Plasma cascaded solid wastes for possible adsorption of NO2 in diesel exhaust

Abstract

Extensive use of fossil fuel has led to an increase in solid and gaseous particulates in the environment, which in turn necessitated newer, effective, and economical control strategies to abate pollutants, particularly gaseous pollutants. In the current research work, focus has been placed on utilizing industry wastes to adsorb nitrogen oxides present in diesel engine exhaust, which is pre-treated by plasma. Sampled exhaust from a 5 kW diesel generator is exposed to discharge plasma where the oxidation of nitric oxide to nitrogen dioxide occurs, which is then made to flow through another reactor filled with industry wastes drawn from agriculture, foundry, utility, marine industry, etc., comprising mulberry waste, rice husk, wheat husk, areca nut husk, sugarcane bagasse, coffee husk, foundry sand, lignite ash, red mud, and oyster shells. While the adsorption of nitrogen dioxide was observed in all the wastes, reduction of nitric oxide was observed in metallic compound-based industry wastes. At about 184 J/L, specific energy plasma cascaded industrial waste red mud yielded 98% NO_x removal efficiency, and that with agriculture rice husk waste yielded 53% NOx removal. TiO₂/Fe₂O₃ present in industry wastes might have exhibited photo-catalysis in visible light resulting in the possible reduction of NO. A new pathway for recycling the waste can be expected through nitrogen dioxide adsorption, and the results are further discussed with respect to plasma-alone and cascaded plasma adsorbent systems.