LBL Nanofiltration Membrane Made By Hyperbranched Anionic Polymer

Hyperbranched polymers have attracted wild attention in recent years because of their unique structure and physicochemical properties.Nanofiltration technology,as an important component of membrane separation technology,plays an important role in the process of biomass separation.Our purpose of this study is to synthesize a kind of anionic hyperbranched polymer,and use the self-assembly way of making nanofiltration membrane.The membrane is used to glutathione removing,to improve retention and selectivity at high flux.Firstly,we synthesized hyperbranched b-PAMS using AM and AMPS as monomer.The polymer was characterized by IR and NMR,and the degree of branching,molecular weight and molecular weight distribution were measured.The results showed that the anionic monomer AMPS was successfully bonded to the polymer molecular chain,and the synthesized polymer had branched structure.By investigating the effects of different conditions on the formation of b-PAMS,the suitable synthetic conditions were determined:CAM(%wt)=4.7%,AM/AMPS=1,BisAM/CTA=20,CTA/APS=2,T=4h.The Mw of b-PAMS is 6.62 × 105,the DB of b-PAMS is 0.74.Secondly,polysulfone ultrafiltration membranes were synthesized by phase inversion method.The effects of different conditions on the structure and properties of polysulfone membranes were investigated.The composite nanofiltration membranes were prepared by LBL method using b-PAMS and PDADMAC as anionic and cationic polyelectrolytes.Through the characterization of membrane,we can see that the polyelectrolyte is assembled on the membrane,and the membrane surface becomes more compact.By investigating the influence of different factors on the separation performance of GSH,it can be seen that when the concentration of raw material is 25g/L,the concentration of NaCl is 2g/L,and the assembly layer is 3,the LBL composite membrane can achieve a good separation effect.At this time,the flux is 43.7 L · m-2 · h-1,GSH retention is 42.9%,selectivity can reach up to 15.86.Finally,aiming at the shortage of LBL composite membrane stability,using UV crosslinking modification technology,the cationic polyelectrolyte PDADMAC was assembled by UV crosslinking.According to the study of the different UV treatment conditions,the irradiation time 7min,the irradiation distance 18cm,the concentration of cationic electrolyte 25g/L as the appropriate treatment conditions.The stability of the composite film was improved significantly after the stability test.