Adsorption of AsV in aqueous solutions on porous hematite prepared by thermal modification of a siderite - goethite concentrate

Abstract

Environmental contextArsenic in drinking water is a global environmental concern with serious effects on human health. We have developed a cheap and effective adsorbent, based on porous hematite, for removing arsenic from water. This material could be used in adsorption columns to remove arsenic from drinking water supplies. AbstractThe adsorption of AsV in aqueous solutions on porous hematite prepared by the thermal modification of a siderite–goethite concentrate has been studied. This study included the preparation and characterisation of the porous hematite and the adsorption of AsV on the modified concentrate. The experimental results showed that the thermal decomposition of the siderite–goethite concentrate was an efficient process to prepare porous hematite. The mechanism might be attributed to the dehydration of goethite and the decomposition of siderite during the thermal treatment, forming a large amount of micropores. It has been found that the adsorption capacity of AsV on the porous hematite in aqueous solutions was greatly improved to 8.94 mg g–1, compared with 1.07 mg g–1 from the original concentrate, and the adsorption rate was also increased approximately four times. The improvements might be due to the formation of micropores and mesopores and thus the increase of the surface area. The mechanism of the adsorption was attributed to chemical adsorption of AsV species on porous hematite in aqueous solutions. The adsorption was enhanced by increasing solution temperature and was strongly pH dependent.