Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization

Chongqing, China

Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization

Chongqing, China

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Liu Z.,Chongqing University | Liu Z.,Tsinghua University | He H.,Chongqing University | He H.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 7 more authors.
Asia-Pacific Journal of Chemical Engineering | Year: 2015

During fluid mixing in stirred reactor, energy, which spreads among the fluid with the impeller, is used for fluid rotation and internal transfer. Meanwhile, a part of the energy is consumed by fluid mixing noise. The premises of effective mixing are to improve utilization rate of energy. The energy-saving and noise reduction behavior of rigid-flexible combination impeller in fluid mixing were studied by adopting the combination of numerical simulation and experimental analysis. Comparative experiments were carried out to study the noise variation between rigid-flexible combination impeller and rigid impeller at 210 rpm. The results showed that the energy was mainly concentrated at the tip of rigid impeller (the maximum speed of fluid was 2.85 m/s, while turbulent kinetic energy was 0.32 m2/s2). Meanwhile, the energy at the tip of rigid-flexible combination impeller was thoroughly dissipated (the maximum speed of fluid was 2.31 m/s, while turbulent kinetic energy was 0.26 m2/s2), which evenly distributed the energy at the flow field, thereby contributing to good mixing performance. The sound pressure level of the rigid-flexible combination impeller was 7% lower than that of rigid impeller at the same location, whereas the measured value at the surface and the simulated values were identical. Copyright © 2015 Curtin University of Technology and John Wiley & Sons, Ltd. Copyright © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.


Liu Z.,Chongqing University | Liu Z.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Zheng X.,Chongqing University | Zheng X.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 6 more authors.
Chemical Engineering and Processing: Process Intensification | Year: 2014

Mixing is crucial in the dispersion of two immiscible fluids. The rational design of an impeller is necessary to form suitable flow conditions and improve fluid mixing efficiency. A double rigid-flexible combination impeller was designed by connecting the upper and lower rigid impeller blades with flexible pieces. Experimental measurements were performed in a laboratory-scale mixer-settler under different impeller types. The largest Lyapunov exponent (LLE) and multi-scale entropy (MSE) were investigated using Matlab. Results showed that the double rigid-flexible combination impeller enhanced liquid-liquid mixing in the mixer-settler through the multiple-body motion behavior triggered by the swings of flexible pieces. At the optimum mixing point of each impeller, the LLEs of the double impeller, double rigid combination impeller, and double rigid-flexible combination impeller were 0.018, 0.055, and 0.057, respectively. At 75. rpm, the MSE of the combination impellers was obviously greater than that of the double impeller, and the rigid-flexible combination impeller had larger MSE than the double rigid combination impeller. The mixing efficiency of the rigid-flexible combination impeller increased with increasing width and quantity of the flexible piece. The quantity of rigid blade slice also influenced the enhancement of mixing ability. The double rigid-flexible combination impeller intensified the chaotic mixing of the two-phase fluid by changing the flow field structure and energy dissipation mode, ultimately achieving an efficient-mixing operation. © 2014 Elsevier B.V.


Jiang C.,Chongqing University | Jiang C.,Key Laboratory of Low Grade Energy Utilization Technologies & Systems of the Ministry of Education | Jiang C.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Zhang M.,Key Laboratory of Low Grade Energy Utilization Technologies & Systems of the Ministry of Education | And 4 more authors.
Huagong Xuebao/CIESC Journal | Year: 2014

The solubility of Na2CrO4, NaAlO2 and Na2SiO3 in the multicomponent systems related to the manufacture of chromium compounds by liquid-phase oxidation of chromite was measured by using the equilibrium analysis method at the atmospheric pressure and temperature ranging from 353.15 K to 403.15 K, which include ternary systems NaOH-H2O-Na2CrO4, NaOH-H2O-NaAlO2 and NaOH-Na2SiO3-H2O, quaternary systems NaOH-H2O- Na2CrO4-Na2SiO3, NaOH-H2O-Na2CrO4-NaAlO2 and NaOH-NaAlO2-Na2SiO3-H2O, and quinary systems NaOH-H2O-Na2CrO4-Na2SiO3-NaAlO2. Except the Na2CrO4 solubility in ternary system NaOH-H2O-Na2CrO4, in which NaOH concentration varied from 100 g·L-1 to 800 g·L-1, the NaOH concentration was constant at 500 g·L-1. The experimental data were correlated by the Antonie equation, λ-h equation, and Apelblat equation, demonstrating that the Apelblat equation can well predict the solubility of the systems. The results show that the presence of NaAlO2 and Na2SiO3 decreases Na2CrO4 solubility, while the coexistence of NaAlO2 and Na2SiO3 has less effect than the presence of single NaAlO2 and Na2SiO3. ©All Rights Reserved


