SYNERGISTIC SOLVENT-EXTRACTION STUDIES OF URANIUM(VI) USING A COMBINATION OF NAPHTHENIC ACID AND VARIOUS NEUTRAL DONORS INTO BENZENE

The equilibrium extraction behavior of uranium(VI) using a benzene sol ution containing naphthenic acid either alone or combined with one of the adductants viz., diphenyl sulphoxide, dinonyl sulphoxide, tri-n-bu tyl phosphate, triphenyl phosphine oxide, tri-n-octyl phosphine oxide, triphenyl arsine oxide, 2,9 dimethyl 1,10-phenanthroline, 1,10-phenan throline, 4,7-diphenyl 1,10-phenanthroline, 2,2'-bipyridyl and 2,2'-bi quinoline is described. The enhancement in the extraction by addition of such neutral adducts is explained in terms of adduct formation of t he metal chelates in the organic phase. The composition of the extract ed species is obtained from slope analysis and pH(0.5) values are also obtained. The effect of various parameters such as equilibrium pH, ex tractant concentration, various diluents on the extraction of U(VI) wi th 2% naphthenic acid has been carried our. Stripping or back extracti on with various mineral acids was also studied.