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Table of Content
28 October 2015, Volume 23 Issue 10
    Comparison of numerical simulations and experiments in conical gas-solid spouted bed
    Shuyan Wang, Baoli Shao, Rui Liu, Jian Zhao, Yang Liu, Yikun Liu, Shuren Yang
    2015, 23(10):  1579-1586.  doi:10.1016/j.cjche.2015.07.006
    Abstract ( 2753 )   PDF (1767KB) ( 48 )  
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    Flowbehavior of gas and particles in conical spouted beds is experimentally studied and simulated using the twofluid gas-solid model with the kinetic theory of granular flow. The bed pressure drop and fountain height are measured in a conical spouted bed of 100mmI.D. at different gas velocities. The simulation results are compared with measurements of bed pressure drop and fountain height. The comparison shows that the drag coefficient model used in cylindrical beds under-predicted bed pressure drop and fountain height in conical spouted beds due to the partial weight of particles supported by the inclined side walls. It is found that the numerical results using the drag coefficient model proposed based on the conical spouted bed in this study are in good agreement with experimental data. The present study provides a useful basis for further works on the CFD simulation of conical spouted bed.
    Fluid Dynamics and Transport Phenomena
    Molecular dynamics simulation of water transport through graphene-based nanopores: Flow behavior and structure characteristics
    Xueping Yang, Xiaoning Yang, Shuyan Liu
    2015, 23(10):  1587-1592.  doi:10.1016/j.cjche.2015.05.015
    Abstract ( 2482 )   PDF (2957KB) ( 84 )  
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    The flowbehavior of pressure-drivenwater infiltration through graphene-based slit nanopores has been studied by molecular simulation. The simulated flow rate is close to the experimental values, which demonstrates the reasonability of simulation results. Water molecules can spontaneously infiltrate into the nanopores, but an external driving force is generally required to pass through the whole pores. The exit of nanopore has a large obstruction on the water effusion. The flow velocity within the graphene nanochannels does not display monotonous dependence upon the porewidth, indicating that the flowis related to the microscopic structures ofwater confined in the nanopores. Extensive structures of confined water are characterized in order to understand the flow behavior. This simulation improves the understanding of graphene-based nanofluidics, which helps in developing a new type of membrane separation technique.
    Pore-scale study based on lattice Boltzmann method of density driven natural convection during CO2 injection project
    Abdelmalek Atia, Kamal Mohammedi
    2015, 23(10):  1593-1602.  doi:10.1016/j.cjche.2015.07.010
    Abstract ( 2414 )   PDF (7302KB) ( 27 )  
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    Saline aquifers are chosen for geological storage of greenhouse gas CO2 because of their storage potential. In almost all cases of practical interest, CO2 is present on top of the liquid and CO2 dissolution leads to a small increase in the density of the aqueous phase. This situation results in the creation of negative buoyancy force for downward density-driven natural convection and consequently enhances CO2 sequestration. In order to study CO2 injection at pore-level, an isothermal Lattice Boltzmann Model (LBM)with two distribution functions is adopted to simulate density-driven natural convection in porous media with irregular geometry obtained by image treatment. The present analysis showed that after the onset of natural convection instability, the brine with a high CO2 concentration infringed into the underlying unaffected brine, in favor of the migration of CO2 into the pore structure. With low Rayleigh numbers, the instantaneous mass flux and total dissolved CO2 mass are very close to that derived from penetration theory (diffusion only), but the fluxes are significantly enhanced with high Ra number. The simulated results show that as the time increases, some chaotic and recirculation zones in the flow appear obviously, which promotes the renewal of interfacial liquid, and hence enhances dissolution of CO2 into brine. This study is focused on the scale of a few pores, but shows implications in enhanced oil/gas recovery with CO2 sequestration in aquifers.
    CFD gas-liquid simulation of oriented valve tray
    Yufeng Ma, Lijun Ji, Jiexu Zhang, Kui Chen, BinWu, YanyangWu, Jiawen Zhu
    2015, 23(10):  1603-1609.  doi:10.1016/j.cjche.2015.06.020
    Abstract ( 2061 )   PDF (3446KB) ( 59 )  
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    Computational fluid dynamics (CFD) has recentlyemerged as an effective tool for the investigation of the hydraulic parameters and efficiency of tray towers. The computation domain was established for two types of oriented valves within a tray and meshed into two parts with different grid types and sizes. The volume fraction correlation concerning inter-phase momentum transfer source was fitted based on experimental data, and built in UDF for simulation. The flow pattern of oriented valve tray under different operating conditionswas simulated under Eulerian-Eulerian framework with realizable k-ε model. The predicted liquid height from CFD simulation was in good agreement with the results of pressure drop and volume fraction correlations. Meanwhile, the velocity distribution and volume fraction of the two phases were demonstrated and analyzed, which are useful in design and analysis of the column trays.
