The Influence Of Regulation Of Interficial Polymerization On The Characteristics Of Nanofiltration Membrane And Trace Organics Rejction

Nanofiltration（NF）membrane is often used for the rejection of trace organic in sewage and reused water,and is of great application significance to ensure the water safety.As one of the commonly used methods of NF membranes preparation,interfacial polymerization is deemed as an efficient process,which is very simple and easy to implement.Howerer,the mechanism and impact factors are not clearly for the membrane characterization and trace organics rejection.Therefore,this thesis focused on the influence of the interficial polymerization regulation process on the membrane performance and trace organics rejection.In this thesis,through the interfacial polymerization process,we designed and regulated the surface based on the as-prepared membrane,and further studied the characterization of the corresponding products and effect on the removal of trace organics.（1）Different mass fractions of PVA were added to the interficial polymerization to reduce the diffusion rate of the aqueous solute PIP.After interficial polymerization with the oil phase TMC,the water flux,salt rejection rate,trace organic matter rejection rate were tested,which influenced membrane surface structure and membrane pores.（2）Different mass fractions of PEI were added to the interficial polymerization,which introduce positively charged groups as an aqueous phase additive,participate in the polymerization reaction of PIP and TMC,and affect the interficial polymerization products.Water flux,salt rejection rate,trace organic matter rejection rate were tested.（3）The PVA with a mass fraction of 1.04 wt%was added to the interficial polymerization.After it reacted with TMC,different mass fractions of PEI were added to the interficial polymerization.The water flux,salt rejection rate,trace organic matter rejection rate were tested.The experimental results indicated that:（1）With the increase of the mass fraction of PVA,the surface of the NF membrane changed from spots to stripes,the membrane pore size and the water flux becomed larger,the salt rejection rate decreased.Compared with the membrane without PVA addition,the water flux of NF membrane with 1.04 wt%PVA increased by 1.4 times,the rejection rate of Na Cl decreased by60.2%,the rejection rate of Mg SO₄ decreased by 90.7%;and the order of organic matter rejection was sulfadiazine>carbamazepine>propranolol.（2）With the increase of the mass fraction of PEI,the NF membrane separation layer becomed thicker,the membrane Zeta potential becomed higher,the water flux decreased,and the salt rejection rate increased.Compared with the membrane without PEI,the water flux of NF membrane with 1.04 wt%PEI decreased by 28.3%,Na Cl rejection rate increased by17.6%,and Mg SO₄ rejection rate increased slightly;the rejection rate of trace organic matter increased,and the order of organic matter rejection size was propranolol>carbamazepine>sulfadiazine.（3）After the secondary interfaical polymerizated of PEI,the membrane pore becomed larger,the Zeta potential of the membrane increased,and the water flux becomed larger.Compared with the membrane without PEI in the secondary interfaical polymerization,the water flux of NF membrane with 1.04 wt%PEI increased by 1.78 times,the Na Cl rejection rate increased by 9.52%,and the Mg SO₄ rejection rate was increased by 17.2%;the rejection rate of trace organics increased,and the order of organic matter rejection was propranolol>carbamazepine>sulfadiazine.