Cheng J.,Chongqing University | Cheng J.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Wang N.,University of Kansas | Zhao D.,Chongqing University | And 11 more authors.
Bioresource Technology | Year: 2016

Three kinds of sulfonated cross-linked chitosan (SCCR) immobilized with metal ions of Cu2+, Fe3+ and Zn2+ individually were synthesized and firstly used as solid acid catalysts in the hydrolysis of bamboo biomass. FTIR spectra showed that metal ions had been introduced into SCCR and the N-metal ions coordinate bound was formed. The particle sizes of these catalysts were about 500–1000 μm with a pore size of 50–160 μm. All of the three kinds of catalysts performed well for bamboo hydrolysis with 1-butyl-3-methyl-imidazolium chloride used as solvent. The most effective one was sulfonated cross-linked chitosan immobilized with Fe3+ (Fe3+-SCCR). TRS yields were up to 73.42% for hydrolysis of bamboo powder in [C4mim]Cl with Fe3+-SCCR at 120 °C and 20 RPM after 24 h. These novel chitosan-based metal ions immobilized solid acid catalysts with ionic liquids as the solvent might be promising to facilitate cost-efficient conversion of biomass into biofuels and bioproducts. © 2016 Elsevier Ltd


Zhang X.-R.,Chongqing University | Zhang X.-R.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Liu Z.-H.,Chongqing University | Liu Z.-H.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 6 more authors.
International Journal of Minerals, Metallurgy and Materials | Year: 2015

In the present study, a response surface methodology was used to optimize the electroleaching of Mn from low-grade pyrolusite. Ferrous sulfate heptahydrate was used in this reaction as a reducing agent in sulfuric acid solutions. The effect of six process variables, including the mass ratio of ferrous sulfate heptahydrate to pyrolusite, mass ratio of sulfuric acid to pyrolusite, liquid-to-solid ratio, current density, leaching temperature, and leaching time, as well as their binary interactions, were modeled. The results revealed that the order of these factors with respect to their effects on the leaching efficiency were mass ratio of ferrous sulfate heptahydrate to pyrolusite > leaching time > mass ratio of sulfuric acid to pyrolusite > liquid-to-solid ratio > leaching temperature > current density. The optimum conditions were as follows: 1.10:1 mass ratio of ferrous sulfate heptahydrate to pyrolusite, 0.9:1 mass ratio of sulfuric acid to pyrolusite, liquid-to-solid ratio of 0.7:1, current density of 947 A/m2, leaching time of 180 min, and leaching temperature of 73°C. Under these conditions, the predicted leaching efficiency for Mn was 94.1%; the obtained experimental result was 95.7%, which confirmed the validity of the model. © 2015, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.


Hu X.,Chongqing University | Hu X.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Chen N.,Chongqing University | Li W.,Chongqing University
Journal of Molecular Modeling | Year: 2016

Safety prediction is crucial to the molecular design or the material design of explosives, and the predictions based on any single factor alone will cause much inaccuracy, leading to a desire for a method on multi-bases. The presented proposes an improved method for fast screening explosive safety by combining a crystal packing factor and a molecular one, that is, steric hindrance against shear slide in crystal and molecular stability, denoted by intermolecular friction symbol (IFS) and bond dissociation energy (BDE) of trigger linkage respectively. Employing this BDE-IFS combined method, we understand the impact sensitivities of 24 existing explosives, and predict those of two energetic-energetic cocrystals of the observed CL-20/BTF and the supposed HMX/TATB. As a result, a better understanding is implemented by the combined method relative to molecular stability alone, verifying its improvement of more accurate predictions and the feasibility of IFS to graphically reflect molecular stacking in crystals. Also, this work verifies that the explosive safety is strongly related with its crystal stacking, which determines steric hindrance and influences shear slide. © 2016, Springer-Verlag Berlin Heidelberg.


