聚氨酯膜分离丙酮／正丁醇溶液的渗透汽化性能研究

Study on Polyurethane Membranes for Separation Acetone/n-butanol Mixture by Pervaporation

本文研究聚氨酯（PU）膜分离丙酮／正丁醇体系的渗透汽化性能。通过溶胀实验发现，PU膜表现出良好的优先透丙酮性能。随后进一步研究实验条件变化对聚氨酯膜的渗透汽化性能的影响。通过考察料液中丙酮浓度，操作温度对PU膜渗透汽化性能的影响发现：随着温度的升高，渗透通量变大，而分离因子下降。渗透通量随温度的增加是由于温度的增加使膜材料分子链段的运动加剧，自由体积增加，渗透物动能随之增加，液体在膜中溶胀度扣分子在膜中的扩散速度都相应升高，渗透通量就增大了；而分离因子的下降也可以通过Arrhenius公式中丙酮扣正丁醇的活化能大小很好地解释。随着料液中丙酮浓度的增加，渗透通量也随之增加，当丙酮含量达到20wt％时，渗透通量达到最大值750g／m^2h；反之分离因子却随浓度的增加而减小，当浓度从6wt％到20wt％，分离因子从10下降到3.8。

In this paper, Polyurethane （PU）membranes are potentially selective for separation of organic compounds from a mixture by pervaporation. The swelling experiment shows PU membrane exhibits high selectivity and permeability towards acetone, and then the pervaporation performances of the membrane have been studied. With an increase of the feed tempera-ture, selectivity decreases, the phenomenon can be explained that activation energy of n-butanol is larger than that of acetone, and the permeation flux increases with the increasing temperature, it can be due to the fact that permeating molecules diffuse through free volumes of the membrane. Thermal motions of polymer chains in amorphous regions randomly produce free volumes. With the enhancement of the concentration of acetone in the mixture from 6 wt% to 20 wt%, flux gets a rise, and it reaches the maximum value, 750g/m^2h; but the selectivity decreases from 10 to 3.8 ,it can be due to the swelling effect of the membrane in the mixture.