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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Gu D.,Chongqing University | Gu D.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Liu Z.,Chongqing University | Liu Z.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 6 more authors.
Advanced Powder Technology | Year: 2017

The hydrodynamics of solid-liquid suspension process in a stirred tank with a dual rigid impeller, a dual rigid-flexible impeller, and a dual punched rigid-flexible impeller were investigated using computational fluid dynamics (CFD) simulation. A classical Eulerian-Eulerian approach coupled with standard k-ε turbulence model was employed to simulate solid-liquid turbulent flow in the stirred tank. The multiple reference frame (MRF) approach was used to simulate impeller rotation. The effects of impeller type, impeller speed, flexible connection piece width/length of dual rigid-flexible impeller, aperture size/ratio of dual punched rigid-flexible impeller, particle diameter, and liquid viscosity on the homogeneity degree of solid-liquid system were investigated. Results showed that the homogeneity degree of solid-liquid system increased with an increase in impeller speed. A long and wide flexible connection piece. was conductive to solid particles suspension process. Larger particle diameter resulted in less homogenous distribution of solid particles. An increase in liquid viscosity was beneficial to maintain solid particles in suspension state. The optimum aperture ratio and aperture diameter were 12% and 8. mm, respectively, for solid particles suspension process. It was found that dual punched rigid-flexible impeller was more efficient in terms of solid particles suspension quality compared with dual rigid impeller and dual rigid-flexible impeller under the same power consumption. © 2017 The Society of Powder Technology Japan.


Gu D.,Chongqing University | Gu D.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Liu Z.,Chongqing University | Liu Z.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 6 more authors.
Chemical Engineering and Processing: Process Intensification | Year: 2017

The mixing performance of solid-liquid system was investigated in a stirred tank with a double rigid impeller, a double rigid-flexible impeller, a double punched rigid-flexible impeller, and a double punched rigid-flexible impeller coupled with a chaotic motor. The effects of the impeller types, the flexible connection piece width/length, the aperture size/ratio, and the variable/constant speed periods were investigated. The mixing performance was characterized by the largest Lyapunov exponent (LLE) and axial local solid concentration profile. The results indicated that the double punched rigid-flexible impeller and chaotic motor could enhance the LLE value of solid-liquid mixing system on the basis of the double rigid-flexible impeller and traditional motor under the same power consumption. The variation in solid homogeneous degree was in good agreement with that of LLE. It was found that the double punched rigid-flexible impeller coupled with a chaotic motor could further improve the solid suspension quality and energy efficiency compared with the double rigid impeller or double rigid-flexible impeller coupled with a traditional motor in the solid-liquid mixing process. © 2017 Elsevier B.V.


Qiu Y.,Chongqing University | Qiu Y.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Du J.,Chongqing University | Du J.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | And 6 more authors.
Journal of CO2 Utilization | Year: 2017

The size tunable nano-Bi catalyst was fabricated via electroreduction of di-halogen bismuth oxyhalide (BiOX0.5Y0.5, X, Y=Cl, Br, I) and applied in CO2 electrochemical conversion to fomate. The nano-Bi particle size was controlled by changing with the halogen species used in precursors. A significant size effect on electrochemical active surface area (SE) and current density, as well as faradaic efficiency for formate was observed. The nano-Bi derived from precursor BiOCl0.5Br0.5 possessed minimum particle size of 10 nm and exhibited electrochemical active surface area (SE) of 4.63 cm2 mg-1. With the optimal precursor loading amount of 0.75 mg cm-2, the maximum Faradaic efficiency found for formate was 98.4% at -1.6 V (vs. SCE) with the desirable stability of 14 h, that is 92.7% and 86.2% corresponding to the nano-Bi electrode derived from BiOI0.5Br0.5 and BiOCl0.5I0.5, respectively. Characterization analysis revealed that the prepared catalyst film was composed of Bi3+ and Bi0, and the ratio of Bi0 to Bi3+ was closely related to the halogen species in precursors. The dominant exposed (012) plane of nano-Bi over electrode revealed the intrinsic property of the size controllable catalytic activity. The Tafel analysis suggested that the formation of surface-absorbed species via one electron transferring mechanism would be the initial rate determining step over the nano-Bi electrocatalyst for CO2 electrocatalytic reduction. © 2017 Published by Elsevier Ltd.


Peng H.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Peng H.,Chongqing University | Liu Z.,Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization | Liu Z.,Chongqing University | And 2 more authors.
Water Science and Technology | Year: 2017

Melamine, possessing three free amino groups and three aromatic nitrogen atoms in its molecule, has great potential as an adsorbent for metal ions. We investigated three impact factors of the adsorption process: the initial pH of the vanadium solution, contact time and reaction temperature. The adsorption kinetics could be accurately described by the pseudo-second-order kinetic model. Langmuir and Freundlich models fitted well with the experimental equilibrium data, and the maximal adsorption capacity was found to be 1,428.57 mg vanadium/g melamine, and the Freundlich model showed the adsorption is privilege type. © IWA Publishing 2017.


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.


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


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.
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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