| The pervaporation separation of aromatic/aliphatic hydrocarbons can be widely used in the petrochemical industries and environment protection.The“pore-filling”composite membranes were successfully fabricated by the double-plasma grafting strategy,which were analyzed by pervaporation of toluene/n-heptane mixtures.The mass transfer mechanism was preliminarily explored by molecular dynamics simulation and adsorption experiments.The double-plasma grafting strategy was performed to prepare the pervaporation composite membrane with“pore-filling”structure by using PEO500OHMA and MePEO500MA as monomers.The macromolecules(PEO500OHMA/MePEO500MA)were plasma graft-filling polymerized onto and into the porous polyacrylonitrile ultrafiltration membrane.Attenuated total reflection fourier transform infrared spectroscopy,field emission scanning electron microscopy and atomic force microscope were used to characterize the composite membrane.The selective top layer of PAN/PEO500OHMA composite membrane was less thicker than that of PAN/MePEO500MA composite membrane and the surface of PAN/MePEO500MA was less rougher.The separation factor and permeate flux of PAN/PEO500OHMA composite membrane were 9.08 and 1.09 kg/(m~2·h),respectively;while PAN/MePEO500MA had the separation factor and permeate flux were separately 2.17 and20.84 kg/(m~2·h).Molecular dynamics(MD)simulation was used to study the diffusive properties of toluene and n-heptane in the PEO500OHMA homopolymers and MePEO500MA homopolymers,respectively.The values of diffusion selectivity of PEO500OHMA homopolymers were nearly 1,while the MePEO500MA homopolymers favored the diffusion of n-heptane over toluene.According to the adsorption isotherms,the sorption selectivity of PEO500OHMA homopolymers was greater than that of MePEO500MA homopolymers.Therefore,for the composite membranes investigated herein,it was sorption selectivity that largely determined the pervaporation performance for aromatic/aliphatic separation. |
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