Fungal bio sorption of radionuclide in waste water after acid processing of monazite

Abstract

Removal and recovery of U(VI) and Th+4 from aqueous solution by both native and chemically modified biomass, by hydroxyl ammonium sulfate (HAS) + NaOH derived from Aspergillus nidulans was investigated by performing biosorption – desorption experiments. These biosorbents were selected after screening a range of fungal species. At the present work various adsorption parameters such as pH, initial metal concentration, biosorbent dose, biosorbent particles size, contact time and temperature were studied. Biosorbents were characterized by FTIR, XPS, Zeta potential, SEM and EDX. The optimum pH for U(VI) removal was 4.0 with U concentration 350 ppm, biomass concentration 0.4gm, biomass size 0.250 mm within 15 min at room temperature and the optimum pH for Th+4 removal was 2.0, biomass concentration 0.05gm with Th concentration 300ppm, biomass size 0.075 mm within 7 min at room temperature for native biomass and with Th+4 concentration 200ppm, biomass size 0.250 mm within 25 min at room temperature for chemically modified biomass. Uranium biosorption was found to closely follow the Langmuir isotherm model and thorium biosorption was found to closely follow the Freundlich isotherm model. Also, uranium and thorium biosorption obey pseudo second order kinetic model. Calculation suggested that U(VI) and Th+4 biosorption process was exothermic and endothermic, respectively. The amino, hydroxyl and carboxyl group on the fungal surface could contribute to U(VI) and Th+4 biosorption.