Adsorptive removal of Cr3+ from aqueous solutions using chitosan microfibers immobilized with plant polyphenols as biosorbents with high capacity and selectivity

A novel biosorbent was facilely prepared by immobilizing bayberry tannin (BT, a typical natural polyphenols) onto chitosan microfiber (CM). The as-prepared CM-BT adsorbent featured to a well-defined microfibrous morphology and highly distributed adsorption sites, which was highly efficient and selective for the adsorptive removal of Cr 3+ from aqueous solutions. Based on batch experiments, the adsorption of Cr 3+ on CM-BT was pH-dependent, and the optimized adsorption pH was determined to be 5.5. The adsorption capacity of CM-BT to Cr 3+ was high up to 20.90   mg/g. The co-existing cations, such as Mg 2+ , Ca 2+ , Fe 3+ and Cu 2+ , exhibited no significant influences on the adsorption of Cr 3+ on CM-BT. The adsorption kinetics were well fitted by the pseudo-second-order rate model ( R 2   >   0.99) while the adsorption isotherms were well described by the Langmuir model ( R 2   >   0.98). Importantly, CM-BT was effective for the continues treatment of low concentration Cr 3+ (2.0   mg/L) contaminated wastewater. Before reached the breakthrough point (5% of the initial Cr 3+ concentration, 0.1   mg/L), the treated volume was as high as 894 bed volume, manifesting the great potential of CM-BT in practical treatment of Cr 3+ contaminated wastewater.