| At present,commercial composite reverse osmosis membranes usually use polysulfone（PSF）as the support layer material.This composite membrane has good performance at room temperature,but cannot be used at high temperature due to the limitation of thermal properties of polysulfone.In this paper,poly（phthalazinone ether sulfone ketone）（PPESK）with excellent heat resistance was used as support membrane material to prepare high temperature resistant composite reverse osmosis membrane.By optimizing the interfacial polymerization process,introducing additives,and modifying PPESK support membrane by hydroxylation,a composite reverse osmosis membrane with better performance was obtained.The specific content is as follows:（1）Using PPESK as membrane material,N-methylpyrrolidone（NMP）as the solvent and ethylene glycol methyl ether（EGME）as the additive,the PPESK porous membrane was prepared by the immersion precipitation phase inversion method.By optimizing the composition of the casting solution and the film-making conditions,determined the best film-making process,namely,the PPESK content of 22 wt%,the EGME content of 17 wt%,the NMP content of 61 wt%,the temperature of 15℃,the humidity of 32%,and the temperature of the gel bath was 12°C.The PPESK ultrafiltration membrane prepared accordingly has a molecular weight cut-off of 60 KDa and a pure water flux of 200 L/（m2·h）,which is used as the support membrane of the composite membrane.（2）Based on PPESK support membrane,m-phenylenediamine（MPD）and trimesoyl chloride（TMC）were used as water and organic phase monomers to prepare PPESK composite reverse osmosis membrane by interfacial polymerization method.We investigated the effects of monomer concentration,monomer impregnation time,heat treatment temperature and heat treatment time on the performance of composite reverse osmosis membranes.The results showed that when the MPD concentration was 2 wt%,the TMC concentration was 0.15 wt%,the water phase immersion time was 2 min,the organic phase immersion time was 1 min,the heat treatment temperature was 95°C,and the heat treatment time was 3 min,the prepared PPESK composite reverse osmosis membrane has good separation performance.The separation performance of the prepared composite reverse osmosis membranes under different salt species,different operating pressures and different operating temperatures was further investigated.It was found that the PPESK composite reverse osmosis membrane had the best retention effect on Na2SO4,and the desalination rate reached 98%;as the operating pressure increased from 0.8MPa to 2.4 MPa,the salt rejection of the composite membrane remained above 98%,and the water flux increased from 3.4 L/（m2·h）to 11.5 L/（m2·h）;as the operating temperature increased from 25°C to 75°C,the salt rejection rate of the composite membrane remained around 98%,and the water flux increased from 10.2 L/（m2·h）to 30.4 L/（m2·h）.（3）The effects of additives on the properties of PPESK composite reverse osmosis membranes during interfacial polymerization were investigated.As the content of dimethyl sulfoxide（DMSO）in the aqueous phase increased from 0 wt%to 2 wt%,the salt rejection of the composite membrane decreased from 96%to 92%,and the water flux increased from 7.3L/（m2·h）to 19.6 L/（m2·h）;as the content of 4-dimethylaminopyridine（DMAP）in the aqueous phase increased from 0 wt%to 0.2 wt%,the salt rejection of the composite membrane decreased from 96%to 90%,and the water flux decreased from 7.3 L/（m2·h）increased to 22.0 L/（m2·h）;as the content of benzyltriethylammonium chloride（TEBAC）in the aqueous phase increased from 0 wt%to 2 wt%,the salt rejection of the composite membrane increased from 96%to97%,and the water flux increased from 7.3 L/（m2·h）rise to 10.0 L/（m2·h）.The diffusion process of MPD was simulated by MS software,and it was found that the diffusion coefficient of MPD was slightly different under different interfacial polymerization systems,and the results were DMPD-DMSO-TMC>DMPD-TMC>DMPD-TEBAC-TMC>DMPD-DMAP-TMC.Based on the experimental and simulation results,TEBAC as a water-phase additive can improve the performance of PPESK composite membrane the best.（4）The effect of hydroxylation modification on the properties of composite reverse osmosis membrane was investigated.The PPESK-OH support membrane was obtained by hydroxylation of the PPESK support membrane with sodium borohydride（Na BH4）.We investigated the effect of modification time on the support membrane and found that the water contact angle of the support membrane decreased from 89.61°to 65.84°with the hydroxylation modification time from 0 min to 20 min.The PPESK-OH composite reverse osmosis membrane was prepared based on the modified PPESK-OH support membrane.It was found that with the modification time from 0 min to 20 min,the salt rejection rate of the composite membrane remained around 97%,and the water flux increased from 9.1 L/（m2·h）to 16.4 L/（m2·h）.At the same time,we investigated the performance of PPESK-OH composite reverse osmosis membrane under different salt types,different operating pressures and different operating temperatures.It is found that the PPESK-OH composite reverse osmosis membrane has the best retention effect on Na2SO4,and the salt rejection rate reaches 97%;as the operating pressure increased from 0.8 MPa to 2.4 MPa,the salt rejection of the composite membrane remained above 97%,and the water flux increased from 5.6 L/（m2·h）to 18.5 L/（m2·h）;as the operating temperature increased from 25°C to 75°C,the salt rejection rate of the composite membrane remained around 97%,and the water flux increased from 16.8 L/（m2·h）to 41.2 L/（m2·h）. |
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