) to degrade o-phenylenediamine (o-PDA) in a simulated wastewater. A rotor-stator reactor (RSR) was employed to create a high-gravity environment in order to enhance ozone-liquid mass transfer rate and possibly improve the degradation rate of o-PDA. The degradation efficiency of o-PDA (η) as well as the overall gas-phase volumetric mass transfer coefficient (KGa) were determined under different operating conditions of H2O2 concentration, initial o-PDA concentration, temperature of reaction, initial pH and rotation speed of RSR in attempt to establish the optimal conditions. Chemical oxygen demand reduction rate (rCOD) of wastewater treated at a particular set of conditions was also analyzed. Additionally, the intermediate products of degradation were identified using a gas chromatography-mass spectrometer (GC/MS) to further evaluate the extent of o-PDA degradation as well as establish its possible degradation pathway. Results were validated by comparison with those of sole use of ozone (O3 process), and it was noted that η, KGa and rCOD achieved by O3/H2O2 process was 24.4%, 31.6% and 25.2% respectively higher than those of O3 process, indicating that H2O2 can greatly enhance ozonation of o-PDA. This work further demonstrates that an RSR can significantly intensify ozone-liquid mass transfer rate and thus provides a feasible intensification means for the ozonation of o-PDA as well as other recalcitrant organics.
    Variation of toxic pollutants emission during a feeding cycle from an updraft fixed bed gasifier for disposing rural solid waste
    Ming Lei, Jing Hai, Jiang Cheng, Jiawei Lu, Jieru Zhang, Tao You
    2018, 26(3):  608-613.  doi:10.1016/j.cjche.2017.07.019
    Abstract ( 846 )   PDF (724KB) ( 33 )  
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    The variation of toxic pollutants emission during a feeding cycle was examined by field monitoring from a batch feeding updraft fixed bed gasifier for disposing rural domestic solid waste. Results showed that the content of oxygen in flue gas gradually increased, while SO2 and HCl in flue gas decreased with time after feeding in a whole feeding cycle. Although large amount of CO was produced during the gasifying, low CO content in flue gas could be obtained after the heat treatment with an electric heating device. The distribution characteristics of dioxin congeners in flue gas indicted the re-synthesis of dioxins after flue gas heating, and the increase of oxygen promoted the synthesis of dioxins. The emission content of dioxins could meet the standard (0.1 ng I-TEQ·m-3, GB18458-2014) of China when the oxygen content was controlled below 8.3%. Hence, for a batch feeding gasifier, low oxygen condition should be offered by reducing air intake at the later stage of feeding cycle in order to decrease the re-synthesis of dioxins after the flue gas heating.
    Adsorptive potential of Acacia nilotica based adsorbent for chromium(VI) from an aqueous phase
    Raza Khalid, Zaheer Aslam, Aamir Abbas, Waqar Ahmad, Naveed Ramzan, Reyad Shawabkeh
    2018, 26(3):  614-622.  doi:10.1016/j.cjche.2017.08.017
    Abstract ( 1215 )   PDF (863KB) ( 48 )  
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    The objective of this research was to enhance adsorption capacity of Acacia nilotica (keekar) sawdust for the abatement of chromium bearing wastewater and to investigate the effect of process parameters on adsorption capacity. The sawdust was activated by acid wash and functionalized subsequently with formaldehyde. Functionalization of activated sawdust raised its chromium removal efficiency of almost 10% as compared to its adsorption removal efficiency of HCl treated sawdust in a batch adsorption study. Adsorption kinetic data provided better fitting with pseudo second order model. Maximum adsorption capacity calculated through the best fitting Langmuir model was 6.34 mg·g-1 and 8.2 mg·g-1 for HCl treated and formaldehyde functionalized sawdust adsorbents, respectively. The adsorption of Cr(VI) was endothermic when studied by varying temperature from 20℃ to 50℃ for both activated and functionalized adsorbents.