    Biosorption of basic violet 10 onto activated Gossypium hirsutum seeds: Batch and fixed-bed column studies
    N. Sivarajasekar, R. Baskar
    2015, 23(10):  1610-1619.  doi:10.1016/j.cjche.2015.08.029
    Abstract ( 2043 )   PDF (1933KB) ( 78 )  
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    Sulphuric acid activated immature Gossypium hirsutum seed (AIGHS) was prepared to biosorbe basic violet 10 (BV10) from aqueous solutions. Methylene blue number, iodine number and Brunauer-Emmett-Teller surface analysis indicated that the AIGHS were hetero-porous. Boehm titrations and Fourier-transform infrared spectra demonstrated the chemical heterogeneity of the AIGHS surface. Batch biosorption studies were used to examine the effects of process parameters in the following range: pH 2-12, temperature 293-313 K, contact time 1-5 h and initial concentration 200-600 mg·L-1. The matching of equilibrium data with the Langmuir-Freundlich formof isotherms indicated that the BV10 was adsorbed via chemisorption and pore diffusion. Kinetic investigation indicated multiple order chemisorption through an Avrami kinetic model. Film diffusion controlled the rate of BV10 biosorption onto AIGHS. The spontaneous and endothermic nature of sorptionwas corroborated by thermodynamic study. Continuous biosorption experimentswere performed using a fixed-bed column and the influence of operating parameters was explored for different ranges of initial concentration 100-300 mg·L-1, bed height 5-10 cm, and flow rate 2.5-4.5 ml·min-1. A dose response model accurately described the fixed-bed biosorption data. An external mass transfer correlation was formulated explaining BV10-AIGHS sorption.
    Removal of strontium ions from aqueous solution using hybrid membranes: Kinetics and thermodynamics
    Zhicheng Chu, Junsheng Liu, Chengliang Han
    2015, 23(10):  1620-1626.  doi:10.1016/j.cjche.2015.08.011
    Abstract ( 2280 )   PDF (4908KB) ( 43 )  
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    The removal of radionuclide from radioactive wastewater has captured much attention. Strontium-90 is one of the major radionuclides. To develop a new type of adsorbents to remove strontium ions from the radioactive wastewater, in this study, novel hybrid membranes were prepared and characterized. The adsorption kinetics, thermodynamic parameters of ΔG, ΔH and ΔS, as well as surface SEM and EDS images were used to investigate the removal of strontium ions from stimulated radioactive wastewater using the previously prepared hybrid membranes as efficient adsorbents. The study of kinetic model confirmed that the adsorption of strontium ions on these hybrid membranes followed the Lagergren pseudo-second order model. Moreover, it was proved that the adsorption of strontium ions on these samples was solely controlled by intraparticle diffusion. The negative values of ΔG and the positive values of ΔH indicated that the adsorption of strontium ions on samples A-D is a spontaneous and endothermic process in nature. Furthermore, surface SEM and DES images give significant evidence to confirm the existence of strontiumions on the surface of the adsorbed samples. These findings demonstrate that these hybrid membranes are promising adsorbents for the removal of strontium ions from aqueous solution and can be potentially applied in the adsorptive separation of radionuclides from the radioactive wastewater.
