Plasma/adsorbent system for NOx treatment in diesel exhaust: a case study on solid industrial wastes

For the past 2decades, electrical discharge-based non-thermal plasma is being utilized for the treatment of oxides of nitrogen and other hazardous air pollutants at the laboratory level. The discharge plasma exposure mainly results in oxidation of the gaseous pollutants necessitating usage of additional adsorbent/catalytic treatment. In this paper, the possibility of using the solid wastes from industries as a potential adsorbent for reducing oxides of nitrogen from diesel engine exhaust which is pre-treated with plasma discharges (direct plasma)/ozone mixing (indirect plasma) has been studied. Waste from agricultural industry (coffee husk), waste from marine industry (oyster shell), waste from metal casting industry (foundry sand), waste from aluminium extraction (red mud) and waste from thermal power plant (coal fly ash) have been used in this paper to study their gaseous pollutant adsorption capabilities. More than 90% reduction efficiency of oxides of nitrogen has been observed during the study. A comparative analysis of the industrial wastes has been made, and the synergistic effects have been discussed with respect to the plasma treatments. A new dimension to managing solid industrial wastes can be expected as a possible outcome of this work.