Preparation And Application Of Polyamide Nanofiltration Membrane Based On TRZ-POP Interlayer

Polyamide membranes are the most reported nanofiltration membrane materials due to their low energy consumption and high-efficiency separation,and are widely used in seawater desalination and dye removal.However,it is reported that the thickness of the polyamide membrane is relatively large,and the membrane thickness leads to a low membrane flux.In order to reduce the thickness of the polyamide membrane and improve the water flux,this project builds a TRZ-POP interlayer on the bottom membrane.The TRZ-POP interlayer can regulate the interfacial polymerization reaction to prepare an ultrathin PA/TRZ-POP polyamide membrane.Significantly increased water flux.First,the TRZ-POP material was synthesized by the hot solvent method,and a series of polyamide composite films with TRZ-POP as the intermediate layer were prepared with a piperazine（PIP）concentration of 0.5 wt%.When the deposition concentration of TRZ-POP was 0.4 wt%,an ultrathin polyamide layer with a thickness of 60 nm was prepared,the thickness of the pure PA membrane was 180 nm,and the water flux of the PA/TRZ-POP-0.4membrane was 22 L m^-2h^-1bar^-1,which is 2 times that of pure PA membrane,and the rejection rate of Na₂SO₄is 93%.Secondly,in order to improve the water flux of the polyamide membrane and maintain the dye rejection rate.the PIP monomer concentration was reduced to 0.05 wt%.When the deposition concentration of TRZ-POP was 0.3wt%,an ultrathin polyamide（PA）layer less than 15 nm was formed on the TRZ-POP interlayer,which effectively reduced the mass transfer resistance of water.The ultrathin PA layer effectively reduces the mass transfer resistance of water and achieves a high water flux of 141.4 L m^-2h^-1bar^-1,maintaining the rejection to dyes at the expense of salt rejection.The high rejection rate of congo red,chrome black T and methyl blue is greater than 95%.Finally,in order to expand the practical application of polyamide membrane,polyamide nanofiltration membrane was used to treat sweet potato wastewater.The treatment effect on sweet potato wastewater was explored.When the PIP concentration is 0.5 wt%and the TRZ-POP concentration is 0.4wt%,the polyamide membrane reduces the COD value of the ultrafiltrate from14496 mg/L to 2218 mg/L,and the removal rate of impurities is 84.7%,which is better than Commercial NF7 polyamide membrane.