Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
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Hollow Multishell-Structured TiO2/MAPbI(3) Composite Improves Charge Utilization for Visible-Light Photocatalytic Hydrogen Evolution br
No full textInterfacial photo generated charge separation and trans-port have demonstrated great influence on photocatalytic performance.Herein, the composite photocatalysts of methylammonium lead iodideperovskite (MAPbI3) in TiO2with a hollow multishell structure(HoMS) are designed and synthesized. The results indicate that theheterogeneous interface within the MAPbI3/Pt/TiO2-HoMS can helpenhance the separation of photogenerated charges. HoMSs assembledwith multiple shells can not only support large surfaces available forbuilding a heterogeneous interface and photocatalytic reactions but alsoimprove the light absorption capability of photocatalysts. Besides, thethin shell structure can also reduce the transmission distance of carriersso as to hinder charge recombination and improve charge utilization. Asa result, samples of MAPbI3/Pt/triple-shelled TiO2hollow structuredisplayed a H2yield of 6856.2 mu mol h-1g-1under visible light, which is greatly better than that of bare MAPbI3(268.6 mu mol h-1g-1
Microbial pretreatment of microfine-grained low-grade zinnwaldite tailings for enhanced flotation to recover lithium and rubidium resources
No full textThe accumulation of large amounts of refractory zinnwaldite in tailings pond in Hunan (China) implies a waste of the rare lithium and rubidium resources and also induces serious environmental problems. In the present study, the microbial pretreatment was introduced prior to the desliming and flotation processes. The silicate bacteria "LM-1 ", isolated from deep-sea sediments, was used to decompose and erode the minerals. This procedure will solve the problem of difficult sorting of the tailings in a more efficient and environmentally friendly way. Through flotation tests and mineral surface analysis, we derived the optimum pretreatment and flotation solution and we discuss application processes that will enhance the flotation effectiveness. The test results showed that the pretreatment with "LM-1 " caused an enlargement of the cleavage plane {001} on the surface of the ore grains and an increase of the content of the cleavage plane {001} throughout the raw ore. Therefore, the adsorption capacity of the collector increased, and the selectivity was enhanced, which largely improved the floatability of the zinnwaldite. A good index of 2.89% Li2O grade with 71.68% recovery and 0.59% Rb2O grade with 80.42% recovery was obtained for the concentrate. Compared to conventional flotation processes, the more efficient release of potassium and desilication through "LM-1 " not only avoids the high energy consumption and serious sliming caused by fine grinding of minerals, but also effectively improves the separation results
Modeling partition coefficient of liquid droplets impacting on particles by direct numerical simulation
No full textLiquid partition coefficient, defined as the proportion of the liquid volume covered on particle surface to that in bulk phase, is a key parameter in the simulation of liquid-injected fluidized beds. To develop the sub-grid model for liquid partition coefficient as a function of local hydrodynamics, a two-dimensional Volume-of-Fluid (VOF) simulation was conducted to directly resolve droplets impinging, wetting and spreading on particles in a box. The model was first validated by the experiments in literature on the spreading diameter of a droplet impinging on a single particle. Then for a system of multiple droplets particles impinging, we investigated the effects of Weber number, droplet-to-particle (DTP) ratio and particle volume fraction on several characteristic parameters, e.g., ratio of liquid area adhered to particles to the total liquid area, liquid film thickness, the percentage of wetted particle surface area and liquid holdup. All these parameters decrease with increasing Weber number when We = 10 ti 370, and then gradually stabilize. Higher particle volume fraction increases the collisional frequency of droplets and particles, and therefore the ratio of liquid area adhered to particles to the total liquid area. By contrast, DTP is not the dominant factor in liquid partition. Finally a correlation for liquid partition coefficient is proposed as a function of droplet Weber number and particle volume fraction. It may serve as a sub grid model for CFD-DEM or multifluid models in simulation of large-scale liquid-injected fluidized beds.(c) 2022 Elsevier Ltd. All rights reserved
<p>Recycling of full components of polyester/cotton blends catalyzed by betaine-based deep eutectic solvents</p>
No full textThe development of an environmental methodology for polyethylene terephthalate (PET) degradation and separation from cotton is significant for the full utilization of waste polyester/cotton blends (PCBs). Therefore, it is crucial to find a catalyst that can efficiently catalyze PET degradation and completely separate from cotton. In this work, betaine based deep eutectic solvents (DESs) were first synthesized and innovatively used for selective degradation of PET fibers from PCBs. As a result, PET fiber was degraded completely, a purified monomer bis (2-hydroxyethyl terephthalate) (BHET) with a yield of 85% was obtained that could be repolymerized to produce PET, and 95% of the cotton was recycled and maintained its original structural integrity. Meanwhile, the synergistic mechanism was also proposed by in-situ IR, H-1-NMR and DFT calculations. This work provides a new approach to recycle full components of waste PCBs
Design of Refining Slag Based on Structural Modifications Associated with the Boron Removal for SoG-Si
No full textSolar grade silicon (SoG-Si) is the core material of solar cells. The removal of boron (B) has always been a challenge in the preparation of high purity Si. Slag refining has always been considered as one of the effective methods to remove B, but the design of refined slag has been limited by the cognition of the relationship between slag structure and impurity removal, and can only rely on the apparent basicity and oxygen potential adjustment of slag based on a large number of conditional experiments. In order to clarify the B removal mechanism of slag refining from Si, nuclear magnetic resonance (NMR) and Raman vibrational spectroscopy were used to investigate in detail the behavior and state of B and aluminum (Al) in the SiO2-CaO-Al2O3-B2O3 slag. The role of the degree of B-Si cross linking on the B activity in slag was highlighted by comparing the partition ratio (L-B) between slag and Si. Q(2) structural unit of slag is an important site for capturing B. BO4 (1B, 3Si) species is the main form of connection between B and silicate networks, which determines the activity of B in the slag. The addition of Al2O3 into SiO2-CaO slag can change the relative fraction of Q(2) and BO4 (1B, 3Si). Increasing Al2O3 content from 0 to about 20 wt% can lead to the overall increase of Q(2) population, and a tendency to decrease first and then increase of BO4 (1B, 3Si) fraction under both basicity conditions (0.6 and 1.1). When Al2O3 content is less than 10 +/- 1 wt%, the decrease of BO4 (1B, 3Si) population plays a major role in deteriorating the connectivity between B and aluminosilicate network, which leads to a higher activity of B. When the Al2O3 content is greater than 10 +/- 1 wt%, B is incorporated into the silicate network more easily due to the formation of more Q(2) and BO4 (1B, 3Si), which contributes to a rapid decline in activity of B in slag
