Please wait a minute...
[an error occurred while processing this directive]
Table of Content
28 August 2015, Volume 23 Issue 8
    A Reynolds mass flux model for gas separation process simulation: II. Application to adsorption on activated carbon in a packed column
    Wenbin Li, Kuotsung Yu, Xigang Yuan, Botan Liu
    2015, 23(8):  1245-1255.  doi:10.1016/j.cjche.2015.01.012
    Abstract ( 2122 )   PDF (636KB) ( 80 )  
    References | Related Articles | Metrics
    Simulations of adsorption process using the Reynolds mass flux model described in Part I of these serial articles are presented. The object of the simulation is the methylene chloride adsorption in a packed column (0.041mid, packed with spherical activated carbon up to a length of 0.2 m). With the Reynolds mass flux model, breakthrough/regeneration curves, concentration and temperature as well as the velocity distributions can be obtained. The simulated results are compared with the experimental data reported in the literature and satisfactory agreement is found both in breakthrough/regeneration curves and temperature curves. Moreover, the anisotropic turbulent mass diffusion is characterized and discussed.
    Turbulent forced convection in a heat exchanger square channel with wavy-ribs vortex generator
    Amnart Boonloi, Withada Jedsadaratanachai
    2015, 23(8):  1256-1265.  doi:10.1016/j.cjche.2015.04.001
    Abstract ( 2097 )   PDF (3499KB) ( 83 )  
    References | Related Articles | Metrics
    Turbulent forced convective heat transfer and flow configurations in a square channel with wavy-ribs inserted diagonally are examined numerically. The influences of the 30° and 45° flowattack angles forwavy-ribs, blockage ratio, RB=b/H=0.05-0.25with single pitch ratio, RP=P/H=1 are investigated for the Reynolds number based on the hydraulic diameter of the square channel, Re=3000-20000. The use of the wavy-ribs, which inserted diagonal in the square channel, is aimed to help to improve the thermal performance in heat exchange systems. The finite volume method and SIMPLE algorithm are applied to the present numerical simulation. The results are presented on the periodic flow and heat transfer profiles, flow configurations, heat transfer characteristics and the performance evaluations. The mathematical results reveal that the use of wavy-ribs leads to a higher heat transfer rate and friction loss over the smooth channel. The heat transfer enhancements are around 1.97-5.14 and 2.04-5.27 times over the smooth channel for 30° and 45° attack angles, respectively. However, the corresponding friction loss values for 30° and 45° are around 4.26-86.55 and 5.03-97.98 times higher than the smooth square channel, respectively. The optimumthermal enhancement factor on both cases is found at RB=0.10 and the lowest Reynolds number, Re=3000, to be about 1.47 and 1.52, respectively, for 30° and 45° wavy-ribs.
    Optimization of natural convection heat transfer of Newtonian nanofluids in a cylindrical enclosure
    Hamid Moradi, Bahamin Bazooyar, Ahmad Moheb, Seyed Gholamreza Etemad
    2015, 23(8):  1266-1274.  doi:10.1016/j.cjche.2015.04.002
    Abstract ( 2910 )   PDF (6440KB) ( 73 )  
    References | Related Articles | Metrics
    This study characterizes and optimizes natural convection heat transfer of two Newtonian Al2O3 and TiO2/water nanofluids in a cylindrical enclosure. Nusselt number (Nu) of nanofluids in relation to Rayleigh number (Ra) for different concentrations of nanofluids is investigated at different configurations and orientations of the enclosure. Results show that adding nanoparticles towater has a negligible or even adverse influence upon natural convection heat transfer of water: only a slight increase in natural convection heat transfer of Al2O3/water is observed, while natural convection heat transfer for TiO2/water nanofluid is inferior to that for the base fluid. Results also reveal that at low Ra, the likelihood of enhancement in natural convection heat transfer ismore than at high Ra: at low Ra, inclination angle, aspect ratio of the enclosure and nanoparticle concentration influence natural convection heat transfer more pronouncedly than that in high Ra.
