Study Of Antibacterial Polyethersulfone Ultrafiltration Membrane

While the Polyethersulfone（PES） is a good high-temperature-resistant ultrafiltrationmembrane material with good chemical stability and mechanical property. Its hydrophobicnature and low anti-fouling capacity limited its practical application. In this article we adoptedPES as the membrane material,using blend modification method to improve the performanceof PES with the nano-titanium dioxide, chitosan, nano-silver and nonivamide as antibacterialagents and studied the pure water flux, rejection rate, contact angle and structure of themembrane by blending modification, discussed the antibacterial activity and anti-pollutionproperty by testing of it.Firstly, the effects of solvents, content of Polyethylene glycol400, coagulation bathtemperature on the membrane structure and performance were discussed. PES content of14wt%PEG400content of14wt%, coagulation bath temperature to30℃were selected as thebest preparation PES ultrafiltration membrane conditions, the water flux was220.94L/m2hand the rejection rate was82.37%.Based on the optimized technological conditions, adding several antibacterial agents forresearch, the results showed that:（1）The rejection rate of membrane was increased after adding nTiO₂. The pure water fluxincreased and then decreased as the content of nTiO₂rising.When the content of nTiO₂was2wt%, the pure water flux of membrane reached to355.89L/m2h. With stirring temperatureincreased, the water flux increased and then decreased, the rejection rate showed the oppositetrend. Considering, suitable preparation conditions with2wt%nTiO₂and stirring temperatureof80℃was chosen，and the pure water flux of membrane was342.04L/m2h, the rejectionrate was80.89%, it had obvious effect to E. coli.（2）Carboxymethyl chitosan had a good hydrophilic property, its pure water flux wasmuch higher than the ultrafiltration membranes of the modified chitosan derivatives.Stirringtemperature had more effect on pure water flux and little effect on rejection rate. The size ofaperture of PES ultrafiltration membrane which modificated by chitosan and carboxymethylchitosan became bigger, the finger structure aligned, sponge structure was existed near thesurface of membrane, pollution resistance had very good improvement.Considering, suitable preparation conditions with0.3wt%carboxymethyl chitosan and stirring temperature of80℃was chosen, and the membrane pure water flux was745.22L/m2h, the rejection rate was54.79%, it had highly antibacteria effect to E. coli..（3）As content of nAg increasing, the water flux increased and then decreased, therejection rate showed the opposite trend. Membrane performance was greatly influenced bythe mixing temperature. The suitable stirring temperature ranged from70to80℃.Considering, suitable preparation conditions with0.5wt%nAg and stirring temperature of80℃was chosen, and the membrane pure water flux was324.84L/m2h, the rejection rate was72.69%, it was found that the antibacteria effect on E. coli was the best.（4）Adding nonivamide as antibacterial agent, it was found on ultrafiltration membranewith blending modification that: with content of nonivamide increased, the water fluxdecreased, and little effect on the rejection rate of membrane.Considering,0.5wt%nonivamide was chosen to be thesuitable preparation condition, and the membrane pure waterflux was80.54L/m2h, the rejection rate was89.40%. Membrane of E. coli antibacterialeffect was remarkable.Comprehensive analysis of ultrafiltration membranes with optimal process parameters:under the condition of same content of antibacterial agents,it can be seen the bacteriostaticeffect on E.coli: nAg>nonivamide>nTiO₂>CMC>PES.Comprehensive analysis of all, the pure water flux of membrane of CMC/PES is highest,710.58L/m2h; the performance of nAg/PES and nTiO₂/PES are similar, the rejection rate ofmembrane of nTiO₂/PES is higher than that of nAg/PES;the initial pure water flux ofnonivamide/PES membrane is lowest, while the rejection rate of membrane is highest.Membrane surface contact angle from largest to smallest order: nAg/PES>CMC/PES>nTiO₂/PES>nonivamide/PES>PES; Membrane resistance increased coefficient for small tolarge order: nTiO₂/PES<CMC/PES<nAg/PES<nonivamide/PES<PES. while it also could beobtained from the flux attenuation curve that: the PES ultrafiltration membrane decayed fast,it was needed long time for flux to reach the constant. The initial flux of CMC/PES membranewas highest and the attenuation speed faster; however the initial flux of membrane of nAg/PES and nTiO₂/PES were high, the flux of nAg/PES attenuated faster than flux ofnTiO₂/PES;the initial flux of nonivamide/PES membrane was lowest,and it could be increased by improving hydrophily of nonivamide.