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

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-NH2). 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.