MECHANISM OF ALUMINUM INTERFERENCE ON URANIUM BIOSORPTION BY RHIZOPUS-ARRHIZUS

Uranium competitive uptake experiments by Rhizopus arrhizus were carri ed out at three different solution pH levels and in the presence of di fferent concentrations of competing aluminum ions in order to examine the competing ion effect. The colon effect became more pronounced as t he colon concentration in solution and pH level increased. A prelimina ry examination of the effect of aluminum on the rate of uranium uptake was also completed. Results showed that the presence of aluminum does not interfere with the kinetics of uranium uptake by R. arrhizus. Ele ctron microscopic and energy dispersive X-ray analyses were also perfo rmed on samples of the biomass. The combination of spectral data and t he information from the equilibrium studies and the kinetic studies su ggested that aluminum interferes with the uranium biosorptive uptake c apacity of R. arrhizus by the precipitation of a metastable amorphous hydroxy polymeric precipitate through a mechanism we refer to as steri c competition. (C) 1997 John Wiley & Sons. Inc.