Fabrication And Performance Study Of Modified Polyamide Nanofiltration Membrane With Nh₂-functionalized Silica Nanoparticles

Polyamide thin film composite（TFC）nanofiltration（NF）membranes are the mainstream of NF membrane products.With advantages of high mechanical strength,good hydrophilicity,high chemical stability,NF membranes have been widely applied in several areas including water treatment,food industry,power,medicine and so on.However,there are also some problems such as low permeation flux,flux attenuation and membrane fouling during the practical application of NF membranes,to solve these problem,this paper studied on the surface hydrophilic modification of commercial NF membrane and the design of new nanocomposite membrane with the hydrophilic SiO₂nanoparticles,respectively.Specific content as follows:This paper proposed a novel surface hydrophilic modification method of polyam-ide NF membrane.Firstly,the SiO₂ NPs were modified with silane coupling agent,which could introduce amino groups to the surface of SiO₂ NPs,then,the EDC/NHS were used to activate the carboxyl groups,which could introduce the semistable amine-reactive NHS ester,finally,the amino group on the NH₂-SiO₂ NPs were able to react with the NHS ester to form amide bond,which attaching the NH₂-SiO₂ NPs onto the surface of the membrane via chemical bonds.Through optimization,the water flux and salt rejection rate were well maintained compared with the pristine membrane,the water contact angle is 15°.The antifouling property of the membrane was significantly en-hanced with the BSA and CTAB as model foulants,the water flux recovery ratio of the membrane was 92%and 87%,respectively.This paper also developed a novel nanocomposite NF membrane fabrication strat-egy.Firstly,the NH₂-SiO₂ NPs were in-situ embedded on the surface of PSF substrate to form NH₂-SiO₂ NPs hydrophilic layer.On this basis,the interfacial polymerization process was conduct to fabricate polyamide nanocomposite NF membrane（NH₂-SiO₂-TFN）.Under optimal preparation conditions,the water flux and reasonable salt rejec-tion were 59.7 L/（m²·h）and 97.3%,respectively.The water flux was improved about6.2%compared to that of contrast NF membrane（Contrast-TFC）,which was fabricated under same interfacial polymerization condition.In addition,the NH₂-SiO₂-TFN also showed good structure stability and antifouling property.