Preparation And Performance Study Of Polypyrrole And Carbon Nanotube Modified Polyethersulfone Separation Membrane

Polyethersulfone(PES)as polymer is a common membrane separation material.It has broad application prospects in membrane separation process due to its excellent thermal stability,chemical resistance,and mechanical strength.However,the inherent hydrophobicity of the PES membrane is easy to cause membrane fouling.Therefore,modification of the membrane to enhance its anti-fouling performance is one of the focuses in the field of membrane technology in recent years.Polypyrrole(PPy)with good environmental stability is easily polymerized by chemical or electrochemical oxidation,which has a wide application prospect in the field of membrane technology.Carbon nanotubes(CNT)have become ideal nano fillers in polymer membrane materials due to their high specific surface area,mechanical strength,conductivity and excellent water transport properties.In this paper,PPy combined with CNT modified PES membranes were prepared and their preparation methods,modified microstructures and anti-fouling performances were systematically studied.In-situ chemical polymerization was used to prepare polypyrrole-carbon nanotubes composite material(PPy-CNT),and then PPy-C.NT/PES mixed matrix membranes were successfully prepared by the immersion phase inversion method.The porosity,permeability,mechanical properties and anti-fouling properties of PPy-CNT/PES mixed matrix membranes were systematically characterized.The results show that PPy-CNT/PES mixed matrix membranes have larger finger-like pore structure,higher porosity and average pore size than pristine PES membranes.The highest pure water flux of PPy-CNT/PES mixed matrix membranes can reach 261.67 L·m-2·h-1,which is about 2.6 times higher than that of pristine PES membrane.Their bovine serum albumin(BSA)rejection rates were greater than 95%.Meanwhile,the mechanical and anti-fouling properties of the mixed matrix:membranes were also improved.A simple vacuum filtration method was used to deposit CNT layer on the pristine PES membrane,and then synthesized PPy layer on the CNT/PES composite membrane through the two-step situ polymerization.Thus,the PPy/CNT/PES conductive composite membrane was successfully prepared.The permeability,conductivity,hydrophilicity and anti-fouling performances of the PPy/CNT/PES conductive composite membrane were systematically characterized.The results showed that the introduction of high conductivity PPy/CNT conductive layer improveds the conductivity of the composite membrane,and the electric resistance of the PPy-CNT/PES membrane was as low as 450±40 Ω·cm-1.Moreover,the PPy/CNT conductive layer has little effect on the permeability of the membranes,and its permeability is similar to that of pristine PES membrane.The anti-fouling tests for the PPy-CNT/PES membranes demonstrated that the FRR of the PPy-CNT/PES membrane was increased from 68.18%to 76.38%compared with the pristine PES membrane.The FRR was increased to 81.78%under the applied 1 V/cm electric field with the PPy-CNT/PES membrane as a cathode,which was about 20%higher than that of the pristine PES membrane.The above results demonstrate that the PPy-CNT/PES conductive composite membrane has significant potential for anti-fouling applications.