    Numerical simulation of fixed bed reactor for oxidative coupling of methane over monolithic catalyst
    Zhao Zhang, Ziqi Guo, Shengfu Ji
    2015, 23(10):  1627-1633.  doi:10.1016/j.cjche.2015.07.025
    Abstract ( 2151 )   PDF (4105KB) ( 77 )  
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    A three-dimensional geometric modelwas set up for the oxidative coupling of methane (OCM) fixed bed reactor loaded with Na3PO4-Mn/SiO2/cordierite monolithic catalyst, and an improved Stansch kinetic model was established to calculate the OCMreactions using the computational fluid dynamicsmethod and Fluent software. The simulation conditions were completely the same with the experimental conditions that the volume velocity of the reactant is 80 ml·min-1 under standard state, the CH4/O2 ratio is 3 and the temperature and pressure is 800 ℃ and 1 atm, respectively. The contour of the characteristic parameters in the catalyst bed was analyzed, such as the species mass fractions, temperature, the heat flux on side wall surface, pressure, fluid density and velocity. The results showed that the calculated valuesmatchedwell with the experimental values on the conversion of CH4 and the selectivity of products (C2H6, C2H4, CO,CO2 and H2) in the reactor outlet with an error range of ±4%. The mass fractions of CH4 and O2 decreased from 0.600 and 0.400 at the catalyst bed inlet to 0.445 and 0.120 at the outlet, where the mass fractions of C2H6, C2H4, CO and CO2 were 0.0245, 0.0460, 0.0537 and 0.116, respectively. Due to the existence of laminar boundary layer, the mass fraction contours of each species bent upwards in the vicinity of the boundary layer. The volume of OCM reaction was changing with the proceeding of reaction, and the total moles of products were greater than reactants. The flow field in the catalyst bed maintained constant temperature and pressure. The fluid density decreased gradually from 2.28 kg·m-3 at the inlet of the catalyst bed to 2.18 kg·m-3 at the outlet of the catalyst bed, while the average velocity magnitude increased from 0.108 m·s-1 to 0.120 m·s-1.
    Non-isothermal decomposition kinetics of hydrogarnet in sodium carbonate solution
    Xiaofeng Zhu, Ting an Zhang, YanxiuWang, Guozhi Lu, Weiguang Zhang, CongWang, Aichun Zhao
    2015, 23(10):  1634-1639.  doi:10.1016/j.cjche.2015.07.029
    Abstract ( 2360 )   PDF (796KB) ( 82 )  
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    Carbonation decomposition of hydrogarnet is a significant reaction of the calcification-carbonation new method for alumina production by using low-grade bauxite. In this work, non-isothermal decomposition kinetics of hydrogarnet in sodium carbonate solution was studied by high-pressure differential scanning calorimetry (HPDSC) at different heating rates of 2, 5, 8, 10, 15 and 20 K·min-1, respectively. The activation energy (Ea) was calculated with the help of isoconversional method (model-free), and the reaction mechanism was determined by the differential equation method. The calculated activation energy of this reaction was 115.66 kJ·mol-1. Furthermore, the mechanism for decomposition reaction is Avrami-Erofeev (n = 1.5), and the decomposition process is diffusion-controlled.
    Photorheology and rheokinetics of CTAB/chlorocinnamic acid micelles
    Bo Fang, Tingyang Lu, Jinshuang Wang, Lianghao He, Haiwei Lu, Lichen Yu, Jie Chen
    2015, 23(10):  1640-1646.  doi:10.1016/j.cjche.2015.08.002
    Abstract ( 2294 )   PDF (851KB) ( 35 )  
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    The photosensitive micellar systemwith prospect in drag reduction and heat transfer enhancement has been the research focus of science and industry. In this paper, a newtype of photosensitive micellar systemformed by cetyl trimethylammonium bromide (CTAB) and trans-chlorocinnamic acid (trans-ClCA) was investigated. The effects of counter-ion concentration, surfactant concentration, UV irradiation time, and the position of substituent groups of counter-ion on photorheological properties were discussed. The results indicate that after UV irradiation the relative viscosity and thixotropy of micellar systems reduce obviously. At the same time, the relative viscosity of micelle systems and concentration of trans-ClCA decline during UV irradiation time. The flow curves of micellar solutions before and after UV irradiation could be described by non-linear co-rotational Jeffreys model correctly. The rheokinetic equation was firstly established to describe the relationship between relative viscosity of micelle systems and conversion of trans-ClCA.
