Synthesis Of Organic-Inorganic Hybrid Modifier And Preparation Of High Permeability Polyethersulfone Membrane

Polyethersulfone（PES）is a kind of engineering polymer material with high physical and mechanical strength,chemical resistance,heat resistance,as well as long-term use.However,polyethersulfone itself has strong hydrophobicity,which requires high operating pressure in the process of use and is very easy to be fouling.The ideal water treatment membrane needs high permeability,high selectivity,anti-fouling,and sufficient mechanical strength.The hydrophobicity of polyethersulfone limits its development,so it is necessary to modify polyethersulfone to prepare separation membrane with excellent comprehensive performance.In this paper,organic-inorganic hybrid modifiers with different properties are prepared for the modification of polyethersulfone membrane,and the modified polyethersulfone membrane with high performance is prepared by non solvent induced phase separation method:（i）In order to improve the permeability of polyethersulfone membrane,the organic-inorganic hybrid modifier metal organic framework（ZIF-67）is prepared.Using ZIF-67 as modifier,the ultra-thin and dense polyethersulfone membrane is prepared by the movement and dissolution of ZIF-67 in the process of phase transformation.When ZIF-67 dissolves into water,the large number of sponges like pores will be formed,at the same time,the addition of ZIF-67 will improve the hydrophilicity,and the mutual diffusion rate between solvent and non-solvent will also increase,eventually leading to the thinning of dense layer and the increase of sponge pores.Therefore,with the increase of ZIF-67 content,the thickness of the dense layer of ZIF-67 modified polyethersulfone membrane is decreasing,and the thickness decreases to 123 nm.The modified membrane can obtain the maximum permeability with the minimum transport resistance.ZIF-67 modified polyethersulfone membrane has good permeability and separation performance.When the content of ZIF-67 was 4wt.%,the water flux of ZIF-67 modified polyethersulfone membrane is 55.696 L m^-2h^-1,and the high rejection ratio of bovine serum albumin（BSA）and congo red（CR）are 98%and 97%,respectively.（ii）In order to improve the permeability and anti-fouling of polyethersulfone membrane,the organic-inorganic hybrid modifier CNT-g-PAMPS is prepared by SI-e ATRP method.The anionic anti-fouling polyethersulfone modified membrane is prepared by phase inversion method.When the CNT-g-PAMPS are blended to modify polyethersulfone,the surface hydrophilicity of the modified membrane is improved,which could improve the permeability of the membrane.At the same time,it has negative charge and electrostatic repulsion with fouling in water,which improves the anti-fouling performance.When the mass of CNT-g-PAMPS in the casting solution is20 mg,the water flux can reach 365.5 L m^-2 h^-1,and the rejection ratio of BSA and CR is close to 100%.The flux recovery ratio and anti-fouling effect are also very significant.（iii）In order to improve the permeability,selectivity,anti-fouling,and extended service life of polyethersulfone membrane,the organic-inorganic hybrid modifier 3D network structure is prepared by electrostatic self-assembly method,and the conductive ultrafiltration membrane with 3D network structure and dense layer is designed to form a double-layer rejection area.And the pseudocapacitance characteristics of PANI could be used as the in-situ monitoring of fouling.The unique3D network structure and dense layer of polyethersulfone membrane have molecular transport channels,double-layer interception region and rigid hybrid structure,which effectively improve the small molecule flux,polymer rejection and cycle stability of the membrane.When the pressure is 0 MPa,the water flux of the modified membrane is 200.3 L m^-2 h^-1.With the increase of pressure,the water flux reaches 1 037.8 L m^-2h^-1 at 0.35 MPa,and the rejection ratio of the modified membrane is more than 99.9%.At the same time,the modified membrane has a long service life.