    Gas adsorption in shaped zeolitic imidazolate framework-8
    Jiqin Zhu, Lu Jiang, Chengna Dai, Na Yang, Zhigang Lei
    2015, 23(8):  1275-1282.  doi:10.1016/j.cjche.2015.01.015
    Abstract ( 2551 )   PDF (6190KB) ( 74 )  
    References | Related Articles | Metrics
    Zeolitic imidazolate framework-8 (ZIF-8) was prepared through a solve-thermal reactionmethod and then shaped using different additives. The influence of the shaping conditions on the microstructure of the shaped samples was characterized by the XRD, BET, and SEM techniques. The results demonstrate that the compressive strength of the various shaped tablets is greatly increased and capable of meeting the industrial requirements compared to the unshaped ZIF-8 and that the loss rate of specific surface areas was maintained at 10% after the addition of 10%(by mass) binder and 10%(by mass) solvent. The adsorption isotherms of CO2, CH4, C3H8, and C3H6 on powdery ZIF-8 and the shaped tablets (T-shaped ZIF-8, C-shaped ZIF-8, and N-shaped ZIF-8) were determined through volumetric measurements under different pressures and temperatures (298.2, 323.2, and 348.2 K). The adsorption capacities of the gases on both the ZIF-8 powder and the shaped tablets follow the order C3H6 > C3H8 > CO2 > CH4. Furthermore, the results show that the adsorption capacities of the gases on the shaped tablets are lower by approximately 10%-20% than those on the powdery ZIF-8. In fact, the adsorption equilibrium isotherms for CO2, CH4, C3H8, and C3H6 on both powdery and shaped ZIF-8 can be well described by the Langmuir equation.
    Preparation of pH-responsive membranes with amphiphilic copolymers by surface segregation method
    Yanlei Su, Yuan Liu, Xueting Zhao, Yafei Li, Zhongyi Jiang
    2015, 23(8):  1283-1290.  doi:10.1016/j.cjche.2015.05.013
    Abstract ( 2156 )   PDF (949KB) ( 77 )  
    References | Related Articles | Metrics
    Novel pH-responsive membranes were prepared by blending pH-responsive amphiphilic copolymers with polyethersulfone (PES) via a nonsolvent-induced phase separation (NIPS) technique. The amphiphilic copolymers bearing Pluronic F127 and poly(methacrylic acid) (PMAA) segments, abbreviated as PMAAn-F127-PMAAn, were synthesized by free radical polymerization. The physical and chemical properties of the blend membranes were evaluated by scanning electronmicroscopy (SEM), Fourier transform infrared (FTIR) spectrum, water contact angle, Zeta potential and X-ray photoelectron spectroscopy (XPS). The enrichment of hydrophilic PMAA segments on the membrane surfaces was attributed to surface segregation during the membrane preparation process. The blend membranes had significant pH-responsive properties due to the conformational changes of surface-segregated PMAA segments under different pH values of feed solutions. Fluxes of the blend membranes were larger at lowpH values of feed solutions than that at high pH values. The pH-responsive ability of themembranes was enhanced with the increase of the degree of PMAA near-surface coverage.
    Computational exploration of H2S/CH4 mixture separation using acid-functionalized UiO-66(Zr) membrane and composites
    Shumeng Wang, Dong Wu, Hongliang Huang, Qingyuan Yang, Minman Tong, Dahuan Liu, Chongli Zhong
    2015, 23(8):  1291-1299.  doi:10.1016/j.cjche.2015.04.017
    Abstract ( 3288 )   PDF (2117KB) ( 59 )  
    References | Related Articles | Metrics
    A computational study was firstly performed in this work to examine the applicability of an acid-functionalized metal-organic framework (MOF), UiO-66(Zr)-(COOH)2, in membrane-based H2S/CH4 separation. The results showthat this MOF could be potentially interesting when being used as the pure membrane material for the separation of the mixturewith low H2S concentration. Further, the performance of 10 different mixed matrixmembranes (MMMs) on the basis of the MOF was predicted by combing the molecular simulation data and the Maxwell permeationmodel. The results indicate that using this MOF as filler particles in MMMs can significantly enhance the permeation performance of pure polymers. The findings obtained in this work may be helpful in facilitating the application of this promising MOF for practical desulfurization process of fuel gas.