    Study of M-ZSM-5 nanocatalysts (M: Cu, Mn, Fe, Co …) for selective catalytic reduction of NO with NH3: Process optimization by Taguchi method
    Parvaneh Nakhostin Panahi, Darush Salari, Aligholi Niaei, Seyed Mahdi Mousavi
    2015, 23(10):  1647-1654.  doi:10.1016/j.cjche.2015.08.003
    Abstract ( 2529 )   PDF (2958KB) ( 78 )  
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    A series of different transition metals (V, Co, Cr, Mn, Fe, Ni, Cu and Zn) promoted H-ZSM-5 catalysts were prepared by impregnation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic activity of these catalysts was evaluated for the selective catalytic reduction (SCR) of NO with NH3 as reductant in the presence of oxygen. The results revealed that the catalytic activity of Cu-ZSM-5 nanocatalyst for NO conversion to N2 was 80% at 300 ℃, which was the best among various promoted metals. Design of experiments (DOEs) with Taguchi method was employed to optimize NH3-SCR process parameters such as NH3/NO ratio, O2 concentration, and gas hourly space velocity (GHSV) over Cu-ZSM-5 nanocatalyst at 250 and 300 ℃. Results showed that the most important parameter in NH3-SCR of NO is O2 concentration; followed by NH3/NO ratio and GHSV has little importance. The NO conversion to N2 of 63.1% and 94.86%was observed at 250 ℃ and 300 ℃, respectively under the obtained optimum conditions.
    Exploring suitable ZSM-5/MCM-41 zeolites for catalytic cracking of n-dodecane: Effect of initial particle size and Si/Al ratio
    Guozhu Li, Zhenheng Diao, Jindan Na, Li Wang
    2015, 23(10):  1655-1661.  doi:10.1016/j.cjche.2015.08.010
    Abstract ( 2235 )   PDF (2305KB) ( 60 )  
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    In this study, various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkalidesilication and surfactant-directed recrystallization of ZSM-5. The effects of particle size and Si/Al ratio of initial ZSM-5 zeolites on the structure and catalytic performance of ZSM-5/MCM-41 composites are studied. The results of XRD, TEM N2-adsorption-desorption, NH3-TPD and in situ FT-IR revealed that ordered hexagonal MCM-41 mesopores with 3-4 nm pore size were formed around ZSM-5 crystals, and the specific surface area and mesopore volume of composites increased with increasing the Si/Al ratio of initial ZSM-5. Catalytic cracking of n-dodecane (550 ℃, 4 MPa) showed that the ZSM-5/MCM-41 composites obtained from the high Si/Al ratio and nano-sized initial ZSM-5 zeolites exhibited superior catalytic performance, with the improvement higher than 87% in the catalytic activities and 21% in the deactivation rate compared with untreated zeolites. This could be ascribed to their suitable pore structure, which enhanced the diffusion of reactant molecules in pores of catalysts.
    Multi-objective nonlinear model predictive control through switching cost functions and its applications to chemical processes
    Defeng He, Shiming Yu, Li Yu
    2015, 23(10):  1662-1669.  doi:10.1016/j.cjche.2015.07.005
    Abstract ( 1994 )   PDF (895KB) ( 90 )  
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    This paper proposes a switching multi-objective model predictive control (MOMPC) algorithm for constrained nonlinear continuous-time process systems. Different cost functions to be minimized inMPC are switched to satisfy different performance criteria imposed at different sampling times. In order to ensure recursive feasibility of the switching MOMPC and stability of the resulted closed-loop system, the dual-mode control method is used to design the switching MOMPC controller. In this method, a local control law with some free-parameters is constructed using the control Lyapunov function technique to enlarge the terminal state set of MOMPC. The correction termis computed if the states are out of the terminal set and the free-parameters of the local control laware computed if the states are in the terminal set. The recursive feasibility of the MOMPC and stability of the resulted closed-loop system are established in the presence of constraints and arbitrary switches between cost functions. Finally, implementation of the switching MOMPC controller is demonstrated with a chemical process example for the continuous stirred tank reactor.
    An efficient latent variable optimization approach with stochastic constraints for complex industrial process
    Zhengshun Fei, Kangling Liu, Bin Hu, Jun Liang
    2015, 23(10):  1670-1678.  doi:10.1016/j.cjche.2015.05.009
    Abstract ( 1956 )   PDF (1594KB) ( 45 )  
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    For complex chemical processes, process optimization is usually performed on causalmodels fromfirst principle models. When the mechanism models cannot be obtained easily, restricted model built by process data is used for dynamic process optimization. A new strategy is proposed for complex process optimization, in which latent variables are used as decision variables and statistics is used to describe constraints. As the constraint condition will be more complex by projecting the original variable to latent space, Hotelling T2 statistics is introduced for constraint formulation in latent space. In this way, the constraint is simplified when the optimization is solved in low-dimensional space of latent variable. The validity of the methodology is illustrated in pH-level optimal control process and practical polypropylene grade transition process.
