Study On The Performances Of TETA-CS-PSf Composite Membrane For Carbon Dioxide And Nitrogen Separation

Compared with other separation processes membranes have advantages of high selectivity, low energy consumption, small footprint, simple manipulation, none pollution, easy to integrate with other technique. For CO2is the main greenhouse gas, in addition, the existence of carbon dioxide in natural gas and methane will reduce the combustion heat value and corrode pipes in the process of transportation, the separation of carbon dioxide will has a large market and bright future.Nowadays, the separation of carbon dioxide in membrane processes is a research hotspot. PSf showed excellent mechanical property:good abrasion resistance, high temperature resistant, high strength, better than other dissoluble engineering plastics. A kind of hollow fiber composite membrane for carbon dioxide and nitrogen separation has been prepared by using PSf as the membrane material, a chitosan as gutter layer and TETA as the coating material.First, the structure and performance of the PSf hollow fiber membranes prepared by solution spinning method (dry-wet spinning) has been systemically researched. The influences of the concentration of PSf, air gap of the dry-wet spinning process, the theta-composition of NMP/EtOH mixture and the concentration of PEG to the structure and performance of membranes were studied. The structure research and character analysis are made with SEM, gas permeability and separation coefficient. Summary from research, the preparation technology of membranes with high compressive strength and permeation is got. Second, with the dip-coating method,the hollow fiber composite membrane has been prepared using chitosan as the coating material. The influences of chitosan’s contents, coating times, operating temperature and pressure on the permselectivity of the hollow fiber composite membranes were investigated. It was found that the permeability of CO2and N2increased with the increase of operating temperature, which obeyed Arrhenius relation, and, the transport of N2through CS/PSf composite membrane followed solution-diffusion mechanism, while for CO2, its permeation performance was suggested to be effected by two aspects-solution-diffusion and facilitated transport. Summary from research, the method of coating is found. When the mass fraction of chitosan was0.5%, the coating time was1min, the permeation of CO2was16GPU, and the selectivity of CO2and N2was25.Finally, a TETA/CS/PSf hollow fiber composite membrane was prepared by coating TETA on the CS/PSf composite membrane. The influence of parameters including TETA’s concentration, coating times on the permselectivity of the composite membranes were investigated. When the mass fraction of TETA was2%, the coating time was5min, the permeation of CO2was19.8GPU, and the selectivity of CO2and N2was48, which was better than CS/PSf s.Besides, The resistance model of PSf substrate and composite membrane were established.