Biosorption of uranium(VI) by Aspergillus fumigatus

Aspergillus fumigatus removed uranium(VI) very rapidly and reached equilibrium within 1 h of contact of biomass with the aqueous metal solution. Biosorption data fitted to Langmuir model of isotherm and a maximum loading capacity of 423 mg U g(-1) dry wt was obtained. Distribution coefficient as high as 10,000 (mg U g(-1))/(mg U ml(-1)) at a residual metal ion concentration of 19 mg l(-)1 indicates its usefulness in removal of uranium(VI) from dilute waste streams. Optimum biosorption was seen at pH 5.0 and was independent of temperature (5-50 degrees C ). Initial metal ion concentration significantly influenced uptake capacity which brought down % (w/w) uranium(VI) removal from 90 at 200 mg U l(-1) to 35 at 1000 mg U l(-1). Presence of 0.84 mmol Fe2+, Fe3+, Ca2+ and Zn2+ had no effect on uranium(VI) biosorption unlike Al3+ (0.84 mM) which was inhibitory.