    Gas separation using sol-gel derived microporous zirconia membranes with high hydrothermal stability
    Li Li, Hong Qi
    2015, 23(8):  1300-1306.  doi:10.1016/j.cjche.2015.05.005
    Abstract ( 2434 )   PDF (1055KB) ( 123 )  
    References | Related Articles | Metrics
    A microporous zirconia membrane with hydrogen permeance about 5×10-8 mol·m-2·s-1·Pa-1, H2/CO2 permselectivity of ca. 14, and excellent hydrothermal stability under steam pressure of 100 kPa was fabricated via polymeric sol-gel process. The effect of calcination temperature on single gas permeance of sol-gel derived zirconia membranes was investigated. Zirconia membranes calcined at 350℃ and 400℃ showed similar single gas permeance, with permselectivities of hydrogen towards other gases, such as oxygen, nitrogen, methane, and sulfur hexafluoride, around Knudsen values. A much lower CO2 permeance (3.7×10-9 mol·m-2·s-1·Pa-1) was observed due to the interaction between CO2 molecules and pore wall of membrane. Higher calcination temperature, 500℃, led to the formation of mesoporous structure and, hence, the membrane lost itsmolecular sieving property towards hydrogen and carbon dioxide. The stability of zirconia membrane in the presence of hot steam was also investigated. Exposed to 100 kPa steam for 400 h, the membrane performance kept unchanged in comparison with freshly prepared one, with hydrogen and carbon dioxide permeances of 4.7×10-8 and~3×10-9 mol·m-2·s-1·Pa-1, respectively. Both H2 and CO2 permeances of the zirconia membrane decreased with exposure time to 100 kPa steam. With a total exposure time of 1250 h, the membrane presented hydrogen permeance of 2.4×10-8 mol·m-2·s-1·Pa-1 and H2/CO2 permselectivity of 28, indicating that the membrane retains its microporous structure.
    Green synthesis of nickel nanoparticles using Ocimum sanctum and their application in dye and pollutant adsorption
    Chitra Jeyaraj Pandian, Rameshthangam Palanivel, Solairaj Dhananasekaran
    2015, 23(8):  1307-1315.  doi:10.1016/j.cjche.2015.05.012
    Abstract ( 4151 )   PDF (1381KB) ( 938 )  
    References | Related Articles | Metrics
    Nickel nanoparticles as an eco-friendly adsorbent was biosynthesized using Ocimum sanctum leaf extract. The physiochemical properties of green synthesized nickel nanoparticles (NiGs) were characterized by UV-Vis spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). NiGs were used as adsorbent for the removal of dyes such as crystal violet (CV), eosin Y (EY), orange II (OR) and anionic pollutant nitrate (NO3-), sulfate (SO42-) fromaqueous solution. Adsorption capacity of NiGswas examined in batchmodes at different pH, contact time, NiG dosage, initial dye and pollutant concentration. The adsorption process was pH dependent and the adsorption capacity increased with increase in contact time and with that of NiG dosage,whereas the adsorption capacity decreased at higher concentrations of dyes and pollutants. Maximum percentage removal of dyes and pollutants were observed at 40, 20, 30, 10 and 10 mg·L-1 initial concentration of CV, EY, OR, NO3- and SO42- respectively. The maximum adsorption capacities in Langmuir isotherm were found to be 0.454, 0.615, 0.273, 0.795 and 0.645 mg·g-1 at pH 8, 3, 3, 7 and 7 for CV, EY, OR, NO3- and SO42- respectively. The higher coefficients of correlation in Langmuir isotherm suggested monolayer adsorption. The mean energies (E), 2.23, 3.53, 2.50, 5.00 and 3.16 kJ·mol-1 for CV, EY, OR, NO3- and SO42- respectively, calculated from the Dubinin-Radushkevich isotherm showed physical adsorption of adsorbate onto NiGs. Adsorption kinetics data was better fitted to pseudo-second-order kinetics with R2 > 0.870 for all dyes and pollutants. NiGs were found to be an effective adsorbent for the removal of dyes and pollutants from aqueous solution and can be applied to treat textile and tannery effluents.
    Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor
    Masoud Hasany, Mohammad Malakootikhah, Vahid Rahmanian, Soheila Yaghmaei
    2015, 23(8):  1316-1325.  doi:10.1016/j.cjche.2015.05.006
    Abstract ( 2461 )   PDF (1758KB) ( 97 )  
    References | Related Articles | Metrics
    A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibriumto ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogenation method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor performance in terms of high conversions and significant energy saving. It was also established that the sweep gas velocity in the shell side of the reactor is one of the most important factors in the effectiveness of the reactor.
    Enhanced performance of g-C3N4/TiO2 photocatalysts for degradation of organic pollutants under visible light
    Gaixue Song, Zhenyu Chu, Wanqin Jin, Hongqi Sun
    2015, 23(8):  1326-1334.  doi:10.1016/j.cjche.2015.05.003
    Abstract ( 3679 )   PDF (3045KB) ( 199 )  
    References | Related Articles | Metrics
    Photocatalytic degradation is one of the most promising remediation technologies in terms of advanced oxidation processes (AOPs) for water treatment. In this study, novel graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2) composites were synthesized by a facile sonication method. The physicochemical properties of the photocatalystwith different mass ratios of g-C3N4 to TiO2were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), N2 sorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and UV-vis DRS. The photocatalytic performances were evaluated by degradation of methylene blue. Itwas found that g-C3N4/TiO2with amass ratio of 1.5:1 exhibited the best degradation performance. Under UV, the degradation rate of g-C3N4/TiO2 was 6.92 and 2.65 times higher than g-C3N4 and TiO2, respectively. While under visible light, the enhancement factors became 9.27 (to g-C3N4) and 7.03 (to TiO2). The improved photocatalytic activity was ascribed to the interfacial charge transfer between g-C3N4 and TiO2. This work suggests that hybridization can produce promising solar materials for environmental remediation.
    Reaction kinetics of isopropyl palmitate synthesis
    Lili Fu, Yinge Bai, Gaozhi Lü, Denggao Jiang
    2015, 23(8):  1335-1339.  doi:10.1016/j.cjche.2015.05.004
    Abstract ( 2918 )   PDF (5239KB) ( 120 )  
    References | Related Articles | Metrics
    In this study, the kinetics of isopropyl palmitate synthesis including the reaction mechanism was studied based on the two-step noncatalyticmethod. The liquid-phase diffusion effect on the reaction process was eliminated by adjusting the stirring rate. The results showed that the two-step reaction followed a tetrahedral mechanism and conformed to second-order reaction kinetics. Nucleophilic attack on the carbonyl carbon afforded an intermediate, containing a tetrahedral carbon center. The intermediate ultimately decomposed by elimination of the leaving group, affording isopropyl palmitate. The experimental data were analyzed at different temperatures by the integral method. The kinetic equations of the each step were deduced, and the activation energy and frequency factor were obtained. Experiments were performed to verify the feasibility of kinetic equations, and the result showed that the kinetic equations were reliable. This study could be very significant to both industrial application and determining the continuous production of isopropyl palmitate.
    Design of a modern automatic control system for the activated sludge process in wastewater treatment
    Alexandros D. Kotzapetros, Panayotis A. Paraskevas, Athanasios S. Stasinakis
    2015, 23(8):  1340-1349.  doi:10.1016/j.cjche.2014.09.053
    Abstract ( 2298 )   PDF (1031KB) ( 178 )  
    References | Related Articles | Metrics
    The Activated Sludge Process (ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modified controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms, (reference value step increase of 50 mg·L-1) and 0.01 days for the concentration of oxygen (reference value step increase of 0.1mg·L-1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of 5×103 m3·d-1 are small. Changes in the reference values of oxygen and microorganisms (increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance (increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.
    Synthesis and optimization of utility system using parameter adaptive differential evolution algorithm
    Zeqiu Li, Wenli Du, Liang Zhao, Feng Qian
    2015, 23(8):  1350-1356.  doi:10.1016/j.cjche.2015.01.013
    Abstract ( 2006 )   PDF (2362KB) ( 62 )  
    References | Related Articles | Metrics
    Synthesis and optimization of utility system usually involve grassroots design, retrofitting and operation optimization, which should be considered in modeling process. This paper presents a general method for synthesis and optimization of a utility system. In this method, superstructure based mathematical model is established, in which different modeling methods are chosen based on the application. A binary code based parameter adaptive differential evolution algorithm is used to obtain the optimal configuration and operation conditions of the system. The evolution algorithm and models are interactively used in the calculation,which ensures the feasibility of configuration and improves computational efficiency. The capability and effectiveness of the proposed approach are demonstrated by three typical case studies.
