A cost-effective Fe-Cu-Cr oxide/activated-carbon catalyst for peroxymonosulfate-driven degradation of p-nitrophenol

p-Nitrophenol (p-NP) is a toxic and persistent pollutant commonly found in industrial wastewater, making the development of efficient and economically viable treatment technologies an urgent necessity. In this work, we develop a low-cost and high-performance catalyst consisting of Fe-Cu-Cr mixed metal oxides supported on activated carbon (AC), which was synthesized via an impregnation-calcination method and was applied for the activation of peroxymonosulfate (PMS) to degrade p-NP. Optimization of preparation parameters revealed that HCl pretreatment of activated carbon, a ternary Fe-Cu-Cr composition, a 20 wt% metal loading, and calcination at 600 °C yield the highest catalytic activity, achieving p-NP degradation up to 75% after 4 hours. While maintaining a high p-NP degradation efficiency, our work presents a cost-effective catalyst with a total treatment cost below 30 CNY per ton, which is over 40% lower than previous reported studies. Mechanistic studies show that p-NP degradation follows a synergistic adsorption-catalysis pathway, wherein activated carbon enriches p-NP at the catalyst surface and multivalent metal oxides efficiently activate PMS to generate reactive oxygen species, primarily ˙OH. This work introduces a practical, scalable, and cost-effective catalyst design using earth-abundant metals, thus providing a promising technical approach for the remediation of recalcitrant organic pollutants in industrial wastewater.