Isotherms, thermodynamic and mechanism studies of removal of low concentration uranium (VI) by Aspergillus niger

In order to develop an effective and economical method for removing low concentration radioactive wastewater of uranium, the biomass of ‘CMCC(F)-98003’ Aspergillus niger was investigated in a batch system. The maximum uranium adsorption capacity of 12.5 mg g⁻¹ was obtained at the initial uranium concentration of 0.75 mg L⁻¹. The biosorption data on a biomass concentration of 0.029 g L⁻¹ fitted well to the Freundlich isotherm with a correlation coefficient (R²) of 0.987. The calculated thermodynamic parameters showed that the biosorption of uranium ions was endothermic (ΔH° < 0). The results of scanning electron microscope and Fourier transform infrared spectrometry analysis revealed that nano-particles of uranium precipitation were formed on the cell surfaces after biosorption, and the functional groups of –CH, N-H, –COOH, P = O and the carbohydrates and alcohols were involved in the biosorption process between A. niger and uranium ions.