Enhancement of the adsorption capacity of Fe-clay by bioleaching and activation of Fe sites

This study presents how the bioaccessibility and biotransformation of Fe- oxides present in two different Fe rich clay samples influenced their sorption properties. The bentonite and kaolin were bioleached by heterotrophic indigenous bacteria for 15 and 30 days and following treated by 1 M and 6 M hydrochloric acid. By bioleaching, only slight content of Fe was removed from the natural samples, but content of hardly soluble Fe oxides decreased and amorphous oxide- hydroxide increased. This transformation related with decrease in value of specific surface area and total pore volume, as well as with morphological and pore changes of studied clays. After 30 days of bioleaching process, bioleached samples proved better adsorption parameters for the AsV and SbV adsorption in comparison to natural samples. The sorption efficiency of AsV/SbV adsorption on bioleached materials reached up to 95-99%, at which the bentonite was more sensitive to bioleaching.