Solvent Permeation And Transport Mechanism Of PDPA Solvent Resistant Nanofiltration Membrane

As a potential solvent resistant nanofiltration (SRNF) material, poly(diphenyl acetylene) (PDPA) has excellent thermostability, ultra-high gas permeability and is insoluble in any common organic solvents. In this work, the permeation of common organic solvents and the retention of roxithromycin of PDPA were investigated. In addition, the solvent transport was studied.PDPA dense membranes were successfully prepared by desilylation of poly[1-(4-trimethyl silyl)phenyl-2-phenyl acetylene] (PTMSDPA) membranes with trifluoroacetic acid. The ethanol permeate flux of ethanol was stable. With the increase of temperature, the solvent permeate flux increased obviously. Meanwhile, the effect of temperature on permeate flux of ethanol could be well correlated by the Arrhenius plot.The ratio of flux/viscosity activation energy (EJ/E?) was 1.19, which implied that the solvent transport of PDPA membrane could not described solely by the pore-flow model. For the twelve kinds of common organic solvents, the permeation behaved in the similar way to ethanol.The spearmen correlation coefficient (rs) was applied to analyse the solvent permeation of PDPA and their physicochemical properties (viscosity, degree of swelling, molar volume, dielectric constant, membrane-solvent surface tension and membrane-solvent solubility parameter). It was found that for alcohol homologue, the influence of physicochemical properties are obviously. That is to say, it was unable to resolve the more important one. For different kinds of solvents, the permeate flux was affected by all physicochemical properties studied herein. The rs values of membrane-solvent solubility parameter difference, viscosity and, and degree of swelling were larger. The flux was significantly correlated with these parameters at P level of 0.01,0.05 and 0.1, respectively. Therefore, membrane-solvent solubility parameter difference, viscosity and degree of swelling were identified as the main factors affecting flux of the PDPA membrane. According to the regression analysis, it was found that the models based on the pore-flow mechansim could describe the mass transfer of alcohols. However, the models studied herein were not applicable in non-alcohol solvents. The mass transfer could not describe solely by eith of pore-flow or solution-diffusion.Roxithromycin retention was evaluated. The rejection of roxithromycin were about 97%. Compared with traditional purification technologies (vacuum distillation/recrystallization), PDPA SRNF with higher separation efficiency, could be a new potential separation technology for roxithromycin purification.