Pure and Sb-doped ZrO2 for removal of IO3− from radioactive waste solutions

Radioactive 129I with a long half-life (1.57 × 107 y) and high mobility is a serious radiohazard and one of the top risk radionuclides associated with its accidental and planned releases to nature. The complex speciation chemistry of iodine makes its removal a complicated task, and usually a single method is not able to remove all iodine species. Especially its oxidized form iodate (IO3−) lacks a selective and effective removal method. Here, the granular aggregates of hydrous zirconium oxides with and without antimony doping were tested for IO3− removal and the effects of contact time, competing anions in different concentrations and pH were examined. The materials showed high selectivity for IO3− (Kd over up to 50,000 ml/g) in the presence of competing ions and relatively fast uptake kinetics (eq. < 1 h). However, B(OH)4− and SO42−, as competing ions, lowered the iodate uptake significantly in basic and acidic solution, respectively. The suitability of the materials for practical applications was tested in a series of column experiments where the materials showed remarkably high apparent capacity for the IO3− uptake (3.2–3.5 mmol/g). Graphic abstract

Selective Sorption of Ge(IV) Oxoanion by Composite Sorbent Based on Hydrous Oxide of Zirconium

In this work, a composite sorbent based on hydrous zirconium oxide was used for selective removal of Ge(IV) oxoanions. Experiments were carried out by batch equilibrium tests and dynamic column sorption. The best sorption capacity was reached at the pH of 9, when about 4.3 g of Ge by liter of composite. The negative effect of the concentration of chlorides and sulfates was observed when their concentration was higher than 500 mg/L. The optimal specific solution flow rate for sorption by ZrO2-PAN sorbent was determined to be 6 BV/h. For regeneration, 15 BV of 0.5 M HCl solution saturated with NaCl was used.