预涂动态膜强化渗透与截留性能研究

Study on enhancing permeation and retention performance of precoating dynamic membrane

以二氧化钛粉体材料为涂膜剂,陶瓷管为基膜制备预涂动态膜,引入通量增强系数Zi和截留增强系数Fi研究了预涂动态膜制备条件对其强化渗透与截留性能的影响,并用SEM电镜对预涂动态膜和基膜表面形貌进行表征。结果表明:制备的预涂动态膜表面均匀密实,其孔径低于基膜平均孔径。预涂动态膜的渗透与截留性能随涂膜液pH值的增加而增加,在跨膜压差低于0.2 MPa、错流速度低于1.5 m/s,涂膜时间少于30 m in和涂膜液浓度低于0.4 g/L范围内,提高这些参数值有利于提高预涂动态膜的渗透与截留性能,超出此范围时,提高这些参数值对增强其渗透与截留性能的效果已不明显,其中错流速度的影响相对小些。跨膜压差为0.2 MPa,错流速度为1.5 m/s,涂膜时间30 m in,涂膜液浓度和pH值分别为0.4 g/L和10.2时为最佳制备条件。

The precoating dynamic membrane was prepared using the titanium dioxide powders and the ceramic tube as precoating material and substrate membrane,respectively.Through inducing the flux enhancement coefficient Zi and retention enhancement coefficient Fi,the influences of the preparing conditions of the dynamic membrane on its permeation and retention performance were investigated.The surface topography of the dynamic membrane and substrate membrane were characterized by the SEM.The results showed that the surface of the dynamic membrane was very uniform and smooth.The pore diameter of the dynamic membrane was lower than the average pore diameter of the substrate membrane.The permeation and retention performance increased with the rise of the pH of the coating solution.When the parameters such as the transmembrane pressure,the crossflow velocity,coating time and concentration of the coating solution were less than 0.2 MPa,1.5 m/s,30 min and 0.4 g/L,respectively,the rise of these parameters was favorable for improving the permeation and retention performance.But little effect of the crossflow velocity was observed.Beyond these ranges,the permeation and retention performance changed very little with the increasing of the parameter values.The optimal preparing conditions of the precoating dynamic membrane includes： the transmembrane pressure 0.2 MPa,the crossflow velocity 1.5 m/s,the coating time 30 min,the concentration of the coating solution 0.4 g/L and the pH value of the coating solution 10.2.