Praparation Of A New ELM System And Its Non-Dispersive Extraction For Gallium And Indium

The main problems of traditional emulsification liquid membrane were good stability but bad demulsify and easy occurring secondary emulsification and swelling when dispersive extraction .So the aim of this research is preparing a kind of emulsion with good stability at normal temperature and easy demulsify through heated method. And using this emulsion with a hollow-fiber supported emulsification liquid membrane for extraction of gallium and indium and its mass transfer properties had been carried out in this paper. The major works and conclusions are described as followings:(1) The W/O emulsion system is consisted of BF-100[polyoxyethylene(4) -nonylphenol], D₂EHPA[di(2-ethylhexyl)phosphoric acid], paraffin oil, kerosene as well as HCl solution, in which BF-100 is nonionic surfactants, D₂EHPA is mobile carrier in the liquid membrane system, paraffin oil is membrane intensifier, kerosene is the diluter, and HCl solution acted as striping agent in the receiving phase of emulsion. The effects of the emulsifier concentration, the R_oi(the oil/H₂O volume ratio of emulsion), the saponification degree of D₂EHPA, the concentration of HCl solution, the stirring time and the temperature on the stability of emulsion system were studied. The emulsion was characterized by conductivity meter, viscosimeter, particle size analyzer, biological microscope. The results showed that the good stability emulsion can be made when the emulsifier concentration was in 3% - 6%(wt), the R_oi was 4:6 - 6:4, saponification degree of D₂EHPA was 30%-80%, HCl concentration was 1-5mol·L^-1, string time was 15-30min. When the emulsion was placed in a thermostated water bath maintained at a constant temperature of 60℃for 10min, the demulsificated percentage reached 100%. Under comparable conditions, the other three emulsions prepared by Span80, ENJ-3029, Lan-113A respectively could not be demulsificated any.(2) The results of extracting gallium and indium by hollow-fiber supported emulsification liquid membrane were obtained as follows: The lower flow rate of emulsions, the higher extraction percentage and enrichment-fold under the same flow rate of emulsions and feed aqueous; Along with the saponification degree of D₂EHPA ,the extraction was reduced, but the enrichment-fold was increased; The extraction percentage of Ga³⁺,In³⁺ reached the max when the BF-100 mass ratio respectively account to 4%, 3%; The extraction percentage was declined with the rising of HC1 concentration and R_oi, but the enrichment-fold was augmented, the optimal HC1 concentration was 3 -5mol·L^-1,and the R_oi was 4:6-7:3,and we also found that the extraction percentage was declining with the rising of initial feed aqueous concentrations; As the emulsion was recycled with 30 times by this equipment, the Ga³⁺ In³⁺ concentration in receiving phase was respectively reached to 26.1 and 24.9, but it only 5.11 and 6.37 by dispersive extraction; Ga³⁺,Al³⁺,Zn²⁺ were separated by this technique and the extraction percentage of Ga³⁺ was 79.6%, the separation coefficient wasβ_Ga/Al=3.4,β_Ga/Zn=4.2 . In³⁺,Fe³⁺,Zn²⁺,Cu²⁺ can also separated and the extraction percentage of In³⁺ was 80.4% , the separation coefficient wasβ_In/Fe=1.65,β_In/Zn=6.55,β_In/Cu=6.32. (3) The main conclusions of study on the mass transfer properties were obtained as follows: The permeate flux and permeability coefficient of Ga³⁺,In³⁺ were increased with the increasing of flow rate of feed aqueous solution; The total mass transfer coefficients K_w,exp were declined with the rising of HC1 and feed aqueous solution concentrations; Relationships between the water phase mass transfer coefficients K_w and flow rate of water phase u_w^1/3 were linearity; The K_w was increased with the augmenting of flow rate of feed aqueous solution...