A New Approach in Reducing NOx in Diesel Exhaust by Discharge Plasma Catalytic Activity in Composite Industry Wastes

Hazardous gases such as oxides of nitrogen (NO x ) come from fossil fuel combustion and, therefore, require special attention because there is a regular usage of fuel on a day‐to‐day basis. In the current work, a new methodology is proposed for diesel exhaust treatment involving electrical discharge plasma causing possible catalysis in a combination of two industrial wastes (composite waste) for removal of NO x . A dual‐metal film and helical wire reactor were used to generate surface discharge plasma at room temperature and pressure. Five composite wastes (CW), namely, waste tiles + foundry sand, copper slag + red mud, iron tailings + waste tiles, red mud + waste tiles, and foundry sand + red mud, were used to examine their catalytic properties. A 5‐kW diesel engine exhaust was sampled for laboratory experiments. The NO x removal efficiency, which was 16% under plasma‐alone treatment at a specific energy of 140 J/L, got enhanced to 80%–93% in plasma‐catalysis mode when CWs containing metal oxides were introduced into the plasma reactor. Further, it was verified that plasma catalysis with individual wastes yielded less NO x removal efficiency compared to that with CWs (40%–71% against 80%–93%), indicating the synergy of two wastes that are blended in the CWs.