Preparation Of Polyamide Composite Nanofiltration Membrane And Its Applicationin Industrial Wastewater Treatment

The nanofiltration membranes(NF)is a type of pressure-driven membrane with properties in between reverse osmosis(RO)and ultrafiltration membrane(UF).It is widely used in seawater desalination,desalting and concentration,starch sugar purification and concentration,industrial wastewater treatment and reuse,and it is a research hotspot of membrane technology.The problem of low water flux exists in nanofiltration membranes,which limits the application of nanofiltration membranes.Therefore,the preparation of NFmembrane with high flux and high separation performance is a hot topic.However,most of the high flux nanofiltration membranes are prepared by optimizing the separation process,but the study of the effect of the substrate membrane on the performance of the nanofiltration membrane is shortage.In this paper,the nanofiltration membrane was prepared by interfacial polymerization,Piperazine(PIP)and trimethylammonyl chloride(TMC)were used as two phase monomers.Preparation of high flux polyamide composite nanofiltration membrane by the regulation of the substrate membrane and the optimization of the interfacial polymerization conditions.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)were used to characterize the morphology and structure of the membranes.It was found that adding polycyclic sulfone membrane materials,adding hydrophilic organic compounds,and using sponge like pore structure could enhance the flux of nanofiltration membrane.Furthermore,the effects of monomer concentration,additives,concentration and reaction time on the performance of nano filtration membrane were investigated.The experimental results show that the polyamide composite nanofiltration membrane has good separation performance and high throughput.The hydrophilic organic matter was added to the basement membrane,which enhanced the hydrophilicity of the membrane surface and improved the structure of the polyamide layer.Compared with the finger like pore ultrafiltration membrane,the pore structure of the sponge like pore is increased,and the pressure resistance is greatly improved.In the aqueous phase,the concentration of the monomer is 1.0wt%,the concentration of sodium alkyl sulfonate(SDS)is 0.06wt%,the pH value of the aqueous solution is 9.5,the time of the water phase is 10 min,the nanofiltration membrane is prepared by the reaction time of the interfacial polymerization of 1 min;the temperature of the liquid is 25,and the operating pressure is 0.6MPa,the flux of nanofiltration membrane reaches 63.9 L·m-2·h-1·MPa-1,the retention rate of magnesium ion is 92.9%,and the retention rate of sodium ion is 31.0%.The results showed that nanofiltration membrane had good resistance to contamination and chlorine tolerance.Further,the nanofiltration membrane can be used to treat industrial wastewater.The COD can be reduced to 10.0 mg·L-1,the total hardness of water will be reduced to 100.0 mg ·L-1,and the treated water will be of good quality.