Study On Treating Low Concentration Acetic Acid Solution With Polypropylene HoIlow Fiber Membrane Extraction

Membrane extraction is a new separation technique combining membrane separation with liquid-liquid extraction. Compared with traditional liquid-liquid extraction process,it has some special advantages, such as no dispersion and coalescence of the two phase,lower solvent entrainment loss and higher extraction rate and so on. So the application study of membrane extraction has very important significance.During the production of furfural, it produce a lot of acetic acid wastewater which can bring about a serious pollution to the environment. In order to solve environmental pollution problems, we try to treat acetic acid wastewater with membrane extraction. In this paper, complexing agent was used as reacting agent with diluent and modifier. Respectively.particular experiments and analysis had been given for extraction characteristics and efficiency using hydrophobic polypropylene hollow fiber membrane modules. The effect of two phases velocity, initial acetic acid concentration, residence time of the water phase, HFM in series on extraction characteristics and efficiency has been analyzed.In the end, the author gives a brief analysis of mass transfer mechanism of membrane extraction.Acetic acid from wastewater was treated with hydrophobic polypropylene hollow fiber membrane. With increasing the two phases velocity, extraction rate is gradually decreased while mass transfer coefficient increasing for the membrane module A made with Membrana'siPP HFM.Membrane module B is made with iPP HFM prapared via thermally induced phase separation(TIPS).Compared with membrane module A, mass transfer coefficient of membrane module B is about half of module A's and the two phases velocity has no effect on mass transfer performance which shows that membrane resistance is major in the total mass transfer resistance. With increasing the initial concentration, the extraction rate and mass transfer efficiency gradually decreased. Extraction efficiency of the single-stage membrane module with specific surface area of 61.9m~2/m~3 can reach 60.5%. With the improvement of module stages, the trand of extraction rate is l inear increase. Hight of mass transfer unit of membrane module is between 0.1m and 0.6m which is lower than extraction tower's HTU.So membrane extraction treating with low concentration acetate solution is high efficiency and energy saving.On the base of studing all kind of factor affecting mass transfer in membrane extraction process, wo obtained the theoretical mass transfer coefficient which consistented to the experimental data and the daviation was about 14%.The results of this research will provide theoretical foundation for the design and industrialization of acetic acid wastewater treatment.