The tolerance of Rhizopus arrihizus to U(VI) and biosorption behavior of U(VI) onto R. arrihizus

This work focused on U(VI) biosorption using suspended Rhizopus arrihizus. To understand the biosorption process, the tolerance of the strain to U(VI) and the effects of solution pH, initial U(VI) concentration, temperature, and contact time on U(VI) removal were investigated in batch systems. The results demonstrated that R. arrihizus can grow normally in 200 mg L−1 uranium-contained medium. Optimum biosorption was observed at solution pH 4.0 and the maximum biosorption capacity (112.2 mg g−1) was obtained at initial U(VI) concentration of 200 mg L−1. The biosorption process appeared to be temperature independent. Biosorption equilibrium was established within 90 min and the pseudo second-order model was found to fit accurately with the experimental data. FT-IR analysis and SEM morphology indicated that the structure of the strain remained integral after biosorption. Amino group plays an important role in the biosorption process, hydroxyl and carboxyl groups are also involved in U binding.