Preparation And Interception Performance Of GO Combined With TiO₂ Modified PVDF Ultrafiltration Membrane

Polyvinylidene fluoride?PVDF?is one of the most popular membrane materials due to its chemical stability,high mechanical strength and anti-aging.However,because PVDF pollution resistance is relatively poor,resulting in increased the costs of membrane operation and membrane life shortened and so on.In this paper,PVDF hollow fiber ultrafiltration membrane?referred to the original membrane?was modified by using a highly hydrophilic graphene?GO?and titania?TiO₂?as modifier,and using the modification method of conbining suction adsorption with interface polymerization.Last,the optimum preparation conditions of GO-TiO₂ modified hollow fiber ultrafiltration membrane?GO-TiO₂ modified membrane?were obtained.The retention properties of deltamethrin pesticide micro-polluted water in the coagulation-ultrafiltration process were investigated.The main research results are as follows:1.Through orthogonal experiments and continuous experiments,the optimum preparation conditions of GO-TiO₂ modified membrane were as follows: butyl titanate?TBOT?2mg;GO 1mg;m-phenylenediamine?MPD?1wt%;MPD soaking time 8min;1,3,5-benzotriyl chloride?TMC?0.2wt%;TMC soaking time 10 min.2.Comparative experiments of conbining different modifiers and modification processes showed that in terms of membrane anti-fouling performance and improved separation performance:?1?in the modified way: suction adsorption + interface polymerization>interface polymerization> suction adsorption;?2?on the choice of modifier: GO-TiO₂>GO> TiO₂.3.Anti-pollution performance and retention performance of GO-TiO₂ modified membrane had been greatly improved,the static adsorption capacity of humic acid?HA?decreased from 295.0 mg/m2 to 158.6 mg/m2,the interception rate of humic acid?HA?increased from 81.0% to 90.1%.4.GO-TiO₂ modified membrane has a high degree of hydrophilic properties.Its surface hydrophilic functional layer is GO-polyamide-TiO₂ composite structure,the membranesurface is rich in a large number of-COOH,-OH and other hydrophilic groups,membrane surface O/C element quality ratio improved from 0.109 before 0.556,the water contact angle decreased from?80.6 ± 1.8?to?38.6 ± 1.2 °?.5.The flux attenuation of GO-TiO₂ modified membrane was greatly retarded,the total decay rate of flux decreased from 51.2% before modification to 35.6%,irreversible pollution to reversible pollution conversion,irreversible decay rate from 24.3% to 7.1%.6.GO-TiO₂ modified membrane filtration cycle is improved.When the flux is lost by30%,the filtration time of GO-TiO₂ modified membrane is prolonged from 240 min before modification to 570 min.7.Hydraulic backwashing can effectively improve the flux recovery rate of GO-TiO₂ modified membrane.After 5 times "filtration-cleaning" cycles,the flux recovery rate increased from 69% before modification to 94%.8.The deltamethrin micro-pollutants were taken as the research object,the removal efficiency of deltamethrin by GO-TiO₂ modified membrane in the direct coagulation,direct ultrafiltration and coagulation-ultrafiltration process was as follows: Coagulation-ultrafiltration> direct coagulation> direct ultrafiltration.Among them,the removal efficiency of Coagulation-ultrafiltration combined process that using GO-TiO₂ modified membrane was the best,and the removal rate was 83.7%.9.The excellent hydrophilicity of GO-TiO₂ modified membrane significantly retarded the rate of membrane fouling.After filtering the deltamethrin water sample for 300 min,the membrane flux loss rate of the original membrane was 39.8%,while the flux loss rate of GO-TiO₂ modified membrane decreased to 20.4%.In summary,the modified GO-TiO₂ modified membrane improved the anti-pollution performance,while its retention capacity for the deltamethrin pesticide micro-polluted water also has a greater degree of improvement.