No abstract

The extraction of tungsten (VI) from hydrochloric acid solutions by trioctyl phosphine oxide (TOPO) and dihexyl sulphoxide (DHSO, R 2 SO) in benzene was investigated under various conditions. The organic extracts were examined by infrared spectrophotometry. As the results, the following equilibrium equations are proposed for the extraction by TOPO and DHSO: for TOPO, WO 2 Cl 2 (aq) + 2TOPO(org) WO 2 Cl 2 ・2TOPO (org) ; for DHSO, WO 2 Cl 2 (aq) + 2DHSO (org) WO 2 Cl 2 ・2DHSO (org). Here, it is shown that the extracted tungstic chloro complexes WO 2 Cl 2 ・2L (L = TOPO and DHSO) consist of the octahedral structure wherein tungsten (VI) has a coordination number of six. Further the extraction efficiencies for tungsten (VI) by TOPO and DHSO are compared with that by tributyl phosphate (TBP), and it emerges that their order is in TOPO > DHSO > TBP.