STUDY OF Cu(II) ADSORPTION BY BENTONITE AND FOLLOWING REGENERATION BY BIOLEACHING

Abstract

The natural bentonite and bentonite/iron oxide composite were used as sorbents of Cu(II). Theirsorption properties were examined under the different conditions such as pH of the solution, initialmetal ion concentration. The bentonite removed 71 % Cu(II) while composite 90 %. Their maximumadsorption capacities were 34.1 and 44.4 mg Cu(II) g-1, respectively. The chemical regeneration ofcomposite sorbent by organic acids (oxalic, citric) led to partial Cu(II) dissolution. The hydrochloricacid caused its structural destruction. For the bacterial regeneration, the sorbents were inoculated withheterotrophic indigenous bacteria. After 10 days the bacteria released approximately 80 % of loadedCu(II), leaving the sorbents stable. Longer treatment and higher concentration of metal cations causedthe reverse sorption of Cu(II) by bacteria. The regenerated sorbent was successfully repeatedly used forthe Cu(II) adsorption.