Study On The Fabrication Of Pervaporation Desalination Membranes With Excellent Oxidation Resistance

With the rapid development of society and increase of global population,the shortage of drinking water has become a worldwide problem,and the desalination technology becomes the key to solve this problem.The development of traditional desalination technology is limited due to its low efficiency and high energy consumption.Pervaporation(PV),as a new desalination technology,combines the advantages of thermal desalination and membrane desalination,and becomes one of the most potential technologies to solve the current water shortage.The key of PV technology is PV membrane,whose hydrophilicity makes it has good anti-fouling.But PV membrane is still inevitably fouled resulting in desalination performance decline.In the practical application process of PV membrane,the foulants are mainly organic matters,and the cleaning effect of sodium hypochlorite is excellent.Thus,the study of PV membrane with excellent chlorine-resistant cleaning is very important.Through the membrane material modification and structure design,we fabricate PV membrane with high flux and great oxidation resistance.The specific research content is as follows:1.The oxidation resistance of PVA was improved by removing the active 1,2(head-head)structures in PVA.Due to the good chemical resistance of the fluorocarbon chain,the crosslinking agent containing fluorocarbon chain was selected to cross link with PVA.The PVA-FS/PVDF composite membrane with a flux of 34.3±1.3 kg/m2·h and a salt rejection of 99.93%was prepared by spraying process.The oxidation resistance of PVA-FS/PVDF composite membrane was evaluated,and the results showed that the salt rejection remained unchanged,indicating that the oxidation resistance of PVA-FS/PVDF membrane was excellent.2.Further graft treatment of PVA reduced its crystallinity,which not only improved its hydrophilicity,but also facilitated the diffusion of small molecular crosslinkers.At the same time,two kinds of long chain crosslinking agents were added for comparison.The water flux of the SMA-g-PVA-FS/PVDF composite membrane was 44.5±1.5 kg/m2·h,and the salt rejection was 99.95%.At the same time,the oxidation resistance of the membrane was also improved,and the oxidation resistance reached 768000 ppm·h,which was higher than the RO and PV membrane reported at present.