Shu J.,Chongqing University | Shu J.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Liu R.,Chongqing University | Liu R.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 6 more authors.
Environmental Science and Pollution Research | Year: 2015

Electrolytic manganese residue (EMR) is a solid waste found in filters after sulphuric acid leaching of manganese carbonate ore, which mainly contains manganese and ammonia nitrogen and seriously damages the ecological environment. This work demonstrated the use of electrokinetic (EK) remediation to remove ammonia nitrogen and manganese from EMR. The transport behavior of manganese and ammonia nitrogen from EMR during electrokinetics, Mn fractionation before and after EK treatment, the relationship between Mn fractionation and transport behavior, as well as the effects of electrolyte and pretreatment solutions on removal efficiency and energy consumption were investigated. The results indicated that the use of H2SO4 and Na2SO4 as electrolytes and pretreatment of EMR with citric acid and KCl can reduce energy consumption, and the removal efficiencies of manganese and ammonia nitrogen were 27.5 and 94.1 %, respectively. In these systems, electromigration and electroosmosis were the main mechanisms of manganese and ammonia nitrogen transport. Moreover, ammonia nitrogen in EMR reached the regulated level, and the concentration of manganese in EMR could be reduced from 455 to 37 mg/L. In general, the electrokinetic remediation of EMR is a promising technology in the future. © 2015 Springer-Verlag Berlin Heidelberg


Shu J.,Chongqing University | Shu J.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Liu R.,Chongqing University | Liu R.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 6 more authors.
Journal of Cleaner Production | Year: 2016

Ammonia and manganese were simultaneously removed from electrolytic metal manganese residue leachate using phosphate salt. The influence of different N:P ratios and pH were investigated. Phase transition and decomposing behavior of precipitates and the characterization of the precipitates pyrolysis were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential thermal analysis, and scanning electron microscope. In the laboratory experiment, under the condition of 1:1.15 N:P ratio and 9.5 pH value, removal efficiencies of ammonia and manganese from the residue leachate were achieved 95.0% and 99.9%, respectively, and remaining concentration of orthophosphate was as low as 12 mg L−1. In the process, manganese was first removed as Mn3(PO4)2·7H2O, and then ammonia was removed as NH4MgPO4·6H2O. In addition, MgNaPO4, MgHPO4, Mg2P2O7, Na3PO4 and MnO2 were generated during precipitate pyrolysis process, and the ammonia removal efficiency decreased from 84.0% in the first cycle to 66.0% in the fifth, and manganese removal efficiency was approximately 99.0%. Economic evaluation shows that recycling the precipitates for three times could save 68.4% cost on average, compared to the use of pure chemicals. © 2016 Elsevier Ltd


Shu J.,Chongqing University | Shu J.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Liu R.,Chongqing University | Liu R.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 6 more authors.
Journal of Electroanalytical Chemistry | Year: 2016

High-valent manganese was hard to be extracted from electrolytic manganese residues. To strengthen the extraction of Mn, electrochemical extraction method was investigated in this work. The mechanisms of the electrochemical extraction were examined along with the electrochemical performance of the reaction system via X-ray diffraction, scanning electron microscopy, X-ray Fluorescence, and BET. Results show that high-valent manganese can be reduced effectively under an electric field. The extraction efficiencyof manganese reached 96.2% under the optimum conditions of current density 25 mA/cm2, 9.2 wt% H2SO4, solid-to-liquid ratio of 1:5, room temperature, 1:1.0 M ratio of Mn to Fe2 + and 60 min extraction. The extraction efficiency of manganese is 51.8% higher than that attained under the same conditions without an electric field and Fe2 +. Meanwhile, the manganese content in residue decreased from 2.34% to 0.09%. © 2016 Elsevier B.V.


Ma X.,Chongqing University | Ma X.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Tang J.,Chongqing University | Tang J.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 6 more authors.
RSC Advances | Year: 2016

Ammonia in electrolytic manganese residue (EMR) constitutes potentially severe environmental risks. As an efficient, environment-friendly technology, electro-oxidation of ammonia in EMR was investigated in the present work. The influence of different metal ions coexisting with ammonia in EMR on the electro-oxidation of ammonia was evaluated and the relevant mechanism was deduced by phase transformation analysis through X-ray diffraction, X-ray fluorescence, scanning electron microscopy, flame atomic absorption spectrometry, and spectrophotometry. Results showed that (1) Mn2+, Ca2+, Mg2+, Na+, and K+ coexist with ammonia in the water-leach liquor of EMR, (2) Mn2+ inhibits the reaction whereas Ca2+ and Mg2+ demonstrate no distinct influence on the electro-oxidation of ammonia, and (3) Mn2+ and Cl- react emulously on the anode. MnO2 hinders the generation of free chlorine; thus, the presence of Mn2+ exerts a crucial impact on ammonia removal. So, it can be considered that further utilization of EMR can be realized by recycling Mn2+ first and then removing effectively ammonia through electro-oxidation method. © 2016 The Royal Society of Chemistry.

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