Preparation Of Zeolite NaA Membrane On Polysulfone Hollow Fiber Supports

As a new membrane separation technology, pervaporation has been widely studied and applied. Compared with other forms of membrane module, hollow fiber membrane module has advantages of high loading density, small area of device, self supported components saving cost etc. At present polymer materials is the most attention material of the hollow fiber pervaporation membrane materials. But polymer material has some questions on swelling, poo thermal stability, low permeation flux and small separation factor. The common inorganic materials, such as zeolite NaA, was prepared in the high-cost supports, and also has some problem about having larger size of the membrane module and low filling rate.Therefore, synthesis of zeolite NaA membranes on the organic hollow fiber has a certain practical significance to solve the above problems. However, with the difference between the support and the zeolite NaA, zeolite NaA was easy to fall off from the support. The combination between organic hollow fiber membrane and zeolite NaA has become a new challenge.In this work, Zeolite NaA membranes were prepared on the outer Surface of hollow fiber supports coating the intermediate layer. The dense and continuous Zeolite NaA membrane on the organic hollow fiber support was attained.First of all, Zeolite NaA membranes were successfully prepared on the outer Surface of hollow fiber supports by adding hydrophilic PVA intermediate layer. The influence of adding the intermediate layer, the synthesis time, seeds size, the number of coating membrane on the forming and performance of zeolite NaA membranes are diseussed. And the film process is optimized. The results show that coating PVA is benefit for synthesis of NaA membrane without obvious defects on PSf hollow fiber support. The best condition of preparation the membrane is 6 h synthesis time,90 nm seed size,3 times seeds coating. The separation factor of zeolite NaA membrane is 37.28, and the flux is 3.53 kg·m-2·h-1.To further optimize the preparation process of the membrane, the polymer/NaA composite layer is coated on the surface of hollow fiber. Then Zeolite NaA membranes were prepared on the outer surface of this hollow fiber supports. This method can omit the coating seeds steps. The influence of materials of the intermediate layer, the synthesis time, coating method, content of seeds on the forming and performance of zeolite NaA membranes are diseussed. The results show that the separation performance of the zeolite NaA membrane with ethyl cellulose ethoce (EC)/NaA composite layer is higher than the separation performance of the zeolite NaA membrane with PVA coating. Coating method has great influence on separation performance of zeolite NaA membrane. The composite intermediate layer, which prepared by dip-coating in the membrane solution of 4wt%EC-50wt% first and the membrane solution of 1.5wt%EC-xwt%NaA (xwt% is the content of NaA) second time, was beneficial for the synthesis of zeolite NaA membrane. The optimal content of NaA is 80wt%, and the optimum time is greater than 6 h. With intermediate seeds layer, the separation factor of the zeolite NaA membrane prepared on the PSf support was 62.19 and the flux was 2.07 ke·m-2 h-1.