    An aligned mixture probabilistic principal component analysis for fault detection of multimode chemical processes
    Yawei Yang, Yuxin Ma, Bing Song, Hongbo Shi
    2015, 23(8):  1357-1363.  doi:10.1016/j.cjche.2015.01.014
    Abstract ( 2005 )   PDF (793KB) ( 65 )  
    References | Related Articles | Metrics
    A novel approach named aligned mixture probabilistic principal component analysis (AMPPCA) is proposed in this study for fault detection of multimode chemical processes. In order to exploit within-mode correlations, the AMPPCA algorithm first estimates a statistical description for each operating mode by applyingmixture probabilistic principal component analysis (MPPCA). As a comparison, the combined MPPCA is employed where monitoring results are softly integrated according to posterior probabilities of the test sample in each local model. For exploiting the cross-mode correlations, which may be useful but are inadvertently neglected due to separately held monitoring approaches, a global monitoring model is constructed by aligning all local models together. In this way, bothwithin-mode and cross-mode correlations are preserved in this integrated space. Finally, the utility and feasibility of AMPPCA are demonstrated through a non-isothermal continuous stirred tank reactor and the TE benchmark process.
    Pole-placement self-tuning control of nonlinear Hammerstein system and its application to pH process control
    Zhiyun Zou, Dandan Zhao, Xinghong Liu, Yuqing Guo, Chen Guan, Wenqiang Feng, Ning Guo
    2015, 23(8):  1364-1368.  doi:10.1016/j.cjche.2015.01.009
    Abstract ( 1792 )   PDF (2720KB) ( 53 )  
    References | Related Articles | Metrics
    By taking advantage of the separation characteristics of nonlinear gain and dynamic sector inside a Hammerstein model, a novel pole placement self tuning control scheme for nonlinear Hammerstein system was put forward based on the linear system pole placement self tuning control algorithm. And the nonlinear Hammerstein system pole placement self tuning control (NL-PP-STC) algorithm was presented in detail. The identification ability of its parameter estimation algorithm of NL-PP-STC was analyzed, which was always identifiable in closed loop. Two particular problems including the selection of poles and the on-line estimation of model parameters, which may be met in applications of NL-PP-STC to real process control, were discussed. The control simulation of a strong nonlinear pH neutralization process was carried out and good control performance was achieved.
    Salting-out effect of ionic liquids on isobaric vapor-liquid equilibrium of acetonitrile-water system
    Jing Fang, Rui Zhao, HuiWang, Chunli Li, Jing Liu
    2015, 23(8):  1369-1373.  doi:10.1016/j.cjche.2015.04.011
    Abstract ( 2574 )   PDF (498KB) ( 91 )  
    References | Related Articles | Metrics
    This paper presents the vapor-liquid equilibrium (VLE) data of acetonitrile-water system containing ionic liquids (ILs) at atmospheric pressure (101.3 kPa). Since ionic liquids dissociate into anions and cations, the VLE data for the acetonitrile + water + ILs systems are correlated by salt effect models, Furter model and improved Furter model. The overall average relative deviation of Furter model and improved Furter model is 5.43% and 4.68%, respectively. Thus the salt effect models are applicable for the correlation of IL containing systems. The salting-out effect theory can be used to explain the change of relative volatility of acetonitrile-water system.
