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Mesoscopic study of the formation of pseudomorphs with presence of chemical fluids
Li Chen,Qinjun Kang,Hailin Deng,J. William Carey,WenQuan Tao 한국지질과학협의회 2014 Geosciences Journal Vol.18 No.4
A numerical approach is developed to simulate theformation of pseudomorphs with presence of chemical fluids at themesoscopic scale. This approach consists of the lattice Boltzmannmethod (LBM) for transport of chemical species in the pore space,a chemical reaction model including basic kinetics of the coupleddissolution and precipitation reactions, and a mesoscopic modelfor nucleation and crystal growth. Our study confirms the mechanismof the solution chemistry-driven interface-coupled dissolution-precipitation for the formation of pseudomorphs and identifiesseveral sources for the generation of porosity in the pseudomorphs. We demonstrate that epitaxial precipitation is not necessary andrandom crystal growth may be more favorable for pseudomorphs. We show that the difference of precipitation barrier on the surfaceof the primary and secondary minerals should not be too large. Otherwise only the rim of the primary phase is roughly preserved.
Wang, Wenquan,Zhang, Li-Xiang,Yan, Yan,Guo, Yakun Techno-Press 2012 Coupled systems mechanics Vol.1 No.4
This paper presents a fully coupled three-dimensional solver for the analysis of interaction between pulsatile flow and large deformation structure. A partitioned time marching algorithm is employed for the solution of the time dependent coupled discretised problem, enabling the use of highly developed, robust and well-tested solvers for each field. Conservative transfer of information at the fluid-structure interface is combined with an effective multi-predict-correct iterative scheme to enable implicit coupling of the interacting fields at each time increment. The three-dimensional unsteady incompressible fluid is solved using a powerful implicit time stepping technique and an ALE formulation for moving boundaries with second-order time accurate is used. A full spectrum of total variational diminishing (TVD) schemes in unstructured grids is allowed implementation for the advection terms and finite element shape functions are used to evaluate the solution and its variation within mesh elements. A finite element dynamic analysis of the highly deformable structure is carried out with a numerical strategy combining the implicit Newmark time integration algorithm with a Newton-Raphson second-order optimisation method. The proposed model is used to predict the wave flow fields of a particular flow-induced vibrational phenomenon, and comparison of the numerical results with available experimental data validates the methodology and assesses its accuracy. Another test case about three-dimensional biomedical model with pulsatile inflow is presented to benchmark the algorithm and to demonstrate the potential applications of this method.
Room-temperature power factor of CuAlO2 composite tablets enhanced by MWCNTs
Ma Lingxiao,Dong Chenhao,Li Wenquan,Su Qing,Zhou Jinyuan,Xie Erqing,Lan Wei 한국물리학회 2022 Current Applied Physics Vol.33 No.-
CuAlO2 with high theoretical thermoelectric performance has potential applications in thermal energy conversion. Herein, multi-wall carbon nanotubes (MWCNTs)/CuAlO2 composite tablets are prepared by using different amounts of MWCNTs and solid paraffin binder, where MWCNTs served as a conductive agent and rendered three orders of magnitude increase in electrical conductivity. Seebeck coefficient of the composites was reduced with increasing MWCNTs content. Consequently, an optimal room-temperature thermoelectric power factor (PF) of 1.31 μW m 1K 2 has been rendered by MWCNTs/CuAlO2 composite tablet with 1 wt % MWCNTs. Moreover, PF value increased with increasing temperature after a slight decrease at 333 K, which can be ascribed to the modulation of electrical conductivity. Current work provides an effective strategy to improve thermoelectric performance of CuAlO2 materials.
