The presence of clay minerals in coal tailings leads to a significant deterioration during the dewatering process. In this study, a cationic surfactant, stearyl trimethyl ammonium chloride (STAC), was considered to enhance the dewatering efficiency of coal tailings. The effect of STAC on coal tailing dewatering was evaluated by the filtration test. Results indicate that STAC can reduce filter cake moisture by increasing the hydrophobicity of particles, decreasing the surface tension of the filtrate, as well as neutralizing the associated charge. Furthermore, to investigate the interactions between STAC and coal tailings, the morphology of adsorbed STAC, interfacial adsorption structure, and dynamic behavior of water molecules were determined by atomic force microscopy (AFM) and molecular dynamics (MD) simulations on an atomic scale. AFM results revealed that the morphologies of STAC adsorbed on coal and kaolinite surfaces differed, owing to distinct interaction mechanisms. The adsorption of STAC on the kaolinite 001 surface is more uniform than on the 00 1 - face and is predominantly based on monolayer adsorption through electrostatic interactions and hydrogen bonding. The MD simulation results suggest that the adsorption of STAC significantly inhibits the attachment of water molecules on coal and kaolinite surfaces. The nitrogen atoms of STAC were adsorbed to the particle surface, such that its alkyl chains were oriented towards water, thereby weakening the interaction between the particles and water. The above findings indicate that the addition of STAC can improve the hydrophobicity of coal and kaolinite effectively and thus, enhance the dewatering performance of coal tailings.
Li Shun,Niu Airong,Lan Cuixia,Xu Xuanming,Sun Shukai,Xuan Chao,Zhao Peng,Tian Qingwu,Zhou Tingting
A novel electrochemical sensor of multi-walled carbon nanotube (MWCNT) and stearyl trimethyl ammonium chloride (STAC) modified acetylene black paste electrode (AB-PE) was successfully established. An AB/MWCNT/STAC-paste electrode was constructed using the AB electrode with MWCNT and STAC as the electrochemical sensor materials. The performance of the prepared sensor was characterized by electrochemical impedance spectroscopy and cyclic voltammetry. Some factors, such as sensor composition, adsorption, and detection conditions, which affect the property of the sensor, were investigated in detail. The results demonstrated that the prepared sensor has satisfactory selectivity, repeatability, and stability for methotrexate (MTX) detection. The linear range of the method for MTX detection was 0.02–8.0 μM with a limit of detection (LOD) of 1.81 nM. Finally, the sensor was successfully used for detecting the MTX concentrations in the samples of serum and saliva. The prepared sensor could be a fresh platform for the swift and accurate MTX detection in clinical samples. Graphical abstract
A two-stage leaching process, namely, high-pressure acid leaching-atmospheric acid leaching, was used to treat laterite ores under mild conditions. The leaching ratio of Ni was low because of adsorption and incomplete leaching. In this work, surfactants were used as additives to boost the leaching ratio of Ni. The effect of surfactant type (cationic, anionic, and nonionic surfactants) on the leaching ratio of Ni was investigated. Leaching results showed that stearyl trimethyl ammonium chloride (STAC) apparently increased the leaching ratios of valuable metals. The variation in the physicochemical properties of the lixiviant and the residue improved the leaching ratio of Ni in the presence of STAC. Kinetics analysis indicated that the leaching process was controlled by chemical reaction.
危险品化学品经营许可证（带存储）