[Biomass of Rhizopus oligosporus as an adsorbent for metal ions].

The effect of different parameters on the adsorption of metal ions by Rhizopus oligosporus has been studied. The uranium sorption by dried biomass was rapid, reaching in 5 min around 95.% of the binding capacity. The uranium-binding capacity of the culture showed an inverse relation to the growth kinetic. The relationship between sorption and equilibrium concentration was similar to an adsorption isotherm. Using the Langmuir model, a maximum sorption capacity of 0.52 mmoles uranium/g dry biomass and an affinity constant of 101 l/mmol uranium at pH 4.15 were determined. The best capacity of the biomass to bind ions (UO2(2+), Cu2+, Cd2+ and Zn2+) was best at pH 4.5-5.5. By using hydrochloric acid as eluant a 18% uranium removal of the biomass-bound ions was obtained at pH 1.0. The presence of other cations inhibited uranium-binding in the following order: Cu2+ > Cd2+ > Zn2+ > Mg2+ > Ca2+.