Biosorption of metal ions using chitosan, chitin, and biomass of Rhizopus oryzae

The biosorptive capacity of dried biomass fungus Rhizopus oryzae Went & Prinsen-Geerlings for metal sorption was compared with commercially available sources of chitin, chitosan and chitosan cross-linked with benzoquinone. Initial pH of the metal solution significantly influenced metal uptake capacity. The optimum biomass/solution ratio for metal uptake in all systems was 1 g/L. The highest metal uptake values (137, 108, 58, and 124 mg/g, respectively, for copper, zinc, arsenic, and chromium) were achieved with chitosan (1 g/L, at pH 4) from initial metal concentrations of 400 mg/L. Decreases in mean metal concentrations from a simulated copper/zinc mine effluent were 73%, 14%, and 36% for copper, aluminum, and zinc, respectively, which corresponded to respective metal uptake values of 16, 11, and 21 mg/g. Sorption from a simulated gold mine effluent showed decreases in mean concentrations of aluminum, arsenic, and copper of 85%, 30%, and 92%, respectively, which corresponded to respective metal uptake values of 3.0, 6.0, and 1.6 mg/g. The observed decreases in copper levels to concentrations below 1 mg/L indicate potential for specific polishing applications. At low pH, R oryzae biomass was more resistant than was chitosan. Cross-linking with benzoquinone under alkaline conditions conferred stability to the chitosan biomass under low pH, but some reduction in sorption capacity was observed.

Duke Scholars

Author Joseph C. Nadeau Civil and Environmental Engineering