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.