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Table of Content
28 June 2017, Volume 25 Issue 6
    Clean coal technologies in Japan:A review
    Guoqing Guan
    2017, 25(6):  689-697.  doi:10.1016/j.cjche.2016.12.008
    Abstract ( 1792 )   PDF (816KB) ( 598 )  
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    Coal is the primary fossil fuel most used in the world for the electricity generation, iron making, and cement/concrete and chemical production. However, utilization of coal also results in emissions of CO2, SOx, NOx and other noxious compounds. The development of clean coal technology (CCT) is a main issue to maintain a clean environment. CCT in Japan is considered the highest level in the world. In this review, the developing CCTs in Japan including high efficiency combustion technologies, advanced gasification technologies, CO2 recovery and utilization technologies, and flue gas cleaning technologies are introduced and discussed. It is expected to provide some new view-of-points for CCT development.
    Breakage of drops and bubbles in a stirred tank:A review of experimental studies
    Basim O. Hasan
    2017, 25(6):  698-711.  doi:10.1016/j.cjche.2017.03.008
    Abstract ( 2102 )   PDF (645KB) ( 231 )  
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    The rate of breakage of drops and bubbles (fluid particles) in stirred systems is of great consequence on mass, heat, and momentum transport phenomena. Therefore, over the years, the topic has gained a considerable attention from the researchers to study and characterize this phenomenon. In present work, the experimental studies of breakage phenomenon in a stirred tank in the last four decades were reviewed. The review highlighted the investigated experimental conditions and the major findings concerning the breakage mechanism and the effect of operating conditions. The discrepancy and contradictions of the outcomes of those studies were specified and discussed. Experimental observations and conclusions concerning the breakage characterization parameters, such as deformation, breakage probability, breakage time, and breakage location were presented and commented on. Possible future refinements and prospective were recommended. The review indicated that there are clear discrepancies and contradictions between previous studies regarding the effect of some operating parameters and the values of breakage time, breakage probability, number of daughter particles, and breakage location relative to the impeller. In addition, there are still many scientific gaps that need to be studied and characterized in future by overcoming specific experimental difficulties and uncertainties.
    Fluid Dynamics and Transport Phenomena
    Thermophoresis effects on gas-particle phases flow behaviors in entrained flow coal gasifier using Eulerian model
    Chao Dai, Fan Gu
    2017, 25(6):  712-721.  doi:10.1016/j.cjche.2016.11.016
    Abstract ( 1109 )   PDF (1818KB) ( 97 )  
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    A numerical model based on the Eulerian-Eulerian two-fluid approach is used to simulate the gasification of coal char inside an entrained flow gasifier. In this model, effects of thermophoresis of coal char particles are thoroughly investigated. The thermophoresis is due to the gas temperature gradient caused by absorpted heat of coal char gasification. This work, firstly, calculates the gas temperature gradient and thermophoretic force at 1100℃,1200℃,1300℃ and 1400℃ wall temperatures. Then, the changes of particle volume fraction and velocity in the gasifier are studied in the simulation with thermophoresis or not. The results indicate that considering the particle thermophoresis has some effects on the calculation of particle volume fraction in the gasifier, especially at wall temperature of 1400℃, and the maximum particle volume fraction variance ratio reaches up to 1.38% on wall surface of the gasifier. These effects are mainly caused by large gas temperature gradient along the radial direction of the gasifier. For the particle velocity, the changes are small but can be observable along radial direction of the gasifier, which has good agreement with the distributions of radial gas temperature gradient and thermophoretic force. These changes above may have certain effects on gasification reaction rates in this Eulerian model. So the change of gasification reaction rates in the simulation with thermophoresis or not is studied finally.
    Optimization of the fuel rod's arrangement cooled by turbulent nanofluids flow in pressurized water reactor (PWR)
    M. Hatami, M. J. Z. Ganji, I. Sohrabiasl, D. Jing
    2017, 25(6):  722-731.  doi:10.1016/j.cjche.2016.10.022
    Abstract ( 1144 )   PDF (1073KB) ( 97 )  
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    In this paper, response surface methodology (RSM) based on central composite design (CCD) is applied to obtain an optimization design for the fuel rod's diameter and distance cooled by turbulent Al2O3-water nanofluid for a typical pressurized water reactor (PWR). Fuel rods and nanofluid flow between them are simulated 3D using computational fluid dynamics (CFD) by ANSYS-FLUNET package software. The RNG k-ε model is used to simulate turbulent nanofluid flow between the rods. The effect of different nanoparticles concentration is also investigated on the Nusselt number from heat transfer efficiency view point. Results reveal that when distance parameter (a) is in the minimum level and diameter parameter (r) is in the maximum possible level, cooling the rods will be better due to higher Nusselt number in this situation. Also, using the different nanoparticles on the cooling process confirms that Al2O3 averagely 17% and TiO2 10% improve the Nusselt numbers.