    Effect of heat flux and inlet temperature on the fouling characteristics of nanoparticles
    Jingtao Wang, Zhiming Xu, Zhimin Han, Yu Zhao
    2018, 26(3):  623-630.  doi:10.1016/j.cjche.2017.10.022
    Abstract ( 981 )   PDF (1152KB) ( 30 )  
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    In order to study the effect of heat flux and inlet temperature on the fouling characteristics of nanoparticles, and to further reveal the fouling mechanism for insights into proper operating conditions, γ-Al2O3/water suspensions were chosen as the subject of this research. The particulate fouling characteristics of γ-Al2O3/water suspensions on the surface of stainless steel have been experimentally studied by varying the heat flux and the inlet temperature under single-phase flow and subcooled-flow boiling conditions. The results show that in the condition of single-phase flow, the asymptotic value of fouling resistance decreases with increasing of heat flux and inlet temperature. The asymptotic value of fouling resistance under single-phase flow is much higher than for the subcooled-flow boiling condition. The effect of heat flux on the fouling resistance under the two flow states has an inverse relationship, and there exists a minimum value of fouling resistance between these two states. For subcooled-flow boiling, the asymptotic value of fouling resistance increases with increasing heat flux, whereas the effect on fouling resistance by the inlet temperature is negligible.
    Parametric study and effect of calcination and carbonation conditions on the CO2 capture performance of lithium orthosilicate sorbent
    Nurul Azrin Zubbri, Abdul Rahman Mohamed, Maedeh Mohammadi
    2018, 26(3):  631-641.  doi:10.1016/j.cjche.2017.09.015
    Abstract ( 1636 )   PDF (1084KB) ( 36 )  
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    The world is currently facing the challenges of global warming and climate change. Numerous efforts have been taken to mitigate CO2 emission, among which is the use of solid sorbents for CO2 capture. In this work, Li4SiO4 was synthesised via a sol-gel method using lithium nitrate (LiNO3) and tetraethylorthosilicate (SiC8H20O4) as precursors. A parametric study of Li:Si molar ratio (1-5), calcination temperature (600-800℃) and calcination time (1-8 h) were conducted during sorbent synthesis. Calcination temperature (700-800℃) and carbonation temperature (500-700℃) during CO2 sorption activity were also varied to confirm the optimum operating temperature. Sorbent with the highest CO2 sorption capacity was finally introduced to several cyclic tests to study the durability of the sorbent through 10 cycles of CO2 sorption-desorption test. The results showed that the calcination temperature of 800℃ and carbonation temperature of 700℃ were the best operating temperatures, with CO2 sorption capacity of 7.95 mmol CO2·(g sorbent)-1 (93% of the theoretical yield). Throughout the ten cyclic processes, CO2 sorption capacity of the sorbent had dropped approximately 16.2% from the first to the tenth cycle, which was a reasonable decline. Thus, it was concluded that Li4SiO4 is a potential CO2 solid sorbent for high temperature CO2 capture activity.
    Materials and Product Engineering
    Effects of nitrogen doping on surface-enhanced Raman scattering (SERS) performance of bicrystalline TiO2 nanofibres
    Haijuan Zhang, Rong An, Xinghong Ji, Yihui Dong, Fan Pan, Chang Liu, Xiaohua Lu
    2018, 26(3):  642-647.  doi:10.1016/j.cjche.2017.05.020
    Abstract ( 981 )   PDF (800KB) ( 78 )  
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    In this work, we successfully synthesized bicrystalline anatase/TiO2(B) nanofibre and used it as active substrate for surface-enhanced Raman scattering (SERS) applications. The bicrystalline structured TiO2 substrates provide additional charge transfer across the anatase-TiO2(B) interface and thus enhanced activity compared to the pure single crystalline phase. With an effort to further increase the sensitivity of SERS, nitrogen element was doped into bicrystalline anatase/TiO2(B) nanofibres (N-TiO2) and higher SERS enhancement was achieved. The nitrogen content was controlled by tuning the calcination temperature of titanate precursor at 500, 600 and 700℃, respectively. The sample calcined at 600℃ (NT600) acquires the highest percentage of nitrogen element due to its open pore structure that facilitates the diffusion of nitrogen during calcination. Raman intensity depends on the amount of nitrogen doping, thus NT600 exhibited the best SERS activity. The doped nitrogen in TiO2 facilitates the charge transfer between TiO2 and probing molecules and thus suppresses the electron-hole recombination. This work provides a new perspective on the design of efficient TiO2 SERS active substrate and is expected to be valuable for adsorbate detection on semiconductor surface.
