Microstructure of PDA/PVDF ultrafiltration membranes under two pore-forming agents and comparison of their retention of organic dyes
In order to improve the pollution resistance of polyvinylidene fluoride(PVDF)ultrafil-tration membrane to organic dyes,PVDF modified ultrafiltration membrane(PDA/PVDF mem-brane)was prepared by phase transformation method using polydopamine(PDA)as modifier,polyvinylpyrrolidone(PVP)and lithium chloride(LiCl)as pore-forming agents,respectively.We studied the effects of PDA content on the microstructure,fracture strength,dye retention and pollution resistance of PDA/PVDF membrane prepared with two different pore-forming agents,and the permeation separation performance of PDA/PVDF membrane on neutral red,reactive brilliant orange K-NG and dispersed deep blue HGL.The results show that with the increase of PDA content,the pore structure of the membrane is improved,the average pore diameter of the PDA/PVDF membrane with PVP significantly increases,and the hydrophilicity of the membrane is significantly improved,and the contact Angle of the PDA/PVDF membrane with PVP decrea-ses by 24.6%.The addition of PDA can greatly improve the pure water flux and dye retention rate of the PDA/PVDF membrane.The pure water flux of the PDA/PVDF membrane using PVP as the pore-forming agent is much greater than that of the PDA/PVDF membrane using LiCl as the pore-forming agent.The PDA/PVDF membrane using LiCl as the pore-forming agent has the better retention effect on the three dyes.The retention rate of disperse deep blue HGL can reach 87.05%.The addition of PDA can improve the anti-pollution performance of the membranes to some extent.The two kinds of pore-forming agent PDA/PVDF membranes have higher flux re-covery rate for active orange K-NG.When the content of PDA is 1.6%,the flux recovery rate for active orange K-NG reaches 94.1%.
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