Synthesis of Cd1-xZnxS/K4Nb6O17 Composite and its Photocatalytic Activity for Hydrogen Production
Yinghua Liang,Meiyi Shao,Li Liu,Jinshan Hu,Wenquan Cui 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.4
Cd1-xZnxS-sensitized K4Nb6O17 composite photocatalysts (designated Cd1-xZnxS/K4Nb6O17) were prepared via a simple deposition-precipitation method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), N2 sorption, ultraviolet–visible light diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence measurements (PL), and X-ray photoelectron spectroscopy (XPS). The Cd0.8Zn0.2S particles were scattered on the surface of K4Nb6O17, and had a relatively uniform size distribution around 50 nm. The absorption edge of K4Nb6O17 was shifted to the visible light region and the recombination of photo-generated electrons and holes suppressed after Cd0.8Zn0.2S loading. The Cd0.8Zn0.2S(25 wt %)/K4Nb6O17 composite possessed the highest photocatalytic activity for hydrogen production under visible light irradiation, evolving 8.278 mmol/g in 3 h. Recyclability tests were performed, and the composite photocatalysts were found to be fairly stable. The mechanism of charge separation between the photogenerated electrons and holes at the Cd0.8Zn0.2S/K4Nb6O17 composite was discussed.
Liang, Yinghua,Shao, Meiyi,Liu, Li,Hu, Jinshan,Cui, Wenquan Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.4
$Cd_{1-x}Zn_xS$-sensitized $K_4Nb_6O_{17}$ composite photocatalysts (designated $Cd_{1-x}Zn_xS/K_4Nb_6O_{17}$) were prepared via a simple deposition-precipitation method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), $N_2$ sorption, ultraviolet-visible light diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence measurements (PL), and X-ray photoelectron spectroscopy (XPS). The $Cd_{0.8}Zn_{0.2}S$ particles were scattered on the surface of $K_4Nb_6O_{17}$, and had a relatively uniform size distribution around 50 nm. The absorption edge of $K_4Nb_6O_{17}$ was shifted to the visible light region and the recombination of photo-generated electrons and holes suppressed after $Cd_{0.8}Zn_{0.2}S$ loading. The $Cd_{0.8}Zn_{0.2}S$(25 wt %)/$K_4Nb_6O_{17}$ composite possessed the highest photocatalytic activity for hydrogen production under visible light irradiation, evolving 8.278 mmol/g in 3 h. Recyclability tests were performed, and the composite photocatalysts were found to be fairly stable. The mechanism of charge separation between the photogenerated electrons and holes at the $Cd_{0.8}Zn_{0.2}S/K_4Nb_6O_{17}$ composite was discussed.
Jinshan Hu,Pengfei Zhang,Jifang Cui,Weijia An,Li Liu,Yinghua Liang,Qingbin Yang,Hongjun Yang,Wenquan Cui 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.84 No.-
To achieve rapid separation of electron-hole pairs and improve photocatalytic degradation activity, theFe-g-C3N4 reduced graphene hydrogel (rGH/Fe-g-C3N4) with a 3D network structure was fabricated viathe hydrothermal method. Using visible light irradiation, H2O2 was added to form a photocatalysis-Fenton synergy system. The results showed that the synergistic degradation rate constant of 10% rGH/Feg-C3N4 was 52% higher than that of the multiphase Fenton reaction and 1.5 times higher than that of theFe-g-C3N4. In the seventh cycle, the catalytic efficiency was still as high as 86.9%. Based on the optimizedconditions from phenol degradation, the system was further applied to coking wastewater treatment,and the degradation efficiency of TOC and COD in 60 min reached 66.3% and 68.1%, respectively. Such highand stable degradation performance was ascribed to the synergy effect of photocatalysis and Fenton. Because of the photogenerated electrons not only can promote the Fe3+/Fe2+ cycle, accelerate thedecomposition of H2O2, but also can quickly transfer to graphene and directly decompose H2O2 to formOH. Thus, a large amount ofOH were generated through the two different channels, which greatlyimprove the degradation efficiency. Furthermore, rGH/Fe-g-C3N4 can be regenerated usingfilters withoutthe need for additional complicated processing. This work provides an effective strategy for the deeptreatment of industrial wastewater.