Recovery of uranium from solutions using Aspergillus nidulans isolated from monazite mineral

Aspergillus nidulans (accession number MT355567) was selected as a most potent isolated, dried and chemically pretreated biomass was investigated. Various biosorption parameters as pH, initial concentration of U, biosorbent dose, biosorbent particles size, temperature and contact time were studied. Maximum uranium removal efficiency was 97% and 98.5% for dried and chemically pretreated biomass, respectively. The optimum pH for U(VI) removal was 4.0 with U concentration 350 mg/L, biomass concentration 0.4 g, biomass size 0.250 mm within 16 and 14 min for dried and chemically pretreated biomass, respectively, at 25 degrees C. Uranium biosorption was closely related to pseudo-second-order kinetic model and obeys the Langmuir isotherm model. Calculation were suggested that U biosorption was not endothermic. According to the calculation the hydroxyl, carboxyl and amino groups on the fungal surface could back to biosorption of U. Desorption of U from the metal laden (68% for dried biomass and 47.5% for chemical-treated biomass) was completely achieved by applying 2 M HNO3 although the U adsorption capacity of both biosorbents were decreased from 67.5% to 28% for dried biomass and from 47.3% to 26% for chemical-treated biomass after four biosorption-desorption cycles.