    Intradiffusion, density and viscosity studies in binary liquid systems of acetylacetone + DMF/DMSO/benzene at 303.15 K and 333.15 K
    Xiaojuan Chen, Zhaoxun Lian, Haimin Zhong, Liuping Chen
    2015, 23(10):  1679-1684.  doi:10.1016/j.cjche.2015.07.027
    Abstract ( 2560 )   PDF (491KB) ( 80 )  
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    Intradiffusion coefficients of acetylacetone (AcAc) and DMF/DMSO/benzene in binary systems over the entire concentration range at 303.15 K were determined by 1H diffusion-order spectroscopy (DOSY) nuclear magnetic resonance (NMR)method based pulse field gradient (PFG). The densities and viscosities of the above three binary systemsat 303.15 Kwere also studied andemployed to calculate the excessmolar volumes (VE) and deviations in viscosity (Δη). Besides, experiments were carried out at 333.15 K for the systemof AcAc+DMF. The solvent and temperature effect upon the difference in D between enol and keto tautomers, the tautomeric equilibrium and excess properties (VE and Δη) were discussed as well. Isotherms of VE as a function of mole fraction of AcAc (x1) show positive deviations in benzene but negative deviations in DMF and DMSO, whereas isotherms of Δη as a function of x1 record positive deviations in DMF but negative in benzene and DMSO. VE values show more negative and Δη values are less positive in the system of AcAc + DMF at 333.15 K compared to 303.15 K. The VE and Δη were fitted to a Redlich-Kister type equation and the measured results were interpreted concerning molecular interactions in the solutions.
    Experimental investigation of methyl tert-butyl ether dissolution in saturated porous media
    Hong Li, Lei Zhao, Xin Gao, Xingang Li
    2015, 23(10):  1685-1690.  doi:10.1016/j.cjche.2015.08.022
    Abstract ( 1925 )   PDF (571KB) ( 38 )  
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    This study aims to investigate methyl tert-butyl ether (MTBE) dissolution in saturated porous media. A series of 1D columnexperimentswere conducted in laboratory to obtain MTBE dissolution datawith different groundwater velocity, initial MTBE saturation and grain size of porous medium, and in the presence of other nonaqueous liquids. Results indicate that higher groundwater velocity increases MTBE dissolution rate and higher initial MTBE saturation reduces effective permeability to slow MTBE dissolution rate. Smaller grain size medium gives higher MTBE dissolution rate because of higher permeability. The addition of trichloroethylene enhances MTBE dissolution, with an optimal mass ratio of 10:2, while the presence of p-xylene prolongs complete dissolution of MTBE. Mass transfer correlations are developed for MTBE dissolution rate based on the degree of MTBE saturation Sn. Mass transfer rate is characterized by Re' with a high exponent for 0.3000 b Sn b 0.5482, while it is related to medium grain size and Sn for Sn ≤ 0.3000.
    TG-FTIR analysis of pyrolusite reduction bymajor biomass components
    Yunfei Long, Le Ruan, Xiaoyan Lü, Yiju Lü, Jing Su, YanxuanWen
    2015, 23(10):  1691-1697.  doi:10.1016/j.cjche.2015.08.028
    Abstract ( 2443 )   PDF (1741KB) ( 87 )  
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    Pyrolusite reduction processes by three major biomass components cellulose, hemicelluloses and lignin, represented by CP, HP and LP, respectively, were investigated by thermogravimetric analyzer coupled with Fourier transforminfrared spectrometry (TG-FTIR). The Šesták-Berggren (SB) equationwas used to evaluate the kinetics of reduction processes. TG analysis reveals that the main reduction processes occur at 250-410 ℃, 220-390 ℃, and 190-410 ℃ for CP, HP, and LP, respectively. FT-IR and XRD results indicate that various reducing volatiles (e.g. aldehydes, furans, ketones and alcohols) are produced from the pyrolysiswith the three major components, which directly reduce MnO2 in ore to MnO. The processes are described by the SB equationwith three parameters (m, n, p). Their non-zero values suggest that pyrolusite reduction is controlled by the diffusion of reducing gaseous products through an ash/inert layer associated with minerals. The apparent activation energies for pyrolusite reduction by CP, HP and LP are 40.48, 25.70 and 40.10 kJ·mol-1, respectively.
