Biomass bagasse-based hyperbranched adsorbent for the complete removal of low-level Cr(VI)

A biomass bagasse-based hyperbranched adsorbent (BF/HBPA) with high amino density was synthesized using epichlorohydrin (ECH) to cross-link hyperbranched polyamine (HBP-NH 2 ) with bagasse fibre powder (BF). Using this kind of “cross-linking” procedure to synthesize the bagasse-based hyperbranched adsorbent could overcome the disadvantages of the low amino density in the stepwise grafting process, avoiding the requirement of strict preparation conditions and a complicated synthesis process. Thus, the as-prepared BF/HBPA could completely remove low-level Cr(VI) (1.6 mg/L), and showed an outstanding adsorption capacity (330.7 mg/g) for Cr(VI) at high Cr(VI) concentrations (108.3 mg/L) under 30 °C and pH value of 2. BF, as the framework of BF/HBPA cross-linking network, enhanced the adsorption rate (arrived at adsorption equilibrium in 15 min) for Cr(VI) on BF/HBPA. Moreover, BF/HBPA showed a promising regeneration property. After reusing for 10 cycles, the removal rate of BF/HBPA was maintained above 96%. The adsorption mechanism of physical electrostatic adsorption, chemical chelating adsorption and oxidation-reduction were all attributed to the complete removal of low-level Cr(VI) to the Safe Drinking Level (US EPA) (0.05 mg/L).