Photoreductive Stripping of Cobalt Loaded on Hydroxyoxime Extractant in a Liquid−Liquid Extraction System

The photoreductive stripping of cobalt from hydroxyoxime extractants was investigated, employing 2-hydroxy-5-nonylacetophenone oxime (LIX-84I) and 2-hydroxy-5-nonylbenzophenone oxime (LIX-65N) as extractants, n-dodecane as the diluent, and a halogen lamp as the light source. The stripping of cobalt is barely achieved by conventional stripping, in this extraction system, because of the oxidation of the cobalt-hydroxyoxime complex by electron attraction with the O 2 molecule. The stripping of cobalt is, however, substantially improved by photoirradiation using light of visible radiation wavelength. The organic solution obtained following photoirradiation can be reused for repeated extraction and photoreductive stripping processing.