Cr(VI) removal by cellulose-based composite adsorbent with a double-network structure

A cellulose-based composite adsorbent (PEI-PAM-CF) was fabricated via a facile cross-linking of polyethyleneimine/polyacrylamide (PEI/PAM) and cellulose using epichlorohydrin as the cross-linker. It possessed a double-network structure and emitted blue fluorescence. Compared with the control samples (PEI-CF and PAM-CF), the PEI-PAM-CF showed a synergy effect for the Cr(VI) removal. It can effectively remove Cr(VI) at low concentration with no structure destroyed for the adsorbent. Other coexisting anions (NO 3 - , Cl - , H 2 PO 4 - and CH 3 COO - ) and cations (Na + , K + , Mg 2+ , Ca 2+ and Cr 3+ ) had no significant effect on Cr(VI) removal except SO 4 2- . After five adsorption/desorption cycles, the Cr(VI) removal only decreased with a loss of 7%, suggesting that the PEI-PAM-CF had good regeneration performance. Most importantly, the electrostatic adsorption mechanism between Cr(VI) and the PEI-PAM-CF was revealed by a reversible fluorescence “on-off-on” phenomenon and the DFT calculation. The adsorption sites on the PEI-PAM-CF were attributed to the amino groups of the PEI and PAM . Hence, the PEI-PAM-CF was potential for the treatment of Cr(VI)-containing wastewater at low concentration.