Unleashing the power of cobalt pyroborate: superior performance in sulfate radical advanced oxidation processes

• Published in: Environmental science. Nano 2024-11, Vol.11 (11), p.4621-4633
• Main Authors: Lin, En-Xuan, Wu, Fang-Yu, Zhu, Yu-Lun, Chang, Yu-Rong, Wu, Po-Yi, Keng, Pei Yuin
• Format: Article
• Language: English
• Subjects: Catalysts; Catalytic activity; Cobalt; Cobalt oxides; Degradation; Electron paramagnetic resonance; Electron spin resonance; Industrial wastes; Industrial wastewater; Industrial wastewater treatment; Nanoparticles; Nitrophenol; Organic matter; Oxidation; Oxygen; p-Nitrophenol; Persistent organic pollutants; Pollutants; Rate constants; Reactive oxygen species; Singlet oxygen; Sulfamethoxazole; Sulfates; Wastewater treatment; Water treatment
• ISSN: 2051-8153; 2051-8161
• DOI: 10.1039/d4en00516c

This study presents structurally robust cobalt pyroborate (Co 2 B 2 O 5 ) as a heterogeneous catalyst for advanced oxidation processes (AOPs). The Co 2 B 2 O 5 nanoparticles were systematically characterized and employed to activate peroxymonosulfate (PMS) effectively in the degradation of various organic recalcitrant pollutants. When compared to conventional heterogeneous CoO and Co 3 O 4 catalysts in sulfate radical-advanced oxidation processes (SR-AOPs), the Co 2 B 2 O 5 catalyst exhibited seven-fold and 2.7-fold increases in degradation rate, respectively. The Co 2 B 2 O 5 /PMS system was optimized to enable degradation of a diverse array of persistent organic pollutants, including tetracycline, 4-nitrophenol and sulfamethoxazole, with respective first-order rate constants of 0.136 min −1 and 0.104 min −1 , and 0.092 min −1 , respectively. Mechanistic insights, supported by selective trapping experiments and electron paramagnetic resonance (EPR) analyses, revealed that surface-bound sulfate radicals serve as the primary reactive oxygen species (ROS) under dark conditions. Singlet oxygen species also contributed to the degradation process via a non-radical pathway. Remarkably, the catalyst maintained its effectiveness in the presence of natural organic matter, highlighting its potential practical applicability for wastewater treatment. This study presents the single-component cobalt pyroborate catalyst with high catalytic activity under varying conditions, thus providing unprecedented benefits for industrial wastewater treatment applications. The Co 2 B 2 O 5 /PMS system demonstrates superior efficiency in degrading persistent organic pollutants, surpassing traditional CoO and Co 3 O 4 catalysts, making it a promising solution for industrial wastewater treatment.