Preparation Of GO-PVDF Ultrafiltration/nanofiltration Membrane And Its Application In Water Treatment

Due to population growth,economic development and improvement of living standards,water shortage and water polution crisis become environmental challenge in the world.The development of efficient and sustainable water purification technology is of great significance for environmental protection and water resources recycling.In recent years,membrane technology has been widely used in this field because of the characteristics of high precision separation and easy control.Using polyvinylidene fluoride（PVDF）,PVDF ultrafiltration membrane and PVDF nanofiltration membrane by interfacial polymerization.Using Box-Behnken Design（BBD）response surface analysis and optimize the preparation conditions of the membrane,through infrared,contact Angle,scanning electron microscope characterization of diaphragm surface morphology and functional group analysis,finally by removal and strong corrosion resistance experiment,select the performance of excellent ultrafiltration membrane and nanofiltration membrane,provide theoretical reference for the practical application of the membrane.The main contents of this article are shown as follows:1、Optimize the design of PVDF ultrafiltration basement membrane to study the performance of the basement membrane and its application in oily wastewater.Using BBD factorial experiment and condition optimization,the best mass ratio of each component of the ultrafiltration membrane was:PVDF（23%）,polyvinyl pyrrolidone（PVP）（5%,10000Da）and graphene oxide（GO）（0.3%）.The performance results showed that the water flux decreased from 204.61 L/（m²·h）to 186.37 L/（m²·h）with the running time（5min to 120min）and the BSA removal rate increased from96.58%to 97.72%.The higher the concentration and salt content of oily wastewater,the smaller the water flux of the ultrafiltration membrane but the higher the oil removal rate;As the removal rate decreases,the water flux increases and then decreases,in which the water flux is the largest at p H=7.0,and the oil removal rate is96.87%.2、The best PVDF ultrafiltration membrane is used as the base membrane,and the interface polymer filter membrane is used to prepare and optimize the regulation to study the removal of salt ions and corrosion resistance.The results of univariate analysis showed that the best preparation conditions of nanofiltration membrane were piperazine（PIP,0.45%）,benzomeyl chloride（TMC,0.5%）,baking temperature（323 K）and polymerization time（1.75 min）.The water flux was mainly affected by polymerization time,and the divalent salt removal rate was affected by PIP and TMC.In addition,the polyamide group exists on the surface of the nanofiltration membrane compared with the ultrafiltration membrane.The performance test results show that after 30 min,the removal rate efficiency of nanofiltration membrane to monovalent,bivalent and trivalent salt is 42.38%,75.63%and 87.15%respectively.In addition,the nanofiltration film has good corrosion resistance.Compared with the initial film,sodium hypochlorite（0.03%）soaked for 30 days,the water flux slightly increased from 34.91 L/（m²·h）to 46.15 L/（m²·h）,the salt cut rate slightly decreased from 91.37%to 87.64%;after 3000 mg/L Na Cl and Mg SO₄salt solution soaked for30 days（33.82 L/（m²·h）to 43.87 L/（m²·h））,and the salt cut rate slightly decreased（91.15%to 85.72%）.