A Study On Separation Technique Of Metal Ions By Liquid Membrane In Water Environment

A inner coupled liquid membrane containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A) as a mobile carrier was used to study the transport rule of four metal ions which were Zn(II),Cd(II),Co(II) and Ni(n), by investigating the effects of variation in such factors as pH values in feed phase, temperature, the concentrations of carrier in the liquid membrane and concentration of hydrogen ions in stripping solution on the transport rate. This paper is consisted of three parts: the transport of metal ions in liquid membrane system, analyzing transfer kinetics of metal ions and obtaining a mathematical modes for the transport of metal ions.An increase in temperature ,concentrations of carrier and pH values in stripping phase caused an increase in the transport rate of each metal ions, but an increase in ion intension in feed phase decreased it The stripping rate of each metal ions in stripping was influenced by more factor. It was higher with a higher transfer rate of metal ions in feed phase and concentrations of hydrogen ion hi stripping solution. The emulsifying hi membrane phase could cause an decrease hi the stripping rate and the ultimate amount of metal ions retarded in the membrane phase, which was more vulnerable to emulsified at an higher pH values. For the Liquid transports of Cd(II), Co(II) and Zn(II), the best transport conditions were defined to be pH values hi feed solution 4.5-5.1, 4.6-5.2 and 2.6-5.0, respectively. The carrier concentration was defined to be 5.0%-7.5% and the temperature was defined to be 298K-303K for each metal ion.The liquid membrane separations of Zn(n)-Cd(II), Cd(D>Ni(II), Co(II)- Ni(H) and Zn(n)-Cu(n) mixture solutions of were separated by controlling pH values in feed phase, respectively. The transfer kinetics of metal ions in this system was also studied by using interfacial chemistry theory and transfer kinetics, and a mathematical model was obtained for a inner coupled liquid membrane system. This model was verified to be consistent well with the experimental results.