Removal of cobalt from radioactive liquid waste by oxine impregnated activated charcoal

Fundamental experiments on radio-cobalt ion removal characteristics of oxine impregnated activated charcoal in sodium sulfate solution were performed, in order to evaluate the applicability of this adsorbent to treat radioactive liquid waste which contained a large amount of salts. The effects of sodium sulfate concentration, pH, cobalt ion concentration, type of carrier activated charcoal and coexistence ion (CO₃^2-, Ca²⁺, Mg²⁺, Ni²⁺, Zn²⁺) were studied. Column experiments showed that cobalt ions could be removed selectively under the conditions of Na₂SO₄ concentration 0 ∼ 20 w/o and pH 7.5 ∼ 10. However removal efficiency decreased as the acidity of the solution increased. As to the effect of coexistence ion, slightly decrease in the efficiency was observed under the presence of CO₃^2-, Ca²⁺ and Mg²⁺ ions. However removal efficiency decreased as the presence of transition divalent metal ions, such as Ni²⁺ and Zn²⁺ ions. Cobalt removal efficiency is not influenced under the type of carrier activated charcoal. And cobalt ions could be removed selectively too in the Na₂B₄O₇ solution. (author)