    Energy, Resources and Environmental Technology
    Adsorption and degradation of norfloxacin by a novel molecular imprinting magnetic Fenton-like catalyst
    Mingjie Huang, Tao Zhou, XiaohuiWu, Juan Mao
    2015, 23(10):  1698-1704.  doi:10.1016/j.cjche.2015.08.030
    Abstract ( 2353 )   PDF (2313KB) ( 78 )  
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    In this study, a novel magnetically separable adsorbent, molecular imprinting magnetic γ-Fe2O3/crosslinked chitosan composites (MIPs), were prepared by a microemulsion process. Adsorption and Fenton-like oxidative degradation of a model pharmaceutical pollutant norfloxacin (NOR) by using MIPs were investigated. Various characterization methodswere used to study the properties ofMIPs, and it is suggested that the hydroxyl groups are the main adsorption sites for NOR. MIPs present better selective adsorption for NOR than its reference antibiotic sulfadiazine. The NOR adsorption data can be well fitted by Langmuir isotherm model and pseudosecond- order kinetic model. The optimum pH range for NOR adsorption is 7-10. In addition, the MIP-catalyzed Fenton-like system (MIPs/H2O2) exhibits remarkably faster removal rate for NOR than the case of γ-Fe2O3/ H2O2. The result indicates that MIPs will be a good functional material in decontamination of pharmaceutical wastewaters since MIPs can be magnetically recycled after the treatment.
    Adsorption of cadmium ions from aqueous solutions by activated carbon with oxygen-containing functional groups
    Yu Bian, Zhaoyong Bian, Junxiao Zhang, Aizhong Ding, Shaolei Liu, Lei Zheng, Hui Wang
    2015, 23(10):  1705-1711.  doi:10.1016/j.cjche.2015.08.031
    Abstract ( 2320 )   PDF (3526KB) ( 75 )  
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    The adsorption of aqueous cadmium ions (Cd(II)) have been investigated for modified activated carbon (AC-T) with oxygen-containing functional groups. The oxygen-containing groups of AC-T play an important role in Cd(II) ion adsorption onto AC-T. The modified activated carbon is characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results of batch experiments indicate that the maximal adsorption could be achieved over the broad pH range of 4.5 to 6.5. Adsorption isotherms and kinetic study suggest that the sorption of Cd(II) onto AC-T produces monolayer coverage and that adsorption is controlled by chemical adsorption. And the adsorbent has a good reusability. According to the FT-IR and XPS analyses, electrostatic attraction and cation exchange between Cd(II) and oxygen-containing functional groups on AC-T are dominant mechanisms for Cd(II) adsorption.
    Biological treatment of high NH4+-N wastewater using an ammonia-tolerant photosynthetic bacteria strain (ISASWR2014)
    Qin Zhou, Guangming Zhang, Xiang Zheng, Guohua Liu
    2015, 23(10):  1712-1715.  doi:10.1016/j.cjche.2015.08.018
    Abstract ( 1949 )   PDF (539KB) ( 77 )  
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    Wastewaterwith high NH4+-N is difficult to treat by traditional methods. So in this paper, a wild strain of photosynthetic bacteria was used for high NH4+-N wastewater treatment together with biomass recovery. Isolation, identification, and characterization of the microorganism were carried out. The strain was inoculated to the biological wastewater treatment unit. The impacts of important factorswere examined, including temperature, dissolved oxygen, and light intensity. Results showed that photosynthetic bacteria could effectively treat high NH4+- Nwastewater. Forwastewaterwith NH4+-N of 2300 mg · L-1, COD/N=1.0, 98.3% of COD was removed, and cell concentration increased by 43 times. The optimal conditions for the strain's cell growth and wastewater treatment were 30 ℃, dissolved oxygen of 0.5-1.5 mg · L-1 and a light intensity of 4000 lx. Photosynthetic bacteria could bear a lower C/N ratio than bacteria in a traditionalwastewater treatment process, but the NH4+-N removal was only 20%-40% because small molecule carbon source was used prior to NH4+-N. Also, the use of photosynthetic bacteria in chickenmanurewastewater containingNH4+-Nabout 7000mg· L-1 proved that photosynthetic bacteria could remove NH4+-N in a real case, finally, 83.2% of NH4+-N was removed and 66.3% of COD was removed.
