Adsorption of Toxic Selenium Oxoanions on Surface-Modified Kaolins

Abstract

Se is a trace element and an important micronutrient. At higher concentrations it may become a serious threat for the environment and human health. Se occurs in nature in organic or inorganic compounds (SeO₃^2–, SeO₄^2–). The toxic compounds can be removed from water by adsorption on aluminosilicates (kaolins, bentonites, zeolites). The aim of this work was the preparation of new low-cost sorbents based on kaolins and determination of their stabi­lity. The adsorbents were prepared by treatment of kaolin with Fe²⁺ or Al³⁺ solution yielding mesoporous amorphous Fe^III or Al^III oxides/hydroxides. The obtained materials were selective adsorbents of Se^IV in water. The batch sorption was performed with 10–1500 mg l^–1 aqueous Se solutions and evaluated using a Langmuir model. The removal of Se using the Al-treated kaolin was more effective than its Fe analog.