Treatment of tissue paper containing radioactive waste and electrochemical recovery of valuables using ionic liquids

摘要

Dissolution of tissue paper waste containing valuable contaminants such as uranium and palladium in l-butyl-3-methylimidazolium chloride (bmimCl) has been studied. Dissolution of 5-7 wt.% tissue paper in bmimCl is complete within 60 min at 373 K and the time required for dissolution increases with increase of loading. It is difficult to dissolve more than 10 wt.% tissue paper in bmimCl and the limiting solubility of tissue paper is 15-17 wt.% at 373 K. Uranium(VI) and Pd(II) in chlorideitrate form dissolve in bmimCl along with tissue paper. The electrochemical behaviour of uranium(VI) and palladium(II) in the resultant solution in the presence and absence of a co-solvent, DMSO, has been investigated by transient voltammetric techniques at glassy carbon working electrode and the diffusion coefficients have been determined. Electrolysis of a solution of uranium(VI) and palladium(II) loaded tissue paper in bmimCl results in deposition of uranium oxide (UO{sub}2) and metallic palladium, respectively, which were characterized by X-ray diffraction and scanning electron microscopy. The study established the possibility of dissolving tissue paper and other cellulose based materials containing soluble uranium(VI) and Pd(II) compounds in bmimCl, and their recovery from the resultant solution. Cellulose pulp can be regenerated by adding surplus water after the recovery of valuables and the ionic liquid, bmimCl, can be regenerated for further use by vacuum distillation of DMSO and water.