Removal of aqueous oxytetracycline using copper-loaded biochar-activated peroxodisulfate: Synergistic mechanism of adsorption and nonradical 1O2
Qingzhu Zeng, Junfeng Zhu, Jiujiu Xiong, Wen Zha, Jiahui Liu, Xiangchu Zeng, Guanghua Zhang
Abstract
Antibiotic contamination from livestock and poultry farming wastewater has caused substantial adverse effects on the environment and humans. Therefore, in this study, bifunctional adsorption and synergistic degradation of Cu and N codoped biochar (Cu-N/BC) were utilized to efficiently promote the activation of peroxodisulfate (PDS) for removing oxytetracycline (OTC). Cu-N/BC exhibited a high adsorption affinity toward OTC. The adsorption of OTC (50 mg/L) by 0.4 g/L catalyst could reach 36.2 mg/g in 30 min, and the removal of OTC reached 97.24 % in 90 min after adding 0.5 mM PDS. Preadsorption experiments demonstrated that the OTC enriched on the Cu-N/BC surface facilitated the subsequent degradation reaction，its reaction rate constant increases from 0.026 to 0.037. Low-valent copper (Cu 0 /Cu + ), pyridine N, and oxygen-containing functional groups (C O) were the main active sites of Cu-N/BC, and the main contribution toward OTC degradation was from the nonradical pathway of singlet oxygen. Furthermore, potential degradation pathways were revealed, and the intermediates in the OTC degradation process were identified. Cu-N/BC exhibited stable performance, a wide pH application range, and great potential for practical application. This study offers a new concept for designing a bifunctional carbon-based material to remove antibiotics from wastewater.