| In recent years,semiconductor photocatalysis has shown great potential in the treatment of environmental pollution and the resolution of energy problems,whether it is in the progress of laboratory research or the photocatalysis of sewage treatment plants in the pilot phase.Among many photocatalysts,TiO2 is widely used due to its advantages of high efficiency,low cost,non-toxicity,sustainability,and ease of use.However,the high cost and complexity of recycling the used catalyst particles hindered the commercialization process.The combination of photocatalyst and membrane separation technology will effectively solve this problem,and is expected to achieve large-scale commercial application.In this paper,we did conductive modification,photocatalytic modification and hydrophilic modification on PVDF ultrafiltration membranes,and we did research on the physical,electrochemical,photocatalytic and membrane filtration performance of the membranes.The results of the research are listed below:1)Adding ACET to the PVDF membrane can form a conductive network in the membrane,thereby giving it a certain conductivity.Adding SDS can greatly improve the distribution of ACET in the membrane and increase the conductivity of the membrane by more than three times.The greater the proportion of ACET added,the better the connectivity of the conductive network in the membrane,and the stronger the conductivity of the membrane,but as the ratio increases,there are certain boundary effects,and excessive ACET will destroy the structure of the membrane itself,causing mechanical unstable performance,which affects its filtering performance.2)The addition of P25 has a certain degree of influence on the performance of the membrane.When the proportion of P25 is less than 1%,P25 will reduce the membrane impedance;when the proportion of P25 is greater than 1%,the membrane impedance will increase.The results of the chopping current test and the photocatalytic efficiency test remain the same,from low to high:0%P25<1%P25<3%P25<2%P25.2%P25 membrane can degrade 93%MB in 120 minutes.The individual test results show that the photocatalysis is higher than the sum of the efficiency of the electrocatalysis and the photocatalysis alone,which reflects the synergy of the photocatalysis.In photocatalytic membrane filtration and degradation of MB,the rate of membrane flux decline is consistent with the photocatalytic efficiency,that is,the 2%P25 membrane with the highest photocatalytic efficiency has the best anti-pollution performance,and its mechanical stability is also the best,which maintain a high purification rate of 87%.3)PVDF membrane prepared by TNB instead of P25 has lower impedance,higher chopping current response and higher photocatalytic efficiency.PVDF membranes prepared by PTFE instead of PVP have lower hydrophilicity,higher impedance,lower chopping current response,and lower photocatalytic efficiency.In the photocatalytic membrane filtration test,the initial purification rate of the membrane with TNB was higher than that of the membrane with P25,but the purification rate decreased faster,and the membrane with P25 was more stable.Membrane with PTFE membrane is not as persistent as membrane with PVP,and the purification rate decreases more obviously after a period of time,which indicates that its membrane flux is low,it is easy to block,and the mechanical structure is more easily damaged.PVDF ultrafiltration membrane using PVP+P25 currently has the best water treatment efficiency and material stability,and membranes for other materials need to be improved. |
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