    LSER-based modeling vapor pressures of (solvent + salt) systems by application of Xiang-Tan equation
    Aynur Senol
    2015, 23(8):  1374-1383.  doi:10.1016/j.cjche.2015.04.014
    Abstract ( 2024 )   PDF (460KB) ( 127 )  
    References | Related Articles | Metrics
    The study deals with modeling the vapor pressures of (solvent+salt) systems depending on the linear solvation energy relation (LSER) principles. The LSER-based vapor pressure model clarifies the simultaneous impact of the vapor pressure of a pure solvent estimated by the Xiang-Tan equation, the solubility and solvatochromic parameters of the solvent and the physical properties of the ionic salt. It has been performed independently two structural forms of the generalized solvation model, i.e. the unified solvation model with the integrated properties (USMIP) containing nine physical descriptors and the reduced property-basis solvation model. The vapor pressure data of fourteen (solvent+salt) systems have been processed to analyze statistically the reliability of existing models in terms of a log-ratio objective function. The proposed vapor pressure approaches reproduce the observed performance relatively accurately, yielding the overall design factors of 1.0643 and 1.0702 for the integrated property-basis and reduced property-basis solvation models.
    Bienzyme system immobilized in biomimetic silica for application in antifouling coatings
    Hongwu Wang, Yanjun Jiang, Liya Zhou, Jing Gao
    2015, 23(8):  1384-1388.  doi:10.1016/j.cjche.2015.05.001
    Abstract ( 2488 )   PDF (669KB) ( 35 )  
    References | Related Articles | Metrics
    Antifouling coatings are used extensively on vessels and underwater structures. Conventional antifouling coatings contain toxic biocides and heavy metals, which may induce unwanted adverse effects such as toxicity to non-target organisms, imposex in gastropods and increased multiresistance among bacteria. Therefore, enzyme-based coatings could be a new alternative solution. A H2O2-producing bienzyme systemwas developed in this study. H2O2 can be produced from starch by the cooperation of α-amylase and glucose oxidase,which promotes the hydrolysis of polymeric chain and oxidizes the glucose to produce H2O2, respectively. The encapsulated bienzyme (A-G@BS) exhibits enhanced stabilities of thermal, pH, recycling and tolerance of xylene. The A-G@BScontaining coating releases H2O2 at rates exceeding a target of 36 nmol·cm-2·d-1 for 90 days in a laboratory assay. The results demonstrate that the method is a promising coating technology for entrapping active enzymes, presenting an interesting avenue for enzyme-based antifouling solutions.
    A new two-dimensional experimental apparatus for electrochemical remediation processes
    Yingying Gu, Rongbing Fu, Hongjiang Li, Hui An
    2015, 23(8):  1389-1397.  doi:10.1016/j.cjche.2015.05.011
    Abstract ( 2337 )   PDF (2162KB) ( 59 )  
    References | Related Articles | Metrics
    Electrochemical extraction of contaminants from soils is a promising soil decontamination technology. Various experiments have been conducted to study electrochemical reactions and geochemical processes in the electrochemical extraction using different experimental apparatuses. This paper presents the development of a new closed two-dimensional (2D) apparatus that can better simulate the field application of the technology and accurately monitor the most important electrochemical parameters to understand the process. The innovative features of the new apparatus include the outer and inner electrodes designed to apply a non-uniform electrical field across the specimen as in the field electrochemical remediation process, the probes installed to measure the 2D distribution of electrical voltage, and the gas and fluid volumemeasurement devices used to accurately monitor the gas generation and electroosmotic flowrates at both electrodes as a function of time. The components of this new apparatus and the features of each component are described. The operating procedure and some typical results from three experimentswith the apparatus are demonstrated. The results showthat the variation of the gas generation rate is in good agreement with the electric current. Their relation provides a valid evaluation for electrochemical behavior of the system and Faraday's laws of electrolysis. The 2D profiles of cadmium concentration and voltage distribution at the end of the experiment reveal the great effects of a non-uniform electrical field on the contaminant mobilization.
