Multiple active sites cellulose-based adsorbent for the removal of low-level Cu(II), Pb(II) and Cr(VI) via multiple cooperative mechanisms

A novel multiple active sites cellulose-based adsorbent (MCC/TEPAA-BCTTC) with a high density of multiple active adsorption sites (N, O, S) was prepared by using epichlorohydrin cross-linking microcrystalline cellulose (MCC) with tetraethylenepentamine (TEPA), followed by grafting with bis(carboxymethyl) trithiocarbonate (BCTTC). It was shown that the removal rates of MCC/TEPAA-BCTTC for Pb(II) (1 mg/L), Cu(II) (3 mg/L) and Cr(VI) (1 mg/L) reached 100 %, 98 % and 99 %, respectively, and the remaining concentration after adsorption reached the United States Environmental Protection Agency (US EPA) standards for Pb(II) and Cu(II) and the China integrated wastewater discharge standard for Cr(VI). These results indicate that the high removal rate of MCC/TEPAA-BCTTC for removing anionic and cationic heavy metal ions in low-concentration mixed heavy metal ions environments was mainly due to the high density of multiple adsorption sites that act via multiple cooperative mechanisms.