REUSE OF CERAMICS FOR HEAVY METALS REMOVAL FROM WASTEWATERS: SORPTION AND STABILIZATION

ABSTRACT

Heavy metals ions can be removed from industrial wastewaters by numerous methods, such are precipitation, electrolysis, electrodyalisis etc. Sorption, i.e. adherence of a dissolved specie on solid sorbent, may be a cost-effective alternative to these conventional methods, in case a low-cost material is used as sorbent. Heavy metals are well sorbed by zeolites, clay minerals, char coal, carbon nanomaterials or numerous biopolymers. In this research, waste ceramic was used as sorbent for heavy metals (Cu, Pb, Zn). The low-cost sorbents are not regenerated, but the spent sorbent, with adsorbed heavy metals, has to be stabilized/solidified in order to prevent leach out of the sorbed speciest, e.g. by help of Portland cement. Two series of immobilizates were tested – firstly the spent sorbents with above listed elements were mixed with Portland cement. In sake of comparison, the immobilizates with directly dosed oxides of respective metals were tested. The used sorbents with Cu and Pb, without any stabilization, are classified, according to their leaching behavior, as hazardous waste, while Zn as “other waste”. The cement stabilization reduced significantly the leaching. Concerning the sorbent effect on leaching, it was marked in Cu, while in Pb systems, the leached amount was comparable. Zn stabilization was very successful, while in Pb case, just moderate amount of sorbent can be dosed, otherwise the leaching is too intensive.

Keywords: recycling, ceramic, heavy metals removal, sorption, stabilization