    Computational fluid dynamics simulation of a novel bioreactor for sophorolipid production
    Xiaoqiang Jia, Lin Qi, Yaguang Zhang, Xue Yang, Hongna Wang, Fanglong Zhao, Wenyu Lu
    2017, 25(6):  732-740.  doi:10.1016/j.cjche.2016.09.014
    Abstract ( 1370 )   PDF (1031KB) ( 160 )  
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    This paper describes three-dimensional computational fluid dynamics (CFD) simulations of gas-liquid flow in a novel laboratory-scale bioreactor contained dual ventilation-pipe and double sieve-plate bioreactor (DVDSB) used for sophorolipid (SL) production.To evaluate the role of hydrodynamics in reactor design,the comparisons between conventional fed-batch fermenter and DVDSB on the hydrodynamic behavior are predicted by the CFD methods.Important hydrodynamic parameters of the gas-liquid two-phase system such as the liquid phase velocity field,turbulent kinetic energy and volume-averaged overall and time-averaged local gas holdups were simulated and analyzed in detail.The numerical results were also validated by experimental measurements of overall gas holdups.The yield of sophorolipids was significantly improved to 484 g·L-1 with a 320 h fermentation period in the new reactor.
    Fouling of WO3 nanoparticle-incorporated PSf membranes in ultrafiltration of landfill leachate and dairy a combined wastewaters:An investigation using model
    Majid Peyravi, Mohsen Jahanshahi, Soodabeh Khalili
    2017, 25(6):  741-751.  doi:10.1016/j.cjche.2016.12.001
    Abstract ( 1372 )   PDF (700KB) ( 142 )  
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    As fouling has always been a major drawback of membrane technology, qualitative and quantitative understanding of membrane fouling mechanisms therefore becomes vital in order to help push membrane separation technologies forward. In this study, firstly, self-cleaning Polysulfone (PSf) membranes were synthesized by incorporation of WO3 nanoparticles (0-2 wt%) and subsequent UV irradiation for efficient ultrafiltration (UF) of landfill leachate and dairy wastewater. The membrane surface properties were characterized by scanning electron microscopy (SEM) and contact angle analysis. It was found that UV-irradiated membranes exhibited higher percent COD removals due to the hydrophilicity and photocatalytic properties of nano-WO3. Subsequently, in order to analyze the fouling behavior of the membranes, a set of experimental data from cross-flow ultrafiltration of municipal landfill leachate and industrial dairy wastewater at 25℃ was obtained. A new model of membrane fouling was proposed based on a resistance in series concept and was fitted well with all experimental data sets. Almost all relative errors of prediction provided by the proposed model were less than 2.5%. In addition, it was revealed that this newly-developed model exhibited smooth transition between the common successive twostep pore blockage-cake filtration phenomena and thus eliminates the need to use separate equations for different mechanisms.
    Separation Science and Engineering
    Graphene oxide membranes supported on the ceramic hollow fibre for efficient H2 recovery
    Kang Huang, Jianwei Yuan, Guoshun Shen, Gongping Liu, Wanqin Jin
    2017, 25(6):  752-759.  doi:10.1016/j.cjche.2016.11.010
    Abstract ( 1384 )   PDF (1063KB) ( 106 )  
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    The special channels and intrinsic defects within GO laminates make it a very potential candidate for gas separation in recent years. Herein, the gas separation performance of GO membranes prepared on the surface of ceramic α-Al2O3 hollow fibre was investigated systematically. The microstructures of ceramic hollow fibre supported GO membranes were optimized by adjusting operation conditions. And, the GO membrane fabricated at 30 min exhibited great promising H2 recovery ability from H2/CO2 mixture. At room temperature, the H2 permeance was over 1.00×10-7 mol·m-2·s-1·Pa-1 for both single gas and binary mixture. The corresponding ideal selectivity and mixture separation factor reached around 15 and 10, respectively. In addition, humility, operation temperature, H2 concentration in the feed and the reproducibility were also studied in this work.
