title: Ammonium sulfide-assisted hydrothermal activation of palygorskite for enhanced adsorption of methyl violet.
abstract: Herein, palygorskite (PAL) was activated via a simple hydrothermal process in the presence of ammonium sulfide, and the effects of activation on the microstructure, physico-chemical feature and adsorption behaviors of PAL were intensively investigated. The hydrothermal process evidently improved the dispersion of PAL crystal bundles, increased surface negative charges and built more active -Si-O(-) groups served as the new "adsorption sites". The adsorption property of the activated PAL for Methyl Violet (MV) was systematically investigated by optimizing the adsorption variables, including pH, ionic strength, contact time and initial MV concentration. The activated PAL exhibited a superior adsorption capability to the raw PAL for the removal of MV (from 156.05 to 218.11mg/g). The kinetics for MV adsorption followed pseudo second-order kinetic models, while the isotherm and thermodynamics results showed that the adsorption pattern well followed the Langmuir model. The structure analysis of PAL before and after adsorption demonstrated that electrostatic interaction and chemical association of -X-O(-) are the prominent driving forces for the adsorption process.
authors.affiliation: Center for Eco-material and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of the Chinese Academy of Sciences, Beijing 100049, China. Electronic address: tianguangyan@licp.cas.cn.
authors.forename: Guangyan
authors.initials: G
authors.lastname: Tian
authors.affiliation: Center for Eco-material and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; R&D Center of Xuyi Palygorskite Applied Technology, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Xuyi 211700, China.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Wang
authors.affiliation: Center for Eco-material and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; R&D Center of Xuyi Palygorskite Applied Technology, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Xuyi 211700, China.
authors.forename: Yuru
authors.initials: Y
authors.lastname: Kang
authors.affiliation: Center for Eco-material and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; R&D Center of Xuyi Palygorskite Applied Technology, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Xuyi 211700, China. Electronic address: aqwang@licp.cas.cn.
authors.forename: Aiqin
authors.initials: A
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D004396:Coloring Agents / Q000737:chemistry*; D005840:Gentian Violet / Q000737:chemistry*; D007700:Kinetics; D017616:Magnesium Compounds / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D017616:Magnesium Compounds; D017655:Silicon Compounds; D013440:Sulfides; D014874:Water Pollutants, Chemical; C027711:ammonium sulfide; D005840:Gentian Violet; C026325:attapulgite
keywords: Adsorption; Hydrothermal; Methyl violet; Palygorskite