Selective sorption of thorium (IV) from highly acidic aqueous solutions by rice and wheat bran

In this research, various biomaterials were evaluated for selective sorption of Th(IV) ion from highly acidic aqueous solutions. According to the high sorption efficiency of rice bran (RB) and wheat bran (WB) in the strong acidic media, these sorbents were selected among the proposed biomaterials for the research. The sorption capacities obtained from distribution isotherms in 4 M HNO3 indicated values of 49.3 and 38.7 mg g(-1) for RB and WB respectively. Also, the sorption equilibriums were achieved in less than 2 and 10 min for RB and WB respectively. Sorption efficiencies using 1 g bran in the concentration range of 200-3,000 mg L-1 were relatively constant (> 90 % and > 71 for RB and WB respectively) with R.S.D. less than 2 %. In a single batch step, extraction of thorium from a real sample (monazite mineral) was studied and extraction efficiencies of 95.4 and 74.6 % were achieved from 4 M nitric acid for RB and WB respectively. The selected biosorbents have the potential to be applied on industrial scale because of economic and operational benefits.