Preparation Of Microporous Polyarylate Thin-layer Composite Membrane And Its Nanofiltration Performance In Organic Solvents

Organic solvent nanofiltration（OSN）technology has shown great application potential in petrochemical,food and pharmaceutical fields due to its low energy consumption,high separation efficiency,and no phase change during the separation process.Thin-film composite（TFC）membrane is currently the most promising organic solvent nanofiltration membrane used for practical applications due to its excellent perm-selectivity and convenient scale-up production.The structure of the membrane determines the separation performance of the membrane,and the molecular structure of the monomer is an important factor affecting the microporous structure and separation performance of the TFC membrane.In this paper,TFC OSN membranes with twisted structure and inherent 3D microporous structure are prepared by designing monomer molecules to control the microporous structure of the polymer.The major research focuses on the following:（1）Fabrication of TFC membrane with binapthol-based microporous polyarylate and investigation of its organic solvent nanofiltration performanceThe BINOL-based monomer 7,7’-dihydroxy-2,2’-binaphthol（7,7’-OH-BINOL）with a rigid and a rotatable highly kinked unit was synthesized and used as the sole aqueous monomer to react with trimesoyl chloride（TMC）via interfacial polymerization on the surface of a cross-linked polyimide（XP84）membrane for the fabrication of high-flux BINOL-based polyarylate（PAR-BINOL）membranes.Results show that the PAR-BINOL membrane has high solvent flux and small molecular weight cut-off(MWCO<420 g mol^-1),in which the permeance of acetone is as high as 28.7 L m^-2 h^-1 bar^-1,the rejection of tetracycline（TC）is as high as 98.2%.Both simulated and experimental results confirm that the PAR-BINOL membrane has a rigid-flexible microporous and exhibits very high microporosity（FFV is 21%）and a large surface area(229.4 m² g^-1).The PAR-BINOL membrane shows high solvent permeability in various solvents with different polarities,and has long-term stable separation performance in a variety of organic solvents.（2）Fabrication of TFC membrane with pillar[n]arene-based microporous polyarylate and investigation of its organic solvent nanofiltration performanceThe per-hydroxylated pillar[n]arene（P[n]A,n=5,6）with nano-scale 3D inner cavity columnar structure was synthesized and used as the sole aqueous monomer to react with TMC via interfacial polymerization on the surface of a cross-linked polyimide（XP84）membrane for the fabrication of highly selective pillar[n]arene-based thin-film composite（TFC-P[n]A）membrane.Results show that by adjusting the dimension of the P[n]A inner cavity,the performance of the TFC-P[n]A membrane can be tailored.The methanol flux of the TFC-P[6]A membrane is 8.1 L m^-2 h^-1 bar^-1,and the MWCO is 300 g mol^-1.The hydrophobic 3D inner cavity in the TFC-P[n]A membranes can provide a channel for solvent penetration.Therefore,the TFC-P[n]A membrane shows high solvent permeability to various solvents with different polarities.Among them,the TFC-P[6]A membrane exhibits high hexane permeance of 1.7 L m^-2h^-1 bar^-1,which is two orders of magnitude higher than the TFC-PA membrane.From the perspective of the structure-properties relationship of membranes,in this work,the monomers with unique structures are synthesized for the fabrication of TFC OSN membranes having relatively high microporosity and tailorable 3D inner cavity,and thus high perm-selectivity.This work provides some insights for the design of materials to develop the next generation of organic solvent nanofiltration membranes.