Structural design of a cellulose-based hyperbranched adsorbent for the rapid and complete removal of Cr(VI) from water

Abstract

• Cellulose-based hyperbranched adsorbent was designed by the cross-linking strategy. • The adsorbent could completely remove low level of Cr(VI) (1.02 mg/L) within 2 min. • The 3-D dendritic structure of adsorbent endowed rapid removal property for Cr(VI). • One-step rapid conversion strategy insured high reagents conversion rate (≥99%). • The high amine density and efficient diffusion dynamics of adsorbent were balanced. To solve the problem that cellulose-based adsorbents cannot remove Cr(VI) from water to the drinking water standard (US EPA, 0.05 mg/L) within 5 min due to imbalance of the high amine density and high-efficiency diffusion dynamics. A cellulose-based hyperbranched adsorbent (MCC/HBPA-0.88) was designed and prepared via cross-linking with microcrystalline cellulose (MCC) and amino-terminated hyperbranched polymers (HBP-NH 2 ). This strategy for liquid–solid phase one-step rapid conversion could effectively increase the conversion rate of the reactants (above 99%). The cellulose-based hyperbranched adsorbent possessed high amino density (10.63 mmol/g), high swelling rate (341%) and three-dimensional hyperbranched structure. It could rapidly and completely remove Cr(VI) from water with a low level of Cr(VI) (1.02 mg/L), and the residual Cr(VI) concentration satisfied the safe drinking level standards within 1 min, which exceeds the absorption rates of cellulose-based adsorbents that have been reported in the literatures.