    Effect of PSA tin plating process on trace lead in tin coating
    Binghu Li, Kuaikuai Guo, Changsheng Liu
    2015, 23(10):  1716-1720.  doi:10.1016/j.cjche.2015.08.001
    Abstract ( 2303 )   PDF (4056KB) ( 80 )  
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    In this paper, effects of conditions in phenol sulfonic acid (PSA) plating for tin coating of MR low carbon aluminum killed steel on trace Pb were examined. Trace Pb was measured by atomic absorption spectrometry (AAS) and glow discharge spectrometry, and coating morphology was observed by scanning electronic microscopy (SEM). Corrosion resistance of the tin coating was analyzed by electrochemical methods. The results indicated that Pb content in the tin coating reduced as bath temperature increased. When the temperature exceeded 40 ℃, the grains in the coating were coarse and loose, reducing the corrosion resistance. As current density increased, Pb content increased rapidly,while lowcurrent density plating could lead to drain regions. The plating speed had no obvious effect on trace Pb in tin coating. In the tin plating layer, Pb was enriched at the surface and gradually reduced to zero along the depth. At bath temperature of 40 ℃ and current density of 20 A·dm-2, the amount of Pb could be less than 100 mg·kg-1 with excellent corrosion resistance.
    Materials and Product Engineering
    Preparation and characterization of monodisperse zirconia spherical nanometer powder via lamellar liquid crystal template method
    Weiyan He, Jinrong Liu, Zhenzhu Cao, Caihong Li, Yanfang Gao
    2015, 23(10):  1721-1727.  doi:10.1016/j.cjche.2015.08.032
    Abstract ( 2110 )   PDF (4039KB) ( 93 )  
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    Cubic phase spherical zirconia nano-powderwas prepared by a direct template route in the lamellar liquid crystal formed by polyoxyethylene tert-octylphenyl ether (Triton X-100)/sodium dodecyl sulfate (SDS)/H2O. The precursor powder and zirconia powder were characterized by XRD, FT-IR, TG/DSC, TEM, and SEM methods. Results show that the stability of the lamellar liquid crystal is controlled by NH3 · H2O concentration. The size of nanoparticles is greatly affected by NH3·H2Oand ZrOCl2 · 8H2O concentrations. The zirconia nanoparticles shownarrow particle size distribution of 10-30 nm.
    Synthesis and characterization of switchable ionic compound based on DBU, CH3OH, and CO2
    Yuan Xie, Richard Parnas, Bin Liang, Yingying Liu, Chuandong Tao, Houfang Lu
    2015, 23(10):  1728-1732.  doi:10.1016/j.cjche.2015.08.005
    Abstract ( 2234 )   PDF (813KB) ( 56 )  
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    Switchable ionic compounds have wide applications in chemical processes. A switchable ionic compound based on 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU), CH3OH and CO2 was synthesized and characterized. DBU/ CH3OH/CO2 ionic compound was prepared in the presence of excess methanol, and then the excess methanol was removed by reduced pressure distillation in CO2 atmosphere. The product yield (100%) reached the theoretical maximumfor the first time. Its structurewas identified by NMR, FT-IR, and XRD. The crystal product shows 8 strong peaks in XRD at 2θ values of 16.0547°, 16.4308°, 16.7651°, 18.8714°, 19.2140°, 21.9471°, 22.0780°, and 25.5661°. Its decomposition onset temperature (53 ℃) was affirmed by TGA, which is lower than its melting point. And its ionic switch point was measured by conductivity.
    Research Note
    Preparation and simulation of a taro flavor
    Guangyong Zhu, Zuobing Xiao, Rujun Zhou, Donghua Lei
    2015, 23(10):  1733-1735.  doi:10.1016/j.cjche.2015.07.026
    Abstract ( 1781 )   PDF (227KB) ( 175 )  
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    Flavors represent a small but significant segment of food industry. Taro gives a pleasant nut-like odor when cooked. Taro flavor can be used in many products, so developing a taro flavor is of interests. This paper concentrates on preparation and simulation of taro flavor according to the notes of taro, which are distinct flavors or odor characteristics. The results show that the notes of taro flavor can be classified as caramellic note, roast note, milky note, beany note, green note, aldehydic note, sweet note, nutty note, vegetative note, and fruity note. According to the notes of cooked taro odor and the raw materials selected, a typical taro flavor formula is given. The taro flavor blended is pleasant, harmonious, and has characteristics of the odor of cooked natural taro.