Preparation And Study On Performance Of TA/CS Composite Nanofiltration Membrane

Membrane technology is a water treatment technology that has attracted much attention in the 21st century.It is used in various fields of production and life,and nanofiltration technology is one of the technologies with a relatively wide range of applications and more products in membrane technology.As the core of nanofiltration technology,nanofiltration membrane has the advantages of low operating pressure and good separation performance.It is a popular research object in the field of membranes.The most commonly used method for the preparation of nanofiltration membranes is interfacial polymerization.In this study,the traditional polyacrylonitrile（PAN）ultrafiltration membrane was hydrolyzed and modified,and the prepared tannic acid（TA）/chitosan（CS）colloidal particle solution was used as the aqueous phase,and trimesoyl chloride（TMC）Dissolved in n-hexane as the oil phase,Using the coordination and chelation of Fe³⁺to promote the rapid co-deposition of TA/CS colloidal particles on the surface of the modified PAN ultrafiltration membrane,and then on its surface A TA/CS composite nanofiltration（NF）membrane was prepared by interfacial polymerization of acid chloride（TMC）.The filtration performance of TA/CS composite nanofiltration membrane was studied.In addition,the sulfonated amine monomer2,4-diaminobenzenesulfonic acid（MPDASA）was added to the water phase to study the filtration performance of the sulfonated composite membrane after the introduction of sulfonic acid groups.Taking polyacrylonitrile hydrolysis time,TA concentration,CS concentration,TMC concentration,interfacial polymerization time,heat treatment temperature and time as the main research objects,the effects of seven preparation conditions on the performance of TA/CS composite membranes were studied.In addition,for the sulfonated composite membrane,the influence of the concentration of the sulfonated amine monomer MPDASA on the filtration performance of the sulfonated TA/CS composite membrane was studied.The composite nanofiltration membrane was characterized by SEM,AFM,XPS,WCA,Zeta potential analysis and other means,the surface morphology and roughness,chemical properties,hydrophilicity and hydrophobicity and chargeability of the base membrane and composite membrane were analyzed.Researched and compared the filtration performance of different composite membranes.And studied the improvement of the antifouling effect of the sulfonated composite membrane.The final result is as follows:By adjusting and controlling the influencing factors of the membrane,it was found that when the concentrations of TA,CS,and TMC were 0.15%,0.25%,and0.1%,respectively,the interfacial polymerization time was 3min,the base membrane hydrolysis time was 1h,and the heat treatment was performed at 60℃for 10min.The prepared TA/CS composite membrane has the best performance.The rejection rates of Na₂SO₄,Mg SO₄and Na Cl were 95.15%,87.24%and 75.32%,respectively,and the pure water flux reached 26.97 L·m^-2h^-1（0.5Mpa,room temperature）.When concentration of sulfonated amine monomer MPDASA is 0.075%,the salt rejection rate of the sulfonated TA/CS composite membrane is the best,and the rejection rate of Na₂SO₄and Mg SO₄reaches 96.21%and 90.35%,respectively.SEM and AFM proved the formation of a dense surface layer of the composite membrane.XPS proved the existence of Fe³⁺and sulfonic acid groups,and proved that the interfacial polymerization reaction occurred.The results of the filtration performance test of different composite membranes show that the performance of HPAN-1,HPAN-2 and HPAN-3 is quite different,and the salt rejection capacity of HPAN-1 is much lower than the latter two membranes,which proves that under the condition of Fe³⁺,Which greatly improves the salt rejection performance of the composite membrane.And the sulfonated composite membrane HPAN-3 has better antifouling performance.It has excellent flux recovery rate（FRR）after filtering for24h under 0.1g/L humic acid（HA）and bovine serum albumin（BSA）.The flux recovery rate in BSA is 87.07%,and the recovery rate in HA reaches 94.45%.