    The separation and recovery of copper(Ⅱ), nickel(Ⅱ), cobalt(Ⅱ), zinc(Ⅱ), and cadmium(Ⅱ) in a sulfate-based solution using a mixture of Versatic 10 acid and Mextral 984H
    Yinxuan Qiu, Limei Yang, Songtao Huang, Zhongguang Ji, Yan Li
    2017, 25(6):  760-767.  doi:10.1016/j.cjche.2016.10.013
    Abstract ( 1450 )   PDF (741KB) ( 283 )  
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    We studied the separation and recovery of copper(Ⅱ), nickel(Ⅱ), cobalt(Ⅱ), zinc(Ⅱ), and cadmium(Ⅱ) from magnesium and calcium, using synergistic solvent extraction (SSX) in a typical hydrometallurgical waste solution. A mixture of Versatic 10 acid and Mextral 984H, diluted with Mextral DT100, was used to obtain fundamental data on pH and distribution isotherms, as well as the kinetics of extraction and stripping. We also investigated the main effects and interactions of common solvent extraction factors:the extraction pH at equilibrium, the temperature, and the extractant concentration. The synergistic effect for extracting metals was confirmed. The results showed that the addition of Mextral 984H enhanced the separation factors of copper, nickel, cobalt, zinc, and cadmium over magnesium and calcium. Compared with Versatic 10 acid alone, for a mixture of 0.5 mol·L-1 Versatic 10 acid/0.5 mol·L-1 Mextral 984H, ΔpH50 values of copper, nickel, cobalt, zinc, and cadmium were found to be >2.0, 3.30, 2.85, 0.95, and 1.32 pH units, respectively. The ΔpH50(Zn-Mg) and ΔpH50(Zn-Ca) values were 3.27 and 2.25, respectively, indicating easy separation and recovery of copper, nickel, zinc, cobalt, and cadmium. The extraction and stripping of copper, cobalt, zinc, and cadmium were fast, with 90% of the metal transferred in 2 min. We next studied whether the metals could be stripped from the extracted liquid selectively in sequence, by using sulfuric acid at different concentrations. The influence of the molecular structure of the oxime and carboxylic acid components upon the synergistic effects was identified by numerical analysis. Excellent separation of copper, nickel, cobalt, and zinc over magnesium and calcium was achieved with this synergistic solvent extraction system.
    Reversible adsorption of metalworking fluids (MWFs) on Cu-BTC metal organic framework
    Kwannapat Sorachoti, Bhuckchanya Pangkumhang, Visanu Tanboonchuy, Sarttrawut Tulaphol, Nurak Grisdanurak
    2017, 25(6):  768-774.  doi:10.1016/j.cjche.2016.11.011
    Abstract ( 1496 )   PDF (616KB) ( 158 )  
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    Metalworking fluids (MWFs) are classified as hazardous substances. Due to the characteristics of the stable oil-water emulsions, it requires more costly and complicate treatment techniques to remove oil from spent MWFs. Metal organic frameworks (MOFs) are a porous network material used to remove contaminants from environment. One of the most prominent of MOFs is HKUST-1 or Cu-BTC. In this study, the Cu-BTCs were prepared by solvothermal method in various conditions and used as absorbent for removing oil micelles in MWF emulsion. The particle size of all synthesized Cu-BTCs ranged from ≈80 to 400 nm. The ability of all synthesized Cu-BTCs to remove oil micelle was greater than 95% in 60 min, while the capacity of GAC was obtained the result for only 6.8%. The maximum adsorption capacity (qmax) of oil micelles on Cu-BTCs was 1666.7 mg·g-1. The highest removal capacity of oil micelles in MWF emulsion is greater than 99% in 24 h by using Cu-BTCs washed with either butanol or ethanol.
    Adsorption removal of o-nitrophenol and p-nitrophenol from wastewater by metal-organic framework Cr-BDC
    Jianhua Chen, Xue Sun, Lijing Lin, Xinfei Dong, Yasan He
    2017, 25(6):  775-781.  doi:10.1016/j.cjche.2016.10.014
    Abstract ( 1669 )   PDF (493KB) ( 258 )  
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    In the present paper, a metal-organic framework Cr-BDC was prepared and used as adsorbent for adsorption of o-nitrophenol (ONP) and p-nitrophenol (PNP) from aqueous solutions. Cr-BDC was characterized by scanning electron microscopy, transmission electron microscope, X-ray diffraction and BET methods. The results indicate that Cr-BDC gets a very large specific surface area of 4128 m2·g-1 and pore sizes are concentrated in 1 nm, which is a benefit for using for wastewater treatment. The influences of the adsorption conditions, such as temperature, solution concentration, adsorption time and reusability on adsorption performance were investigated. Cr-BDC exhibited an encouraging uptake capacity of 310.0 mg·g-1 for ONP, and adsorption capacity of Cr-BDC for ONP is significantly higher than that for PNP under suitable adsorption conditions. The characterizations of adsorption process were examined with the Lagergren pseudo-first-order, the pseudo-second-order kinetic model, and the intra-particular diffusion model. Kinetics experiments indicated that the pseudo-second-order model displayed the best correlation with adsorption kinetics data. Furthermore, our adsorption equilibrium data could be better described by the Freundlich equation. The results indicate that the as-prepared Cr-BDC is promising for use as an effective and economical adsorbent for ONP removal.
