Preparation And Properties Of Nano-TiO₂/PI/PP Solvent Resistant Nanofiltration Membrane

Solvent nanofiltration membrane can be used in the treatment of non-aqueous system and aqueous solution rich in organic solvents,and its solvent resistance has broken the application boundary of water system application membrane.For the asymmetric composite membrane,the interface polymerization has obvious advantages over other preparation methods.For nanofiltration hybrid membrane,the introduction of nanoparticles by in-situ synthesis method also has obvious advantages.Nano-TiO₂/polyimide/polypropylene composite nanofiltration membrane was prepared by interfacial polymerization and in-situ synthesis.First of all,with pyromellitic dianhydride?PMDA?as reactants,sulfoxide chloride?SOCl₂?as the acylchloride reagent,N,N'-dimethyl formamide?DMF?as the catalyst,reflux reaction 6 h under 80?,get1,2,4,5-benzenel tetracarbonyl chloride?BTC?products.After atmospheric distillation and vacuumdistillation,the purified isobenzoyl chloride was obtained.The structure of BTC was verified by Fourier transform infrared spectroscopy?FTIR?and nuclear magnetic resonance(¹³C-NMR).Then based on the work of experimental group before,base of hydrophobic polypropylene membrane?water contact Angle is about 121°?for hydrophilic modification.Finally,got a hydrophilic PP membrane with water contact angle about 42°.In addition,the nano-TiO₂/PI/PP solvent composite nanofiltration membrane was prepared by the combination of interfacial polymerization and in-situ synthesis.Attenuated total reflection flourier transformed infrared spectroscopy and SEM are used to characterize the composition and morphology of composite membrane surface.The flux and rejection of the composite membrane were tested by using1000mg/L of polyethylene glycol as the test solution and under the pressure of0.5MPa.And then studyed the influence of thermalimidization temperature,thermal imidization time,copolymerization-TMC and in-situ synthesis introduction of TiO2on the influence of membrane structure.The results showed that:when the thermalimidization temperature is 70?,thermal imidization time is 10 min,organic phase monomer mass concentration for TMC to BTC is 6:4,the resulted membrane with excellent performance which has a flux of 57.94 L/?m2,h?and rejection of92.43%.When thecontent of TBOT in aqueous phase is 0.3?v/v?%,the maximum flux is 297.137 L/?m²·h?,which is five times than that without nano TiO₂ nanofiltration membrane.When the content of TBOT in organic phase is 0.3?v/v?%,the maximum membrane flux is 187.34 L/?m²·h?,and nearly four times as much as the noneTiO₂nanofiltration membrane.Finally,as for the solvent resistant of nanofiltration membrane,it was immersed in8 types solvent for 15 days,such as methanol,DMF,NMP.After immersed in solvent,the flux and rejection was tested by PEG solution and rhodamine B methanol solution.Results show that the solvent resistant of membrane is excellent.But the solvent resistance of nanofiltration membrane prepared by in-situ synthesis?aqueous phase?is better than that of nanofiltration membrane prepared by the method of in-situ synthesis?organic phase?.