Membranes Preparation And Structure Of Control

Polyethersulfone is one of the widely used membrane materials due to its excellent property .Its glass transformation temperature is as high as 225℃,and it has excellent thermal properties,compression resistance, corrosion resistance,chemical stability and biocompatibility. For membrane preparation, the solution phase inversion method has the advantage of the simple technical conditions. But during the process of membrane preparation, the control of membrane structures is difficult, and membrane reproducibility is poor and membrane mechanical strength is inferior. In this paper, we aimed at studying the influences of various technical conditions on phase separation behaviors and membrane structures during PES membrane formation by the solution phase inversion method. The PES membrane formation rules was suggested. The relations of technical conditions, phase separation behaviors and membrane structures were obtained. So the membrane structures can be controlled during preparation process. On the basis of membrane formation rules of membrane preparation mentioned above, the flat homogeneous PES microporous membrane with good performances and controllable structures were prepared. And the performances of these membranes were investigated.Based on the above studies, the homogeneous microporous PES membranes were prepared by two-step gelation with porous top surface, high porosity, good mechanical strength, high water flux and uniform structure. The pore diameter on the top layer and porosity were 1—10 μm and approximate 70%, respectively. The max stress and its break stress of membranes was higher than that of membrane without nano-TiO2. The range of the water flux was 986~ 15783 L/h.m2,. Finally, The preparation conditions of membrane with excellent performance were summarized as follows: PES concentrations varied from 11wt% to 15wt%, the content of PVP was 3-5 wt%, the content range of water additive was 1-5 wt%, the content of nano-TiO2 was from 0.2wt% to lwt%, coagulation baths consisted of water and DMAc and the volume content of DMAc was 30-80%, the temperatures of casting solutions and coagulation baths were about 30℃, respectively.By pilotscale experiment, the homogeneous mricroporous PES membranes were successfully prepared by two-step gelation with a porous top surface,high porosity, good mechanical strength, and high water flux and uniform structure.