Study On Blending Modified Polyethersulfone Membrane With Different Functional Nanomaterials And Its Ultrafiltration Performance

Polyethersulfone?PES?is a kind of polymer material with excellent comprehensive properties.It is one of the most widely used water treatment membrane materials because of its good thermal stability,chemical stability,acid and alkaline resistance,easy membrane formation and excellent mechanical properties.However,PES membrane still has problems during the separation process.On one hand,strong hydrophobicity of PES will result in a low water flux of the membrane during the filtration process;on the other hand,PES membrane has poor anti-fouling performance and are easy to adsorb organic pollutants such as proteins.During the filtration process,it is easy to be polluted by proteins and other organic substances in the water,resulting in the membrane pore being blocked and the water flux seriously decreasing.How to improve the water flux and anti-fouling performance of PES membranes is a research hotspot in the field of membrane separation.Permeability and selective separation are two important parameters for evaluating membrane separation performance.T herefore,Functional modification of PES membrane to improve the separation performance of membrane is very important.In this thesis,PES is used as the membrane matrix material,different functionalized nanomateri als are prepared as additives,and modified membranes are prepared by immersion precipitation phase transformation?NIPS?.The main research contents are as follows:?i?Water-soluble metal-organic framework?MOF?nanoparticles are fabricated and used as functional additives for modification PES to form a uniform porous membrane.During membrane formation,water-soluble MOF nanoparticles can be removed by dissolution in water,and a uniform porous structure is formed on the modified membrane.The effects of MOF size and the amount of MOF added on the micro-morphology,water permeability,anti-fouling ability and separation performance of the PES modified membrane are studied during the experiment,and the optimal ratio is obtained.When the mass fraction of MOF nanoparticle is 3%,the water flux of the modified membrane is up to 121.5 L m^-2 h^-1,and has a high rejection close to 100%for bovine serum albumin.?ii?Single-walled carbon nanotubes grafted with polysaccharides as functional additives are blended with PES to form membranes.Functionalized carbon nanotubes with different hydrophilicity are prepared by changing the mass ratio of polysaccharide to single-walled carbon nanotubes,and the effects of different functionalized single-walled carbon nanotubes on the separation performance of modified membranes are investigated.The effect of the amount of functionalized single-walled carbon nanotubes on membrane properties is further investigated.when the content of additive is 3 wt%.The modified membrane shows high pure water flux of up to 223.3 L m^-22 h^-1,and high rejection ratio for bovine serum albumin,and congo red of 98.5 and 98.8%,respectively.?iii?A polysaccharide-functionalized gold nanoparticle?DexDTM-AuNP?is synthesized by a one-step reduction method using NaBH₄ and blended with PES as an additive to form a membrane.The performance of the membrane is studied by changing the amount of polysaccharide-functionalized gold nanoparticles.Studies show that polysaccharide-functionalized gold nanoparticles effectively improve the hydrophilicity,antifouling and separation performance of the membrane.When th e content of DexDTM-AuNP is 3 wt%,the modified membrane shows high pure water flux of up to 134.5 L m^-2 h^-1,and the rejection ratio for bovine serum albumin,congo red,and methyl blue are 98.8,99.3,and 93.6%,respectively.?iv?The thermo-responsive polymer nanogel?DexPNI?is fabricated by RAFT polymerization and used as functional additives for modification of PES membrane.Three thermo-responsive polymer nanogels with different hydrophilicity are prepared by changing the mass ratio of polysaccharide to n-isopropyl acrylamide.The thermal response behavior of different hydrophilic nanogels and modified membranes is studied during the experiment.The effects of the content of additives on the hydrophilicity,permeability and separation performance of the PES modified membrane are further studied,and the optimal ratio was obtained.The obtained results show that the modified membrane has excellent hydrophilicity and rejection properties.Moreover,the pore size of the modified membrane can be adjusted for molecular separation by simply controlling the extension and contraction of the thermally responsive polymer chains.