PI Hui-yu, CHEN Tian-hu^*, ZHOU Yue-fei, XIE Qiao-qin

(Laboratory of Nanominerals and Environmental Material, School of Resources & Environmental Engineering, Hefei University of Technology, Hefei 230009, China)

Abstract: The nano-micron multi-level pore structural granular material with hematite as the main phase was obtained by thermally activating of limonite, and used to simulate the purification of As(Ⅲ)-containing groundwater. The effects of thermal activation temperature, solution pH, As(Ⅲ) concentration, reaction temperature, and adsorption time on the removal of As(III) in water by thermally activated limonite were investigated in the static experiments, and the reaction kinetics and thermodynamic parameters were calculated. Characterizations of the solid product after the reaction were analyzed to explore the mechanism of As(III) removal in water over the thermally activated limonite. The results showed that the hematite derived from the thermal activation of limonite at 300 ℃ had the smallest crystal size (2.7 nm) and the largest specific surface area (107.4 m2/g). When the initial concentration of As(III) was 1 mg/L, slightly effect of the pH in the range of 2－7 on the removal of As(III) by thermally activated limonite was observed, and the As(III) removal were all above 98%. The reaction parameters indicated that the reaction followed the quasi-second-order kinetic equation and the Langmuir adsorption isotherm model. It was found that the thermally activated limonite possessed the adsorption and catalytic oxidation ability for As(Ⅲ) removal, and the manganese oxides in the material significantly enhanced the removal of As(Ⅲ). Therefore, this nano-mineral functional material prepared by thermally activating of limonite had great application potential for the treatment of the arsenic polluted groundwater, and provided a new idea for the utilization of limonite.

Keywords: limonite; hematite; nano-micron pore; adsorption; oxidation

ACTA MINERALOGICA SINICA Vol. 40, No.6, 2020, page 701-708