    Influence of monovalent cations and CuO nanoparticles on X-nanozeolite in uranium anionic species separation from contaminated drinking water
    H. R. Shakur, Kh. Rezaee Ebrahim Saraee, M. R. Abdi, G. Azimi
    2017, 25(6):  782-792.  doi:10.1016/j.cjche.2016.11.012
    Abstract ( 1317 )   PDF (874KB) ( 137 )  
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    The main purpose of this work was the modification of NaX nanozeolite using copper oxide nanoparticles and various monovalent cations such as K+, Cs+, and Ag+ in order to make the negatively charged zeolite surface accessible for anionic forms of uranium which are the most dominant species of uranium in the contaminated radioactive waters at natural pH. Various methods such as the X-ray fluorescence (XRF), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and atomic absorption spectroscopy (AAS) were used to characterize the final synthesized absorbents. Batch technique was used to study the adsorption behavior of uranium ions from polluted drinking water by NaX nanozeolite and its modified forms. In order to better understand the performance of them, the results were compared with those that were obtained for synthesizing bulk NaX zeolite and Na-form of clinoptilolite natural zeolite. Preliminary results indicated that uranium sorption increased as the loading level of CuO nanoparticles on NaX nanozeolite increased from 2.1 wt% to 11.2 wt%. In addition, from the obtained data, an increase in uranium removal efficiency resulted as charge/ionic radius ratio of exchanged cation decreased. Also, the effect of contact time, solid-liquid ratio, initial concentration and temperature on the adsorption process was studied. It is worth mentioning that, in this study, the sorption of uranium was performed under natural conditions of pH and the presence of competing cations and anions which are available in drinking waters.
    Process Systems Engineering and Process Safety
    Energy efficiency evaluation based on DEA integrated factor analysis in ethylene production
    Shixin Gong, Cheng Shao, Li Zhu
    2017, 25(6):  793-799.  doi:10.1016/j.cjche.2016.10.023
    Abstract ( 1708 )   PDF (566KB) ( 150 )  
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    Energy efficiency evaluation plays an important role in energy efficiency improvement of the ethylene production. It is observed from the actual production data that the ethylene production energy efficiency often varies with the complex production working conditions. In the favored methods for energy efficiency evaluation, DEA models may show poor resolution when directly used to evaluate the efficiency values. Therefore, a new energy efficiency evaluation method for ethylene production is proposed based on DEA integrated factor analysis with respect to operation classification. Three key factors, including raw material composition, cracking depth and load rate, are taken into account in determining the production working conditions by means of k-means algorithm. Based on the multi-working conditions mode the energy efficiency evaluation of the ethylene production is made by using DEA model, where the most related energy data are screened by factor analysis. Furthermore, the supporting decision of energy efficiency improvement is provided to the operators. The accuracy and effectiveness of the proposed method are illustrated by applying in a practical ethylene production, which gives more effective energy efficiency evaluation in the complicated working conditions of ethylene production with declined dimension of input indicators.
    NLO response of derivatives of benzene, stilbene and diphenylacetylene:MP2 and DFT calculations
    A. M. Elhorri, M. Zouaoui-Rabah
    2017, 25(6):  800-808.  doi:10.1016/j.cjche.2016.09.001
    Abstract ( 1093 )  
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    MP2 method and different functionals such as M06-HF, M06-2X, CAM-B3LYP, PBE0, B3LYP and M06L incorporating different XC amounts were used to calculate the static first hyperpolarizabilies β(0) of eight molecules which are derivatives of benzene, stilbene and diphenylacetylene. The values were then compared to the experimental ones. The M06-2X functional was then selected for further calculations. NBO calculations were also performed to define the intramolecular charge transfer in each molecule. TD-DFT calculations were performed taking into account the solvent effect using the IEF-PCM formalism. Some parameters characterizing the vertical transitions such as the wavelength of the maximum absorption λmax were compared to the experimental ones. Finally, solvation Gibbs free enthalpy ΔGsolv values have also been examined in order to determine which the specific solvent for a given molecule is.
