Studies Of Cyclodextrin Derivatives/Cellulose Acetate Blending Nanofiltration Membrane

Nanofiltration membrane is modern membrane separation technology with unique separation performance,which has been widely applied in water-softening,desalination,food processing,bio-pharmaceutical and many other fields.The improvement of separation performance of nanofiltration has been one of the research focus.In this study,we synthesized two cyclodextrin derivatives(cyclodextrin polymer and cyclodextrin inclusion compound)using ?-cyclodextrin as the starting material.The synthesized cyclodextrin derivatives were blended into CA as additives,then the effects of the addition of these two cyclodextrin derivatives on the structure and the properties of the CA nanofiltration membranes that prepared by phase inversion method were investigated.In this study,P-cyclodextrin is used as the starting material to react with 2-bromo-isobutyryl bromide for obtaining the macromolecular initiator(21-Br-P-CD);star-shaped polymer Poly(HEMA-co-MMA)was synthesized through SET-LRP polymerization using 21-Br-?-CD as initiator;then the resulting Poly(HEMA-co-MMA)were blended with cellulose acetate(CA)to prepare the CA/Poly(HEMA-co-MMA)blend nanofiltration membrane through phase inversion method.The effects of polymer composition,polymer content and operating conditions on the properties of the Blend membrane were investigated.It showed that when the monomer ratio was 5:5,the performance date of the blend membrane was the best.The addition amount of Poly(HEMA-co-MMA)increased from 0 wt%to 6.0 wt%,the membrane flux decreased first until reach a plateau(from 25.2 L m-2h-1 to 13.5 L m-2h-1),the rejection of Na2SO4 increased first and then leveled off(from 68.8%to 94.0%).In this study,we prepared triclosan/cyclodextrin inclusion complex(TR-CD IC)with antibacterial activity through saturated aqueous solution method,and then blended TR-CD IC into CA to prepare the CA/TR-CD IC blend nanofiltration membrane.It showed that when the addition amount of TR-CD IC increased from 0 wt%to 5.0 wt%,the membrane flux increased first and then reached a plateau(from 12.9 L m-2h-1 to 22.2 L m-2 h-1),the rejection of Na2SO4 decreased first and then leveled off(from 94.4%to 77.8%).Long-term operational stability experiment showed that TR-CD IC has certain stability in the testing process,which will not easily be lost.The antibacterial experiments showed that the addition of TR-CD IC imparted antibacterial properties to the blend membrane,the inclusion of cyclodextrin prolonged the antimicrobial activities of the antimicrobial agent TR.In this study,the operating conditions of the prepared blend nanofiltration membrane were investigated,the results showed that the resulting nanofiltration membrane was a typical negatively charged nanofiltration membrane.In addition,the structure of Poly(HEMA-co-MMA)was characterized by FTIR,1H NMR,DSC and GPC,the structure of TR-CD IC was characterized by 1H NMR,DSC and XRD.Meanwhile,the morphology and structure of the nanofiltration membrane were characterized by ATR-FTIR,SEM,AFM and contact angle measurement.