High-efficiency carbon-coated steel wool filter for controlling cooking-induced oil smoke

Cooking oil smoke (COS) contains many harmful substances, such as particulate matter, formaldehyde, and phenyl esters. Currently, commercial COS treatment equipment is expensive and requires a large space. Furthermore, a large amount of agricultural waste is generated and is mainly burned onsite, producing large amounts of greenhouse gases and air pollutants. This waste could be reused as a precursor for biochar and activated carbon. Therefore, this research used saccharification and catalytic hydrothermal carbonization to process rice straw and produce compact carbon-based filters (steel wool-C) for removing cooking-induced pollutants. Scanning electron microscopy indicated that carbon layers were coated on the steel wool. The Brunauer-Emmett-Teller surface area of the carbon filter was 71.595 m²/g, 43 times larger than that of steel wool. The steel wool filter removed 28.9%–45.4% of submicron aerosol particles. Adding a negative air ionizer (NAI) to the filter system enhanced the particle removal efficiency by 10%–25%. The removal efficiency of total volatile organic compounds was 27.3%–37.1% with the steel wool filter, but 57.2%–74.2% with the carbon-containing steel wool filter, and the NAI improved the removal efficiency by approximately 1%–5%. The aldehyde removal efficiency of the carbon filter with NAI was 59.0%–72.0%. Conclusively, the compact steel wool-C and NAI device could be promising COS treatment equipment for households and small eateries.