    The combined effects of lysozyme and ascorbic acid on microstructure and properties of zein-based films
    Dongwei Wei, Weizhi Huo, Guangmeng Li, Qiuling Xie, Yanbin Jiang
    2018, 26(3):  648-656.  doi:10.1016/j.cjche.2017.07.005
    Abstract ( 878 )   PDF (829KB) ( 41 )  
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    Edible zein-based films containing lysozyme (LY) and ascorbic acid (AA) were developed in the presence of polyethylene glycol 400 (PEG 400), the combined effects of LY and AA on the microstructure, mechanical properties and release properties of developed zein films were investigated in detail. The results of microstructure characterization indicated that zein-based films became compact and smooth, and LY aggregates were well distributed in the zein matrix because of the simultaneous addition of LY and AA. The results of mechanical tests showed that because of the synergistic effects of LY and AA on zein film, elongation at break of zein-based film could be up to 138%, which was 34.5 times higher than that of zein control film. LY release tests showed that when the concentration of AA was less than 3.1 mg·cm-2, the release rate of LY significantly decreased by 33.7%, and the total release increased by 80.6%. While the release profiles of AA showed that the release rate and total release of AA from the films containing LY increased by approximately 68.9% and 61.7% than the films without LY. Good antioxidant and sustained antimicrobial activities were found for the developed zein films.
    Fabrication of chitosan microspheres for efficient adsorption of methyl orange
    Linlin Zhai, Zhishan Bai, Yong Zhu, Bingjie Wang, Wenqiang Luo
    2018, 26(3):  657-666.  doi:10.1016/j.cjche.2017.08.015
    Abstract ( 1215 )   PDF (868KB) ( 279 )  
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    In this article, morphology, structure and size controllable chitosan microspheres with high mechanical strength were synthesized by microfluidic technology combining chemical crosslinking and used as an adsorbent for methyl orange. The synthesized adsorbents were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and an Energy Dispersive Spectrometer (EDS). The effect of pH revealed that the adsorption process depended on pH and the pH variation of methyl orange solution after adsorption indicated that adsorption capacity was affected through the associated role of chitosan nature and pH variation. Experimental results suggested that the as-prepared chitosan microspheres were controlled within a narrow size distribution (coefficients of variation is 1.81%), whose adsorption capacity reached to 207 mg·g-1 and mechanical strength was suitable to resist forces. In addition, the adsorption isotherm was well fitted with the Langmuir model, and the adsorption kinetic was best described by the pseudo-second-order kinetic model. The high performance microfluidic-synthesized chitosan microspheres have promising potentials in the applications of removing dyes from wastewater.
    Synthesis of butterfly-like BiVO4/RGO nanocomposites and their photocatalytic activities
    Liangliang Zhang, Aolan Wang, Nan Zhu, Baochang Sun, Yan Liang, Wei Wu
    2018, 26(3):  667-674.  doi:10.1016/j.cjche.2017.09.007
    Abstract ( 972 )   PDF (839KB) ( 39 )  
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    A simple and high efficient method was proposed for the synthesis of uniform three dimensional (3D) BiVO4/reduced graphene oxide (RGO) nanocomposite photocatalyst by adopting the microwave assistant and using Bi (NO3)3·5H2O, graphene oxide (GO) and NH4VO3 as precursor. The as-obtained composites were well characterized with the aid of various techniques to study the morphology, structure, composition, optimal and electrical property. In the as-obtained composites, the GO sheets were fully reduced into RGO, and monoclinic structure BiVO4 crystallized completely into butterfly-like BiVO4 lamellas and well bonded with the RGO lamellas. The length and the width of the butterfly-like BiVO4 particle were about 1.5 μm, and the thickness of the flake was about 20 nm. Photocatalytic performances of BiVO4/RGO composite and pure BiVO4 particle have been evaluated by investigating the reduction of Cr(VI) ion-contained wastewater under simulated solar light irradiation, where the BiVO4/RGO composite displayed enhanced photocatalytic activity. It is found that the pseudo-first-order rate constants (k) for the photocatalytic reduction of Cr (VI) by BiVO4/RGO composite was about 4 times as high as that of the pure BiVO4. The present work suggested that the combination of BiVO4 and RGO displayed a remarkable synergistic effect, which led to enhanced photo-catalytic activity on Cr(VI) reduction.