Preparation And Modification Of Thin-film Composite Aromatic Polyamide Forward Osmosis Membranes Via Click Chemistry

Forward osmosis technology is widely used in the field of sea water desalination,sewage treatment,energy production,food processing and many other fields.Thin-film composite aromatic polyamide membrane,which is the core component of FO,is a kind of widely used polymer separation membrane.However,due to its larger membrane pore and relatively hydrophobic,the traditional composite film can cause the internal concentration polarization(ICP)of the film,reducing the antifouling performance and service life of the composite film.Methods for hydrophilic modification of aromatic polyamide composite thin films include physical and chemical modification.However,these methods are complex,high cost and effect does not last for a long time.This study is to prepare and modify the thin-film composite aromatic polyamide forward osmosis membranes via click chemistry at the same time.Polyethylene glycol mono methyl ether(MPEG)is hydrophilic,moist,lubricant and physiological inert and mild.So we can take the MPEG into the casting solution,the support membrane for the aromatic polyamide composite films were then prepared and modified at the same time.This study is to prepare and modify the thin-film composite aromatic polyamide forward osmosis membranes via click chemistry,mainly comprising the following steps:(1)Preparation of the propargyl poly(ethylene glycol)s(MPEG-CoCH);(2)Chloromethylation and azidation of the PSf(PSf-CH2N3);(3)Preparation of the casting solution(MPEG-PSf)via click chemistry;(4)Preparation of the PSf support layer by non solvent induced phase separation;(5)Preparation of the polyamide active layer through interfacial polymerization on the porous PSf support membrane.Characterizations of FT-IR(Fourier transform infrared spectroscopy),nuclear magnetic resonance(1 H NMR),SEM,EDX confirmed the preparation and the modification.After the modification,the porosity and the pure water flux of the PSf support was sharply increased;the best pure water flux is gained for the MPEG-400 modified membrane.In the reverse osmosis(RO)system,the water flux increased significantly,while the rejection to the salt is not obvious.In the forward osmosis(FO)system,pure water flux and solute flux increased significantly and the support layer structure parameter(S)is decreased.