Extraction of Ni by microemulsion

The microemulsion system of oleic acid/butanol/sodium carbonate solution was used to extract metal ion Ni~(2+).The main experimental parameters,which influence extraction rate,such as the constitution of microemulsion,pH value in aqueous phase,R_(ew),stirring time,were studied.The experimental results show the extraction rate of Ni~(2+) can reach 99.91%,and the concentration of Ni~(2+) can be reduced to 0.7 mg/L from its initial concentration of 500 mg/L under the condition of oleic acid/butanol/sodium carbonate solution=5∶5∶4(volume ratio),R_(io)=2.5,R_(ew)=1∶7, stirring time 6 min,pH values 5.1～5.8.The microemulsion system did not swell in the process of extraction when the concentration of NaCl in the aqueous phase is higher than 1.5 g/L.The oil phase can be recycled by changing the pH value to demulsify the microemulsion system and the recycling experiment demonstrates that the oil phase can be reused for five times with little change of extraction rate.