Preparation And Properties Of Blending Modified Polysulfone Ultrafiltration Membranes Based On Sulfonated Polysulfone

With the rapid growth of population and development of industry,the world is facing the shortage of water resources and serious pollution of water environment.The traditional separation technology is difficult to meet the current wastewater treatment requirements.Membrane separation technology has the advantages of high efficiency,energy saving,environment friendly and simple filtration process,which has become the fastest developing separation technology in recent years.Among them,ultrafiltration technology is more mature and widely used in the field of water treatment due to its low operating pressure and large permeation flux.Polysulfone materials have excellent chemical stability and film-forming properties,so they are often used to prepare ultrafiltration membranes.However,their strong hydrophobicity affects the separation efficiency and pollution trend of membranes,which limits their further development.Therefore,this paper aims to improve the hydrophilicity of polysulfone membrane materials by introducing hydrophilic polymers and hydrophilic polymer nanoparticles with similar structures to prepare ultrafiltration membranes with excellent permeability and antifouling properties..Firstly,the traditional dichloro monomers were sulfonated,and then a series of sulfonated PSF-SO₃Na copolymers were prepared by controlling the feed ratio through the polycondensation reaction,and hydrophilic sulfonic acid groups were successfully introduced into the main chain of PSF.Sulfonated copolymers were mixed in polysulfone at different ratios,and a series of polysulfone ultrafiltration membranes were prepared by impregnation-precipitation phase transformation.The results of water contact angle test,scanning electron microscopy,porosity and average pore size test showed that the surface hydrophilicity,average pore size and porosity of the membrane increased with the increase of sulfonated copolymer content.The results of the cyclic ultrafiltration experiment showed that compared with the PSF ultrafiltration membrane,the ultrafiltration membrane permeability and anti-pollution performance of the blend sulfonated polysulfone copolymer were significantly improved.Especially when the content of sulfonated polysulfone copolymer is 30%without PVP,the water flux of the ultrafiltration membrane can reach 291.9 L/（m²?h）,which is 6.2 times of that of the PSF membrane.The flux recovery rate is 71.9%,and the BSA retention rate is also maintained at 98.7%.The polar group-SO₃^-in sulfonated polysulfone copolymer can form hydrogen bonds with water molecules on the membrane surface,attract water molecules and improve the hydrophilicity of the membrane surface,so the permeability and antifouling properties are significantly improved.Then,the PSF-SO₃Na synthesized in the previous step was combined with hydrophilic polyethyleneimine to prepare polymer nanoparticles by in situ self-assembly in polysulfone solution through the electrostatic attraction of amino and sulfonic groups.A series of modified ultrafiltration membranes were prepared by impregnation-precipitation phase conversion.The existence and distribution of polymer nanoparticles can be obtained in TEM and SEM.The process of in situ self-assembly makes it dispersed evenly on the membrane matrix and surface.The introduction of polymer nanoparticles effectively improved the hydrophilicity of the membrane surface,and the average pore size and porosity of the ultrafiltration membrane were improved.The results of cyclic ultrafiltration show that the permeability and anti-fouling properties of ultrafiltration membrane are improved by the introduction of polymer nanoparticles.When the content of polymer nanoparticles is 3 phr,the water flux reaches 391.0 L/（m²?h）,which is 2.2 times of that of film,the flux recovery rate is 61.9%,the rejection rate is above 90%,and the comprehensive performance is relatively excellent.