    Chemical Engineering Thermodynamics
    Experimental determination of solubilities and supersolubilities of 2,2',4,4',6,6'-hexanitrostilbene in different organic solvents
    Lizhen Chen, Liang Song, Yupeng Gao, Aipeng Zhu, Duanlin Cao
    2017, 25(6):  809-814.  doi:10.1016/j.cjche.2016.09.004
    Abstract ( 1432 )   PDF (292KB) ( 130 )  
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    The laser monitor technique was used to determine solubilities and supersolubilities of HNS in N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, N-methyl-2-pyrrolidone and 1,4-butyrolactone. The experimental solubility values were correlated with λh equation, modified Apelblat equation and NRTL model. Furthermore, the dissolution enthalpy, dissolution entropy and the Gibbs energy of HNS were calculated by the experimental data. The results show that the solubilities of HNS in the above solvents increase with the increasing temperature. Besides, at the same temperature, the order of solubility is N-methyl-2-pyrrolidone > dimethyl sulfoxide > N,N-dimethylformamide > 1,4-butyrolactone > acetonitrile. The temperature dependence of predicted solubility is in agreement with the experimental data.
    Energy, Resources and Environmental Technology
    Chemical composition and structure characterization of distillation residues of middle-temperature coal tar
    Zhihui Sun, Weihong Zhang
    2017, 25(6):  815-820.  doi:10.1016/j.cjche.2016.12.007
    Abstract ( 1585 )   PDF (552KB) ( 171 )  
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    The distillation residues of middle-temperature coal tar (DRMCT) were separated into saturate, aromatic, resin and asphaltene fractions by using the combination of solvent extraction and column chromatography separation. The isolated four fractions have been further characterized through the combination of elemental analysis, Fourier transform infrared (FTIR) spectra, proton nuclear magnetic resonance spectrum (1H NMR) and molecular weight analysis. The analysis results confirm the view that the saturate fraction from DRMCT was mainly composed of long-chain alkanes and almost all of the heteroatoms (S, N and O) were existed in aromatic structures. The asphaltene fraction had the highest molecular weight, the most amount of heteroatom (especially oxygen) and was the most condensed with shortest alkyl side chains among all the fractions. In addition, for the heavier components, the resin and asphaltene fractions from DRMCT contained lower ratio of H/C, lower molecular weight and higher aromaticity degree when compared with crude oils.
    Materials and Product Engineering
    Preparation of synthetic rutile via selective sulfation of ilmenite with (NH4)2SO4 followed by targeted removal of impurities
    Weizao Liu, Xiaomei Wang, Zhenpu Lu, Hairong Yue, Bin Liang, Li Lü, Chun Li
    2017, 25(6):  821-828.  doi:10.1016/j.cjche.2016.10.007
    Abstract ( 1148 )   PDF (755KB) ( 167 )  
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    This paper describes a novel, facile chemical pathway for preparing synthetic rutile from ilmenite. The pathway consists of two primary units, i.e., selectively sulfating ilmenite, which was realized via roasting ilmenite with (NH4)2SO4 followed by selective thermal decomposition of the sulfated ilmenite, and targeted leaching of the impurities. The effects of the process parameters were systematically investigated. The results showed that the optimum sulfation conditions were a mass ratio of (NH4)2SO4 to ilmenite of 14, temperature of 360℃, and time of 120 min with a sulfation ratio of~95%. The optimum thermal decomposition conditions were 480℃ in N2 atmosphere, and nearly all TiOSO4 were decomposed with co-decomposition of FeSO4 of 23%. For acid leaching, the optimum conditions were 2.5 wt% HCl, 98℃ and 120 min. Under those conditions, 94.2% iron was removed with a TiO2 dissolution loss <1%. For alkali leaching, 67% SiO2 was removed in 5 wt% NaOH at 102℃ for 1 h. A synthetic rutile with a TiO2 content >92 wt% and total MgO + CaO <1.5 wt% was obtained. Based on these results, a schematic flowsheet was proposed. Additionally, it was found that the decomposition of FeSO4 mixed with TiOSO4 under N2 was inhibited due to its oxidation to a higher thermal stability Fe2(SO4)3 by oxygen emitted from the decomposition of TiOSO4. At the same time, TiOSO4 decomposition was promoted due to the immediate in situ consumption of oxygen by FeSO4. The synergetic effect might be responsible for the enhanced selectivity of sulfated ilmenite thermal decomposition.