[Biomass of Rhizopus oligosporus as an adsorbent for metal ions]. / Biomasa de Rhizopus oligosporus como adsorbente de iones metálicos.

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+.