Structure Control Of Polv(vinvl Imidazole)Gel Composite Membranes For Dye Removal From Water

The emission of dye wastewater poses a great threat to both the survival of animals and.plants.Therefore,the problem of decolorization of dye wastewater is urgent to be solved.In this thesis,poly(vinyl imidazole)(PVI)gel composite porous membrane was quickly and simply prepared for rapid adsorption and separation of dyes by crosslinking.The full text of the specific research and main conclusions are as follows:The gelation mechanism of PVI and armmonium persulfate(APS)were proposed.we tend to hold that PVI and APS form a redox initiation system and generate free radicals to initiate PVI to crosslink.The discovery of this phenomenon makes the combination of PVI and membrane not limited to the graifting method,which will increase the application of PVI.PVI gel was introduced onto the microfiltration membrane through in-situ cross-linking with the assistance of APS.After optimizing reaction conditions.The load reached 9.7%and the isoelectric point(IEP)is 8.3.Because it is positively charged,the modified membrane can not only be used to deal with anionic dye wastewater,but also separate anionic dyes from cationic ones.When the permeation flux increased to 500 L/m2 · h,the adsorption capacity of sunset yellow remained 79mg/g(the removal efficiency is higher than 99%).This flux is much greater than that of nanofiltration and ultrafiltration membranes which exhibite the same adsorption capacity.In addition,the modified film exhibites excellent stability in both strong acid and base.The desorption efficiency is 100%.In order to enhance the charge of PVI gel,increase its load on the substrate,and improve the flux and treating capacity,PVI was immobilized onto the membrane by quaternation crosslinking.After optimization,the load reached up to 28.9%and the IEP increased to 10.8.When the permeation permeation flux increased to 1000 L/m2 "h,the treating capacity of sunset yellow remained unchanged.Similarly,the PVI gel can be stabilized with the substrate under the condition of strong acid and base.The prepared gel composite membrane combining adsorption and membrane process maintains excellent treating capacity towards dyestuffs even at high flux.It provides new functional materials for dye removal and recycling in dye wastewater.