Performance Of Antifouling Polyethersulfone Ultrafiltration Membranes And Application In Refinement Of Traditional Chinese Medicine

Membrane separation, as an advanced technology for purification, has excellent prospects of application in modernization and production of Traditional Chinese Medicine. In this dissertation, we chose polyethersulfone polymer as membrane matrix and Pluronic F127 as additive, prepared a series of PES/Pluronic F127 antifouling ultrafiltration membrane and then used in Traditional Chinese Medicine refining process. Based on experimental investigation of model system, refinement of Rhizoma Coptidis, Radix Astragali and Flos Lonicerae Japonicae aqueous solutions were carried out in order to tentatively offer preliminary information and guidance on the modernization of Traditional Chinese Medicine using antifouling ultrafiltration membranes.The PES/Pluronic F127 antifouling membrane was well prepared and the separation performance and antifouling ability was studied. Scanning Electron Microscope (SEM), static water contact angle measurement, X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) were all introduced to characterize the antifouling membranes. The introduction of Pluronic F127 had greatly improved the hydrophilicity of membrane and pore surface. The flux recovery ratio reached as high as 94%, far beyond 62% of PES control membrane. The pure water flux enhanced with an increasing Pluronic F127 amount, while the rejection ratios of BSA remained higher than 97%. The dual role of Pluronic F127 as surface modifier and pore-forming agent was distinctly observed and tentatively analyzed. During the dissolution and subsequent coagulation process, some Pluronic F127 molecules are bound to and/or tangled with PES chains due to the presence of hydrophobic PPO blocks, and then spontaneously segregate to the membrane/water interfaces due to the presence of hydrophilic PEO blocks. Meanwhile, the majority of Pluronic F127 molecules self-assemble into spherical micelles with core/shell configuration. These micelles are extracted into the coagulation bath during the coagulation process and the spaces they once occupied will turn into the pores of the membranes.Among materials widely existed in Traditional Chinese Medicine solutions, we chose protein solution, tannin solutions, polysaccharide solution and their mixtures as model systems to investigate separation performance and antifouling ability during ultrafiltration. Research results revealed that although the interactions between membranes and various solutions were quite different from each other, the flux recovery ratio still retained on a high level, while the rejection ratios were all higher than 90%, and the polysaccharide was proved to be the major pollutant during ultrafiltration.Based on the study of simulative system, we introduced ultrafiltration to refinement of Traditional Chinese Medicine Jinqi Jiangtang Pian, including Rhizoma Coptidis, Radix Astragali and Flos Lonicerae Japonicae. In order to investigate the applicability of PES/Pluronic F127 antifouling membranes in real medicine system, the ultrafiltration performances of three raw materials and their mixtures were all measured, respectively. The results revealed that the application of antifouling ultrafiltration membranes in refinement could effectively separate and purify Berberine, AstragalosideIV and Chlorogenic acid from Rhizoma Coptidis, Radix Astragali and Flos Lonicerae Japonicae, respectively. Meanwhile, the clarity of solutions could be improved as well as the suspended solids could be eliminated. Finally, the inherent relationship between medicine solutions and antifouling membranes was studied; and the guidance for rational design of new process based on ultrafiltration was tentatively presented.