A clean and efficient method for separation of vanadium and molybdenum by aqueous two-phase systems

Abstract The growing demand for vanadium and molybdenum in the high-tech industry has spurred researches into recycling from a variety of sources. A green and simple process for separation of vanadium and molybdenum was proposed by aqueous two-phase systems consisting of non-ionic surfactants (triblock copolymer, L35; octaphenyl polyoxyethylene, Triton X-100 and polyethylene glycol, PEG2000) and sodium sulfate without any extractant. The effects of aqueous pH, temperature, vanadium and molybdenum concentration，and different surfactants on separation performance of vanadium and molybdenum were systematically studied. The results indicated that the extraction rate of molybdenum and vanadium increased from 73% to 92% and from 11% to 30%, respectively, with increasing aqueous pH from 0.6 to 0.9. The extraction rate of vanadium decreased and the extraction rate of molybdenum increased with increasing temperature from 313.15 K to 343.15 K. Furthermore, with strengthening of molybdenum concentration from 1 g/L to 10 g/L and vanadium concentration from 1 g/L to 5 g/L, the extraction rate of vanadium and molybdenum increased. The sequence on separation efficiency of both metals is L35, Triton X-100 and PEG2000 from high to low. The extraction rate of molybdenum reached 91% and the extraction rate of vanadium was below 18% and the separation factor of both metals was above 47 under the optimal conditions of aqueous pH of 0.70–0.75 and extracting temperature of 343.15 K for L35 + Na2SO4 + H2O aqueous two-phase system. It has obvious advantages in terms of safety production, environmental protection compared with traditional organic solvent extraction method.