Preparation Of Carbon Dioxide Gsa Separation Membranes By A Molecule Self-assembly Method

TiO₂ nanoparticles,because of its excellent hydrophilicity and photocatalytic activity,have been widely used in thin film nanocomposite（TFN）membrane preparation to improve the membrane fouling and separation performance.However,the agglomeration of nanoparticles is a problem that must be faced in the preparation of TFN membrane doped with nanoparticles.Some researchers have improved the dispersion by modifying the surface of nanoparticles.However,this process is not only cumbersome,but also the loss of hydrophilicity.In this paper,tetra-butyl ortho-titanate（TBOT）was used instead of TiO₂ nanoparticles in the TMC oil phase.The solubility of TBOT in the oil phase is very good,and can be hydrolyzed to produce TiO₂ in the interfacial polymerization,which can improve the dispersion of titanium dioxide in the composite film,and effectively inhibit the occurrence of agglomeration.This method is more simple and effective,and easy industrialization.First of all,TFN membranes with the in situ formation of nano TiO₂ were prepared by interfacial polymerization.Interfacial reaction occurredbetween the aqueous phase of piperazine（PIP）and the organic phase of trimesoyl chloride（TMC）where tetrabutyl titanate（TBOT）was added before interfacial polymerization.The effect of TBOT addition on the properties and structure of the nanocomposite films was investigated by the analysis of in situ synthesized TiO₂.The interfacial polymerization process conditions were optimized.When the TFN nanofiltration membrane was prepared at the PIP concentration 2 g/L,the TMC concentration of 1 g/L,TBOT dosage of 250 mg /L,the heat treatment conditions of 80℃,and 10 min,the nanofiltration membrane performance was the best,and the rejection of Na2SO4 and NaCl were 95.3% and 54.1% respectively,and the pure water flux was 78 L/m²h（1 MPa,2000 ppm）.The characterization results showed that,when the amount of TBOT was less,TiO₂ had a good dispersion in the TFN membrane and no obvious agglomeration.Then,two kinds of conventional TFN membranes were prepared by directly adding TiO₂ into the oil and water phase,respectively.The experimental results showed that the TFN membrane prepared by in-situ synthesis of TiO₂ had better separation performance.The NF membranes were characterized by X ray photoelectron spectroscopy（XPS）,atomic force microscopy（AFM）,scanning electron microscopy（SEM）and the static contact angle.The results showed that in-situ synthesized TiO₂ particles in the membrane had excellent dispersibility,and effectively suppress the occurrence of agglomeration.At the same time,with theincrease of the surface roughness and the hydrophilicity of membrane,the In-situ TFN membrane maintained a high retention rate while the flux was greatly improved.Finally,the TFN nanofiltration membrane was applied to dye desalination,and the performance of anti-fouling and stability was tested.