Chromium removal from water and tannery effluent with Cucurbit[6]uril

Chromium is one of the most pernicious metals present in some effluents, and its removal is mandatory during water treatment. Different methodologies for decontamination have been investigated, but some of them have high cost and can generate toxic waste. Here, we investigated the potential of cucurbit[6]uril (CB[6]) for the removal of Cr in water and tannery effluents. We observed decreases in Cr concentrations in samples containing from 10 to 50 mg L-1 within 8 h, the largest of which (25 times of the initial concentration) was observed for concentrations of 50 mg L-1. Adsorption follows a pseudo-second-order model indicating complexation of ions with CB[6], and higher concentrations lead to higher initial sorption rates. With a tannery effluent sample, CB[6] can remove up to 73% of chromium without any pretreatment. Therefore, CB[6] emerges as a promising sorbent of Cr ions for water treatment.