Comparative evaluation of plasma-assisted and photochemical advanced oxidation processes for p-nitrophenol degradation in water

Abstract

The present study examined the degradation of p-nitrophenol (PNP), a hazardous and long-lasting nitroaromatic contaminant commonly found in industrial wastewater, through a comparative analysis of various treatment methods utilizing CuO-Fe sub(2)O sub(3) mixed oxide catalysts. The effectiveness of adsorption, photocatalysis, photo-Fenton oxidation, catalytic ozonation, plasma treatment, and plasma-assisted catalytic oxidation was thoroughly evaluated under controlled settings. Among the evaluated catalysts, the C3 (CuFe sub(2)O sub(4)) catalyst exhibited the highest adsorption capacity and catalytic efficiency, facilitating the effective degradation of PNP via various advanced oxidation processes. Photocatalytic degradation under UV light resulted in significant PNP removal, whereas the UV-H sub(2)O sub(2)-catalyst system achieved nearly complete degradation (98-100 percent) within 10 min, owing to enhanced hydroxyl radical (.OH) generation via combined photolytic and catalytic processes. Catalytic ozonation further boosted degradation efficiency by facilitating the surface-mediated decomposition of ozone (O sub(3)) into reactive oxygen species. Plasma treatment produced several oxidizing agents, including O sub(3), nitrite (NO sub(2-), nitrate (NO sub(3)-), hydrogen peroxide (H sub(2)O sub(2)), and reactive radicals, which accelerated the oxidative degradation of PNP. This comparative assessment underscores the synergistic effect of catalyst-assisted radical generation in accelerating pollutant degradation and offers insights into selecting appropriate advanced oxidation methods for effectively treating nitroaromatic pollutants in water.