Experimental Study And Theoretical Calculation Of Removal Of Benzene From Water Using PMPhS Pervaporative Membrane

Pervaporation, as a novel liquid mixture separation technology, has outstanding technical advantages and promising application prospects in the removal of trace volatile organic compounds (VOCs) from water. Separation performance of pervaporation process mainly depends on the property of membrane. Selecting the appropriative material with excellent separation performance is an important issue in pervaporation research. Study on the mass transfer of the process will give more guidance on the development of membrane and optimisation of the process.In our work, we chose the PMPhS as the special material considering the solution parameters and chemical structures and two kinds of membranes, 108-1 and JHG-GT-1 membrane with 5.48% and 20% benzyl group content respectively, were prepared. Influences on the preparation and performance of membranes by the benzyl group content, portion of solvent, cross linker and catalyst were experimentally investigated and discussed.Many techniques were used to analyze and characterize the physical and chemical structures and poverties. Information of functional groups in membranes was given by FT-IR; Surface element compositions were gained by XPS analysis; Affinities between membrane and the liquids were evaluated by contact angle measurement; Morphological analysis were given by SEM spectra; Membrane surface roughness information were obtained by AFM; Crystallization degree was determined by XRD.Influences of feed temperature, Re, permeate pressure and feed concentration on the total flux, component flux, separation factor and PSI of the two kinds of membranes were studied. Experimental results show that the separation factors of 108-1 and JHG-GT-1 are 2862 and 4220 respectively, and total fluxes are 98 and 293 g/m2·h. PMPhS membranes can remove the dilute benzene from aqueous solution effectively and show better separation performance than the other membranes mentioned in literatures.A full predictable model for the pervaporation process was proposed based on solution-diffusion mechanism. The calculated values and experimental results were compared. The activity of components in feed phase () was calculated by original UNIFAC, and the activity of solvent at membrane interface () by modified UNIFAC. From swelling equilibrium, the volume fractions of the components absorbed at the membrane interface of feed side were determined by least-square minimization, which is minimization of the objective function, . The diffusion coefficient was determined by the free-volume theory of transport developed by Fujita. When the temperature was below 330K and feed concentration was less than 0.0013gbenzene/gwater, the absolute values of the relative errors for benzene flux were fewer than 54%. The relative errors for benzene flux increased with the rise of temperature and feed concentration, whereas no significant change appeared to the relative errors for water flux. The calculated values of flux and separation factor are consistent with the experimental ones.