The Preparation And Properties Of Novel Pervaporation Membrane Materials And Their Application In Water Treatment

Because of the rapid development of economy and the increasing environmental pollution, China is experiencing one of its most severe water shortages, and this is a major challenge for many countries. Water shortages are most severe in the north of the country, where surface water diversion is excessive and groundwater is being depleted. In addition, the quality of water is deteriorating because of pollution, thereby aggravating existing water shortages. The traditional separation technology due to its own characteristics, in the process of removing the field of inorganic and organic matter has a certain limit. This article research the structure of membrane material and membrane preparation new pervaporation separation membrane, so as to achieve the performance of separation results. This paper reviews the research and development process of membrane material and membrane structure, successful preparation of a series of high separation performance of pervaporation composite membrane. At the same time, this paper carefully analyses the material of the membrane and the structure of the membrane for pervaporation separation technology and the relationship between the two, and further study of the pervaporation separation of theory and model of the pervaporation. The main jobs are shown bellow:1. The (PDMS-TiO2)/PVDF composite membrane was prepared with simple coating methods. The results showed that the membrane could selectively permeate formaldehyde over water and the best separation performance could be achieved at 50 ? with a separation factor of 13.1,and a total flux of 140.3 g·m-2·h-1. To the preparation of composite membrane under the condition of the temperature of 50 ?, operation for 25 hours straight, the composite membrane has the stable flux and rejection, it can prove that under the condition of high temperature for a long time operation, the composite membrane has a good stable performance.2. The SPTA-PVA/PVDF composite membrane was prepared with simple coating methods. Can be concluded from the results, the diffusion of water molecules have high ability, in the cortex of containing sulfonic acid groups. At 70 ?, 35000 ppm NaCl aqueous solution, and the highest water flux can be 35.7 L·m-2·h-1, and the basic rejection can remain above 99.8%. To the preparation of composite membrane under the condition of the temperature of 70 ?, operation for 25 hours straight, the composite membrane has the stable flux and rejection, it can prove that under the condition of high temperature for a long time operation, the composite membrane has a good stable performance.3. In this paper, the transfer mechanism of the composite membrane was studied, and the position of vaporization in the process of pervaporation was discovered. After SPTA-PVA/PVDF composite membrane pervaporation process 35000 ppm of NaCl aqueous solution,the EDS testing shows that the Na and Cl element content in PVA and PVDF border has obvious changes, Na element and Cl element cannot be boiled, and the pervaporation position was in PVA and PVDF border.4. Based on pervaporation composite membrane resistance calculation,we can know the resistance of dense layer with the reduce of dense layer thickness is reduced, the surface porosity of the support layer is smaller,the greater the average pore size, support layer resistance is smaller, thus to improve the mass transfer efficiency of composite membrane.