Preparation Of PVA Nanofiltration Membranes Using Supercritical CO₂ As A Pore Opener

The technique of separating by membranes is a new effective, forehanded method, which have been widely used and developed. But the traditional method always introduces troubles in preparation. Such as solvent remaining, low rate of pore, et al. To solve these problems, we did some research in preparing membranes using supercritical CO₂ (SC-CO₂) fluid as a pore opener, and discussed the application in separating erythromycin.Using PVA as main materials, glutaraldehyde as a cross-link agent, to prepare PVA nanofiltration(NF) membranes through two kinds of process: (1) Using SC-CO₂ as a non-solvent to induce the phase separating in polymer solution; (2) Using SC-CO₂ as a foamer make pores in the dry polymer. The role played by PVA concentration, cross-linking conditions in the formation of NF membranes is investigated. The structure and separation performance of the NF membranes are researched systematically. Water flux, erythromycin retention and flux are investigated by Qudric Dynamic Instrument. Mesh size is measured by rentention of PEG that has different molecular weights. Microstructure of NF membranes is characterized by FT-IR, DSC, SEM and X ray diffraction. And the heat resistance, acid-base resistance, solvent resistance, swelling and mechanical properties of the NF membranes are investigated. Then the effect on filtration and purification of the erythromycin in different operation conditions is discussed.The result showed that the NF membranes which prepared using SC-CO₂ have a outstanding properties. The ternary cycle erythromycin retention and flux of NF membranes are 93.4% and 44.3 L·h^-1·m^-2 respectively. As a conclusion, the NF membranes have a prospected application in extracting erythromycin.By doing the research, the problems in preparing by traditional method have been solved effectively. And also, the properties of PVA membranes have been improved through plasticized by SC-CO₂.