Study on transport of Dy(Ⅲ) by dispersion supported liquid membrane

The transport of Dy(Ⅲ) through a dispersion supported liquid membrane(DSLM) consisting of polyvinylidene fluoride membrane(PVDF) as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester(PC-88A) dissolved in kerosene as the membrane solution,was studied. The effects of pH value,initial concentration of Dy(Ⅲ) and different ionic strength in the feed phase,volume ratio of membrane solution and stripping solution,concentration of HCl solution,concentration of carrier,different stripping agents in the dispersion phase on transport of Dy(Ⅲ) were also investigated,respectively. As a result,when the concentration of HCl solution was 4.0 mol/L,concentration of PC-88A was 0.10 mol/L,and volume ratio of membrane solution and stripping solution was 40:20 in the dispersion phase,and pH value was 5.0 in the feed phase,the transport effect of Dy(Ⅲ) was the best. Ionic strength had no obvious effect on transport of Dy(Ⅲ) . Under the optimum condition studied,when initial concentration of Dy(Ⅲ) was 0.8×10-4 mol/L,the transport rate of Dy(Ⅲ) was up to 96.2% during the transport time of 95 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The diffusion coefficient of Dy(Ⅲ) in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.99×10-7 m2/s and 15.97 μm,respectively. The results were in good agreement with experimental results.