Separation And Extraction Of Heavy Metal Ions By Emulsion Liquid Membrane Technique

As a newly-developed method for membrane separation, the technology of liquid membrane separation presents high efficiency, selectivity, ratio of enrichment and short process and low cost as it comprehends the advantage of the methods both solid membrane separation and solvent extraction. The technique displays broad application in many fields such as treatment of wastewater, biological medicine and chemical separation. In this paper, based on the work of predecessors, the separation and extraction of heavy metal ions by emulsion liquid membrane technique was studied.The thesis is divided into four parts. In chapter one, the separation method of metal ions is summarized. The theory and application of the methods is described.In chapter two, the transfer behavior of silver ion through emulsion liquid membrane system was studied. Kerosene was used the membrane solvent, span80 (sorbitan monooleate) as the surfactant, TBP (tributylphosphate) as the carrier, paraffin as the membrane reinforce, NH3 as the reagents in internal phase, The effect of stirring velocity on emulsifying, emulsifying time and mixing time of emulsion and water, the concentration of span80, TBP and paraffin, the concentration of NH3 in internal phase have been discussed in detail and the optimum conditions were established.In chapter three, the separation and extraction of zinc ion using the liquid membrane system of span80-TBP-NH3 was investigated. TBP as a carrier entered through membrane phase after the neutral complex was formed with zinc ion on the interface between membrane and external phase and then returned to membrane phase after it was released from the complex as a result of the formation of [Zn(NH3)]2+ by the reaction of the neutral complex with NH3 on interface between membrane and internal phase. The separation of zinc ion from external phase could be obtained by using NH3 in internal phase to facilitate zinc ion to transfer in the solution. Under the optimum conditions, the percentage of the extraction of zinc ion was over 80%. The separation of zinc ion from coexisted metal ion as well as the reusage of oil phase were tested.In chapter four, the separation and extraction of copper ion by using the system of span80-APS(p-amino-phenylsulfonic acid)-NH3 was studied. The optimum conditions were established. The stirring speed for emulsification was 3500r/min, the emulsifying time and mixing time of milk and external phase solution were 10min and 20min respectively. The ratio of milk to water and oil phase to internal phase were 0.38 and 0.44 respectively. The concentration of APS, span80 and paraffin were 11%, 4.4% and 2.2% respectively. The concentration of NH3 in internal phase and HCl in external phase were 4mol/L and 0.5mol/L respectively. The copper ion in the imitated sample was separated and extracted by using the system.