A.F. Zapata-Gonzalez, L.M. Valencia-Osorio, M.L. Álvarez-Láinez
Keywords: ceramic nanofibers, filtration, high temperature
Summary:One of the major challenges at large cities around the world is related to the air quality, in which atmospheric particulate matter (PM) has been a topic of great interest due to problems it causes in human health. PM is classified according its aerodynamic particle size (Φ), where PM10-2.5 (2.5 μm < Φ < 10 μm), PM2,5 (Φ < 2,5 μm), and PM0.1 (Φ < 0.1 μm) are the coarse, fine and ultrafine fractions, respectively. PM lower than 2,5 μm generate major health problems, because of the small size and large surface area they are difficult to remove by conventional cleaning or filtration systems. Likewise, they are easily breathable with a high deposition in the alveolar region or a different parts of the respiratory system, increasing the possibility to be transported to the blood . There are several factors which increase air pollution by particulate matter, one of them are vehicles combustion process and gases emitted from furnaces in some industry process, p.e. blast furnaces. One solution to control PM emission is filtration, in vehicles there are DPF or particulate filter system made of porous ceramics, but in industrial filtration process they need to cool the gas stream using heat exchanger or diluting the stream before the filtration process, in this case is normal to find bag filters which are made of polymers. Porous ceramic filters used in exhaust are a rigid structure that usually works approximately at 400°C and bag filters works at temperatures lower than 100°C. Currently, nanofiber based filters are gaining relevance due to the benefits they provide, such as high filtration efficiencies and low pressure drops, thanks to the effect of the size of the fibers (less than 500 nanometers). However, the development of nanofiber-based filters for high-temperature applications are still a challenge, because nanofibers as a filter membrane are mainly using polymer materials . We design a flexible ceramic filter with outstanding filtration performance for high temperature applications. This system combines the high thermal stability and the chemical stability against gases with the nanometric fiber size benefits (an average diameter of 194 ± 34 nm) achieving filtration capacity even at 1000°C without expensive pretreatments for hot waste gases. Pressure drop (ΔP) at 400 °C was evaluated at different air flow rate (1.0, 1.5 and 1.8 L/min) through a self-developed device and our ceramic membrane was compare with a commercial HEPA filters and it was found that ΔP in ceramic membrane decrease up to 90%.