Studies On Supported Liquid Membrane Separation Of Heavy Metal Ions In Water Environment

The liquid membrane separation technology have the character as with single equipment, rapid separation rate, fine separation select quality, low energy consume and is a new separation technology studied in recent years. And the supported liquid membrane technology have been recommended as a new technology to separate, concentrate and receive metal ions.The effects of pH values in feed solution, carrier concentrations, temperature and concentrations in feed solution on the transport rate of heavy metal ions containing Cd(II) ?Zn(II), Co(II) and Ni(II) through a supported liquid membrane consisting of a 2-ethylhexylphosphonic acid mono- 2-ethylhexyl ester (PC-88A) solution in CHCh, adsorbed on a polypropylene microporous film, were studied. And the best conditions to transfer these ions are listed as below:Metal ionspH values in feed solutionPC-88A/ (mol/L)Temperature/KCd(II)5.0-5.40.12-0.17280-298Zn(II)4.6-5.40.12-0.19293-308Co(II)5.4-6.00.10-0.19280-298Ni(II)5.7-6.00.12-0.17280-298The second part of the paper is about the separations of Cd(II) and Zn(II)> Co(II) and Ni(II) > and Cd(II) ^ Zn(II^ Co(II) and Ni(II) by the control of the acidity of feed solution. And in the second part, a new supported liquid membrane system consisting of PC-88A as main carrier and tributyl phosphate(TBP) as synergistic carrier, CHC^ as membrane solvent, adsorbed on the polypropylene microporous film, fySC^ as stripping phase was studied to separate Zn(II) and Cd(II). The optimum conditions obtained are listed as below:Metal ionsPC-88ATBPpH values in feed solutionstripping solutiontimeZn(II)Cd(II)0.12mol/L0.035mol/L3.0-3.40.33mol/LH2SO430~40minCo(II)Ni(II)0.17mol/L-----5.0l.Omol/LHCl90minThe optimum conditions to separate the mixture of Cd(II) , Zn(II^ Co(II) and Ni(II) are listed as below:Metal ionspH values in feed solutionstripping solutionTemperature /KZn(II)/Cd(II)Co(II)Ni(II)3.6l.Omol/LHCl298Cd(II)/Co(II)Ni(II)4.60. 33mol/LH2SO4298Co(II)/Ni(II)5.0l.Omol/LHCl308The third part of the paper is the transport analysis of supported liquid membrane system. The permeability coefficient, aqueous diffusion film thickness, and diffusion coefficient of Cd(Il) ion through the supported liquid membrane have been measured though the experimental results. The data were explained by a previously derived equation in terms of membrane diffusion, aqueous film diffusion, and aqueous complex formation chemistry.