Preparation Of The TCPP/PSF Ultrafiltration Membrane And Research Of Its Performance

It is well known that ultrafiltration membranes play an important role in seawater desalination and sewage treatment.The main reason is that the ultrafiltration（UF）membrane has the high pure flux and high rejection rate for these contaminants under low pressure conditions.However,the UF membrane antifouling and flux need to be further improved.Some porphyrin compounds have good hydrophilicity,and it is protonated under strong acidic conditions and then forms strong hydrogen bonds,thereby achieving the purpose of modifying the UF membrane.So in this paper,the porphyrins and polysulfone base membrane were chosen as the research objects to prepare high-flux and high-rejection porphyrin/polysulfone UF membranes by a method similar to interfacial polymerization.First,three symmetric porphyrin compounds which are 5,10,15,20-tetrakis（4-carboxyphenyl）porphyrin（TCPP）,5,10,15,20-tetrakis（4-aminophenyl）porphyrin（TAPP）and5,10,15,20-Tetrakis（4-methoxycarbonylphenyl）porphyrin（TPPCOOMe）were successfully synthesized.Then the phase inversion method was used to prepare polysulfone（PSF）base membranes,and two common using hydrophilic additives which are polyethylene glycol 600（PEG-600）and polyvinyl pyrrolidone K30（PVP-K30）were used to modify the base membranes.Through the membrane performance test,it was found that when the content of the additives was constant,the pure water flux of the base membranes decreased as the content of the polysulfone resin increased,and the rejection showed an opposite trend.When the content of the polysulfone resin is constant,the two hydrophilic additives showed different results for the membrane separation performance.By comparison,the additive of PEG-600 was better than the PVP.When both PSF and PEG-600 concentrations are 22%,the separation result of the membrane showed the best,which the rejection rate was 98%and the pure water flux was 455Lm^-2h^-1bar^-1.Next,NaHCO₃ was first used to dissolve TCPP and TMC（trimesoyl chloride）was used to produce a strong acid.Then TCPP was modified in a membrane with a different rejection rate by a new method similar to interfacial polymerization.The strong acid produced by the hydrolysis of TMC promotes protonation of TCPP,so that TCPP would be well anchored in the membrane.Then modified membranes were analyzed,showing that the TCPP was protonated and evenly distributed within the pores of the membrane.Tests on membrane separation performance show that for a membrane with a high BSA（bovine serum albumin）rejection,when the ratio of Na HCO₃ to TCPP is 16:1（wt.%）,the pure water flux of membrane Z1 16:1is increased by 34%(from 455 to 614 Lm^-2h^-1bar^-1)while the membrane rejection was maintained above 95%;for membranes with low BSA rejection membrane,when the ratio of Na HCO₃ to TCPP was 32:1,the rejection of membrane B2 32:1 was found to increase from 81%to 96%,although the membrane flux decreased,it remained at 638 Lm^-2h^-1bar^-1,which is the best experimental result of the known polymer ultrafiltration membrane.This dual results are attributed to the synergistic effect of protonated TCPP and Na HCO₃,where the former increases the membrane flux and the latter increases the membrane rejection rate.Finally,the anti-fouling of membranes was characterized and find that the protonated TCPP membranes can improve the membranes anti-fouling.