The Preparation Of Nanofiber Membrane And Its Application In The Separation Of Trace Water From Liquid Oil And The Application Of Gas Phase High Temperature Industrial PM2.5 Filtration

Nanofiber membranes with a high specific surface area,high porosity and small pore size structure exhibit outstanding performance advantages over traditional fibrous filters in liquid&gas phase filtration,thus attracting tremendous attention of academia and industry.The Research&Development of nanofiber membranes have already spread in various countries and regions around the world,that has formed a certain market size.According to the industrial market reports,the global nanofiber market in 2017 was 1.236 billion US dollars,and would keep expanding with a 25.0%Compound Annual Growth Rate(CAGR)in the next few years.With the commercial development of industrial electrospinning equipment,nanofiber membranes will further expand the development of the global fiber filtration market section,and are also expected to gradually occupy a higher market share.The thesis topic take filtration in in two different meida of liquid&gas phase as application examples,respectively.One is the removal of trace water from oil and the other is the filtration of PM2.5 at the source of high-temperature industrial pollution.Which are aiming to improve the work efficiency of internal combustion engines as well as the treatment of global air pollution disaster,providing practical market application prospects.Trace water is inevitably presented in the fuel system due to lax management instorage and transport,which leads to a series of problems such as reduction of fuel combustion performance,corrosion of crucial metal parts and the growth of microorganisms,etc.In the first part of this thesis,the polyacrylic acid/polyvinyl alcohol(PAA/PVA)nanofibrous membrane was prepared by electrospinning under a high-voltage electric field.By optimizing the polymer composite ratio,the temperature and the reaction span of the thermal crosslinking,nanofiber xerogel membrane for removing the trace water from oil was obtained.The PAA/PVA nanofibrous xerogel membrane crosslinked at 160? for 30 min presents 124.8 times of swelling ration over its weight in deionized water,the absorption equilibrium can be obtained within 30 min and the nanofibrous hydrogel has robust mechanical strength.The nanofibrous xerogel membrane has an average pore size of 523.2 nm,a porosity of 79.6%and a tensile strength of 8.1 MPa.In addition,after the water-in-oil emulsion with a water content of 1 wt%was one-pass through the prepared PAA/PVA membrane,the originally milky emulsion became transparent with the water content for only 130 ppm.Different from the traditional water-in-oil separation mechanism,the trace water was maintained in the three-dimensional network of the nanofibrous hydrogel without a secondary separation process.This research provides an effective solution for the one-pass removal of trace water in fuel,which is beneficial to improve the performance of internal combustion engine machinery and reduce the frequency of mechanical failures.In order to address the terrifying influence of PM2.5 particulates in human health and environment aspects,we prepared polysulfonamide/polyacrylonitrile-boehmite(PSA/PAN-B)electret enhancement nanofibrous membrane to filtrate in industrial high temperature exhaust gas phases.By adding a small amount of polyacrylonitrile(PAN)as an auxiliary polymer,the spinnability of polysulfonamide(PSA)fibers is improved.The addition of inorganic boehmite nanoparticles not only enhances the mechanical strength of the fiber membrane,but also improves the specific surface area and thermal stability.By adjusting the content of inorganic boehmite nanoparticles and the basis weight of the fiber membrane,high efficiency and low-resistance PSA/PAN-0.5B nanofibrous membrane was obtained.As a result,the filtration efficiency of 1 g/m2 PSA/PAN-0.5B nanofibrous membrane is 99.52±0.32%while the pressure drop is only 45.16±1.39 Pa,showing the highest quality factor(QF value)of 0.119±0.008.Besides,the membrane can maintain its filtration efficiency and stability after different test wind speed,high temperature treatment as well as acid and alkali solution immersion.Furthermore,the smoke generated by the burning of sandalwood was applied to simulates the application prospect of the nanofiber membrane in real PM2.5 filtration.Combining with the SEM images under different filtration time,the capture mechanism of the oily pollution particles by the nanofiber membrane is proposed.This study provides an effective solution for the filtration and removal of PM2.5 from the high-temperature industrial pollutant sources,which is beneficial to alleviate the damage of air pollution to human health and further broadens the application range of PSA nanofibers.