Preparation Of PTFE Hollow Fiber Membrane Filled With Carbon Nanotubes And Its Oil Water Separation Performance

Hollow fiber membrane has the advantages of high filling density,simple preparation process and equipment,and has become an attractive form of membrane separation module.The hollow fiber membrane based on polytetrafluoroethylene(PTFE)has the advantages of excellent acid and alkali resistance,high and low temperature resistance and high mechanical strength.At present,it is widely used in industrial wastewater and domestic sewage treatment,seawater desalination,oil-water separation,air purification and other fields.In this paper,the preparation process of PTFE hollow fiber membrane was studied,and the existing drawing sintering device was improved.The influence of drawing and sintering process parameters on the structure and performance of PTFE hollow fiber membrane was discussed.At the same time,a new method of filling PTFE hollow fiber membrane with carbon nanotubes was proposed to further improve its oil-water separation performance.(1)The PTFE hollow fiber membrane was prepared by the paste push pull sintering method,and the process and principle of the preparation process were studied.The existing drawing sintering device is improved by adding a group of lifting device.By controlling the up and down movement of the drawing roller,when the PTFE hollow fiber membrane breaks or needs to be reconnected,the joint of the PTFE hollow fiber membrane can be realized without opening the furnace door.The purpose of energy saving and continuous production is achieved,and the stability of the PTFE hollow fiber membrane product is effectively improved.(2)The stretching process and sintering process in the preparation process of PTFE hollow fiber membrane were explored.The effects of four process parameters,stretching temperature,stretching ratio,sintering temperature and sintering time,on the structure and properties of PTFE hollow fiber membrane were mainly discussed.The results show that the average pore size,porosity and water flux of PTFE hollow fiber membrane increase with the increase of drawing temperature and drawing ratio,while the bubble point pressure,breaking strength and elongation at break decrease;The tensile temperature has no significant effect on the physical size and surface wettability of the films.The larger the draw ratio,the smaller the physical size of PTFE hollow fiber membrane and the better the surface hydrophobicity.With the increase of sintering temperature and sintering time,the breaking strength of PTFE hollow fiber membrane increased and the elongation at break decreased;with the increase of sintering temperature and sintering time,the average pore size,porosity and water flux first increase and then decrease,and the bubble point pressure first decrease and then increase.The results show that the physical size and surface wettability of the films do not change significantly with sintering temperature and time.(3)In order to improve the oil-water separation performance of PTFE hollow fiber membrane,a modified method of PTFE hollow fiber membrane carbon nanotube filling method was proposed.And self-made modification device,the feasibility and modification mechanism of carbon nanotube filling modification scheme were explored.The results showed that the oil-water separation performance of PTFE hollow fiber membrane was significantly improved after filled with carbon nanotubes.Carbon nanotubes can fill the larger pores in PTFE hollow fiber membrane,which is conducive to achieve the effect of pore size uniformity.At the same time,carbon nanotubes can play the role of demulsification and further improve the oil-water separation performance of PTFE hollow fiber membrane.(4)The orthogonal experiment was set up to test the oil-water separation performance of PTFE hollow fiber membrane filled with carbon nanotubes by selecting three factors:the stretching ratio of PTFE hollow fiber membrane,the flow rate of peristaltic pump and the working time of peristaltic pump.The optimal process parameters of PTFE hollow fiber membrane modification were explored,and its oil-water separation performance was further explored.The influence of modification factors on the oil-water separation performance of carbon nanotube modified PTFE hollow fiber membrane was clarified,which laid a foundation for the development of high performance PTFE hollow fiber oilwater separation membrane.