Electrospun fibrous aerogels for air filtration

• Main Author: Tng, Zi Kang
• Other Authors: Lu Xuehong
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Materials::Nanostructured materials
• Online Access: http://hdl.handle.net/10356/76739
• Institution: Nanyang Technological University

In the pursuit of economic growth and a higher standard of living, the increase in industrialization and urbanization of cities have inevitably led to an increasing rate of air pollution. There is a growing concern regarding air pollution due to its harmful effects on the human body. Studies have shown that prolonged exposure to particulate matter (PM2.5 , PM10) and fine particles (PM1, PM0.1) found in air pollution results in a higher chance of cardiopulmonary and lung disease and a higher mortality rate. Current measures to reduce air pollution include the use of porous membrane and fibrous air filters. However, these filters face limitations such as high pressure drop and a drop in filtration efficiency at high temperatures. To overcome these limitations, a novel Polyimide-Polyacrylonitrile/ZIF-8 nanofibrous aerogel (NFA) filter was developed in this study. The aerogel filters were prepared by unidirectional freezing of homogenized suspension of PI and PAN/ZIF-8 fibers. The ice crystals in the frozen aerogels were subsequently removed by sublimation during the freeze-drying process, which was then followed by a thermal imidisation treatment up to 300 ºC. The highest filtration efficiency of 99.86% at a low pressure drop of 50 Pa-1 was recorded for the NFA (5:5) filter, for the particle size of PM1 at a wind speed of 0.05m/s. The NFA filters displayed high thermal stability and minimal weight loss at 300 ºC during Thermogravimetric analysis. A compression test of 100th cycles of the NFA filter showed that the filters retained their mechanical integrity as seen from the cyclic stress-strain curves. These findings show that the PI-PAN/ZIF-8 NFA filters can potentially be used in the filtration of fine particles at high temperature environment, such as car exhaust and coal furnace exhaust where the temperatures can range up to 300 ºC.