| In this paper,the whole system is divided into three phases by using hollow fiber liquid membrane technique,which are the feed phase,the membrane phase and the stripping phase,to explore the effective method of extracting SPM.Firstly,the complex extraction experiment is composed of TOMAC and Butyl acetate,the main factors that affecting the extraction process and re-extraction process were studied.We also interconnected the extraction process and the re-extraction process to test the feasibility of liquid membrane technique.The result showed that at 25?,the time of extraction process was 9h,the best pH of the feed phase for the extraction was 10,and the best pH of the stripping phase was 3.8,the optimal concentration of TOMAC in the mixed extraction solvent was 0.06 mol/L.The extraction rate could reach 89%.Secondly,we used the hollow fiber membrane model to improve the separation efficiency of the liquid membrane.The result showed that compared with other materials,pp membrane model had the advantage of corrosion resistance,moderate microporous and the low price,which was fit for this subject.We got that the operating time of the process was 5h,the suitable transmembrane pressure was 0.03 MPa,the best tube side flow rate was 150 ml/min,the best shell side flow rate was 120 ml/min,the volume ratio of the pre-dispersing mixed extractant was 1:9,the extraction rate could reach 91%.Moreover,the stability of the liquid membrane was studied through five times continuous experiments,which showed a good stability.Mass transfer resistances were analyzed by building the mathematical model,showing the resistance from the extraction reaction to be dominant.At last,in this paper,we used the growing drop method to research the effect of the mixed extractant on the extraction kinetics.By fitting the data,we got the extraction rate equation,the extraction rate constant and the corresponding series,which laid the foundation for further optimization of extraction rate. |
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