    Synthesis of magnetic core-shell structure Fe3O4@MCM-41 nanoparticle by vesicles in aqueous solutions
    Weiming Song, Xuesong Liu, Ying Yang, Xuejia Han, Qigang Deng
    2015, 23(8):  1398-1402.  doi:10.1016/j.cjche.2015.04.008
    Abstract ( 2778 )   PDF (2431KB) ( 40 )  
    References | Related Articles | Metrics
    In this study, magnetic core-shell structure Fe3O4@MCM-41 nanoparticles were synthesized with vesicles as soft templates. In the preparation, FeCl2 and tetraethy orthosilicate (TEOS) were selected as Fe processor and Si precursor, respectively. Stable vesicles first formed in 0.03 mol·L-1 1:2 mixture of anionic surfactant sodium dodecyl sulfate and cationic surfactant cetyltrimethyl ammonium bromide. Then, TEOS was added in the vesicle aqueous solution, leading to a highly dispersed solution. After high-temperature calcination, Fe3O4@MCM-41 nanoparticles were obtained. Their structure and morphology were characterized by Saturn Digisizer, transmission electron microscope and vibrating samplemagneto-meter. The results indicate that the vesicles are spherical and their size could be tuned between 20 and 50 nm. The average grain diameter of synthesize magnetic core-shell Fe3O4@MCM-41 particles is 100-150 nm and most of the mare in elliptical shape. The dispersion of magnetic particles is very good and magnetization values are up to 33.44 emu·g-1, which are superior to that of other Fe3O4 materials reported.
    Non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends
    Min He, Siqi Zong, Yahuan Zhou, Huaibing Guo, Qingchun Fan
    2015, 23(8):  1403-1407.  doi:10.1016/j.cjche.2015.04.012
    Abstract ( 2020 )   PDF (1976KB) ( 113 )  
    References | Related Articles | Metrics
    The non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends was investigated by differential scanning calorimetry (DSC). The Mo equation was employed to analyze the non-isothermal crystallization data. The crystallization activation energies were also evaluated by the Kissinger method. The results show that the crystallization onset temperature (Tonset) and crystallization peak temperature (Tp) decrease with the increase of the content of reactive microgel, while ΔT (Tonset-Tp), the crystallization half-time (t1/2) and the crystallization enthalpy (ΔHc) increase. The required cooling rates of blends are higher than that of neat nylon 6 in order to achieve the same relative crystallinity in a unit of time. The crystallization activation energies of the reactive microgel/nylon 6 blends are greater than those of the neat nylon 6. When the content of reactive microgel is 30%, the relative crystallinity (Xt) reaches the maximum.
    Capsella bursa-pastoris extract as an eco-friendly inhibitor on the corrosion of Q235 carbon steels in 1 mol·L-1 hydrochloric acid
    Qin Hu, Yubing Qiu, Guoan Zhang, Xingpeng Guo
    2015, 23(8):  1408-1415.  doi:10.1016/j.cjche.2015.05.002
    Abstract ( 2913 )   PDF (741KB) ( 80 )  
    References | Related Articles | Metrics
    The corrosion inhibition effect of Capsella bursa-pastoris extracts (CBE) for Q235 carbon steels in 1 mol·L-1 hydrochloric acid solutionwas studied using electrochemical methods, environmental scanning electronmicroscopy (SEM) and Ramanmicroscopy analysis. The polarization plots indicate that CBE serves as an effective,mixedtype inhibitor. Linear polarization resistance shows that increasing CBE concentration and temperature results in increased inhibition efficiency. The highest inhibition efficiency can reach 97% when adding 60 mg·L-1 CBE, which is better than some reported plant extracts under the similar environment. The adsorption of CBE molecules is found to obey the Langmuir adsorption isotherm. Some thermodynamic and kinetic parameters for the adsorption process, such as the adsorption equilibriumconstant (K), free energy of adsorption (ΔGads), activation energy of corrosion reaction (Ea) and the heat of adsorption (Qads), are calculated and discussed. SEM and Raman microscopy analysis also demonstrate the formation of a CBE inhibition film on the metal surface.
    One-pot three-component synthesis of tetrahydrobenzo[b]pyrans catalyzed by cost-effective ionic liquid in aqueous medium
    Jianguo Yang, Shuo Liu, Huanan Hu, Shibin Ren, Anguo Ying
    2015, 23(8):  1416-1420.  doi:10.1016/j.cjche.2015.04.020
    Abstract ( 2547 )   PDF (2073KB) ( 114 )  
    References | Related Articles | Metrics
    A simple and efficient method is proposed for the synthesis of tetrahydrobenzo[b]pyrans with aromatic aldehydes, active methylene compounds, and dimedone using basic ionic liquid catalyst in water. The procedure offers several advantages including short reaction time, good yield, easy procedure, and good recyclability of catalysts, which may be a practical alternative to conventional processes for preparation of 4-hpyrans.