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Adsorption behavior of poly(ethylene oxide) on kaolinite: Experimental and molecular simulation study

Wang Tingting, Wang Jing, Zhang Mingqing, Liu Bingfeng, Zhang Haijun, Li Jihui

Physicochemical Problems of Mineral Processing

2024

Vol. 60, iss. 2

art. no. 185900

Poly(ethylene oxide) (PEO) adsorption behavior on kaolinite surfaces in an aqueous solution was investigated through experiments, the density functional theory (DFT), and molecular dynamics (MD) simulations. The experimental results showed that as the PEO concentration increased, the adsorption capacity first increased then slightly decreased and the turbidity change was opposite. The adsorption isotherm on the kaolinite surface was more suitable for the Langmuir model and valid for single-layer adsorption. The results of simulations showed that the PEO chains extended along the two basal surfaces of kaolinite or were partly adsorbed, forming loops and tails that caused most of the particles to flocculate, contributing to the turbidity lowering. When the number of PEO chains was excessive, their self- and inter-aggregation occurred with some PEO far from the surface, and the turbidity increased. On the kaolinite (001) surface, the hydrogen bonds between the PEO ether O and the hydroxyl groups constituted the main interaction mechanism. However, the hydrophobic force of the (CH2–CH2)–moiety of PEO might have dominated its adsorption on the (001̅) surface. The hydrogen bonds were stronger than the hydrophobic interactions.

Experimental and numerical study on the classification of a cyclonic field in a flotation column

Li Xiaoheng, Li Xiao, Yan Xiaokang, Wang Lijun, Zhang Haijun

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 3

421--431

The cyclonic-static micro-bubble flotation column (FCSMC) performs well in fine mineral flotation. Compared to traditional flotation columns, its design innovatively introduces a cyclonic structure. The separation of middling and tailing occurs in the cyclonic flow field induced by a cyclonic reversal cone. In this study, the particle size distribution analysis and computational fluid dynamics (CFD) simulations were conducted to reveal the particle distribution law and the classification mechanism in cyclonic flow fields under different circulation pressures. The results showed that particle size showed the same distribution tendency as tangential velocity in the radial direction: both increase from the center and decrease around the wall. As circulation flux increased, the tangential velocity increased, and the particle size differences in the radial direction also increased. The position of the largest particles will move to outside as the largest value of tangential velocity migrates the outward in the radial direction. According to the particle size distribution of the feed, it can be adjusted to the flow field to change the particle distribution, thereby improving the efficiency of separation. This study has an important guiding significance for column design and adjustment of the operating parameters of the flotation process.