Ferrous sulfide supported on modified diatomite for the removal of Cr(VI): Performance and mechanism
Hao Luo, Fenglian Fu, Bing Tang
Abstract
How to remove hexavalent chromium (Cr(VI)) from aqueous solution has always been a challenging problem in the environmental field. In this study, a novel composite of oxalic acid modified diatomite (DT) supported ferrous sulfide (FeS) was prepared by hydrothermal synthesis . The experiment results showed that the oxalic acid modified diatomite retained its original porous structure and possessed rougher surface, which could be used as a good loading/dispersing material to provide more adsorption sites. The composite material FeS/DT (the mass ratio of ferrous sulfide to modified diatomite is 1:1) can reduce more than 99 % of Cr(VI) to Cr(III) within 20 min, and Cr(III) can be adsorbed to the surface of diatomite. FeS/DT had a good adsorption and reduction effect at initial pH 3.0–9.0. The experimental results were in agreement with pseudo-second-order kinetic model and Langmuir isotherm adsorption model. Maximum adsorption capacity of FeS/DT for Cr(VI) can reach 141.6 mg/g. The reasons for the excellent reduction and adsorption ability of the FeS/DT were the reducibility of ferrous sulfide and porous structure of modified DT. This study revealed the reaction mechanisms of FeS/DT with Cr(VI), and demonstrated the feasibility of FeS/DT in the removal of Cr(VI) from water environment.