Zhou Runyu, Zhou Gaofeng, Liu Yiqing, Wang Shixiang, Fu Yongsheng
Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University Chengdu 611756 China
RSC Adv. 2022 May 9;12(22):13810-13819. doi: 10.1039/d2ra00821a. eCollection 2022 May 5.
In this study, cobalt doped graphitic carbon nitride (Co-CN) was prepared and applied as a catalyst to activate peracetic acid (PAA) for sulfamethoxazole (SMX) degradation at neutral pH. PAA could be efficiently activated by Co-CN resulting in the efficient degradation of SMX. Characterization results of fresh and used Co-CN suggested that cobalt was successfully doped in graphitic carbon nitride (g-CN) through chemical bonding (Co-N bond) and the surface cobalt species in Co-CN (, [triple bond, length as m-dash]Co(ii) and [triple bond, length as m-dash]Co(iii)) were the main activators for PAA. Organic radicals (, CHC(O)O˙ and CHC(O)OO˙) were proved to be the dominant reactive species for SMX removal in the Co-CN/PAA system by radical scavenging experiments. The increase of cobalt doping content, PAA dosage or Co-CN dosage could accelerate SMX degradation and the neutral condition was highly favorable to SMX removal in Co-CN/PAA system. Co-CN exhibited a good stability and reusability for PAA activation in degrading SMX. Four possible degradation pathways of SMX (, hydroxylation, nitration, bond cleavage and coupling reaction) were proposed in the Co-CN/PAA system according to eight identified transformation products.
在本研究中，制备了钴掺杂的石墨相氮化碳（Co-CN）并将其用作催化剂，以在中性pH值下活化过氧乙酸（PAA）来降解磺胺甲恶唑（SMX）。Co-CN能够有效活化PAA，从而实现SMX的高效降解。新鲜和使用过的Co-CN的表征结果表明，钴通过化学键合（Co-N键）成功掺杂在石墨相氮化碳（g-CN）中，并且Co-CN中的表面钴物种（[三键，长度为m破折号]Co(ii)和[三键，长度为m破折号]Co(iii)）是PAA的主要活化剂。通过自由基清除实验证明，有机自由基（[三键，长度为m破折号]CHC(O)O˙和[三键，长度为m破折号]CHC(O)OO˙）是Co-CN/PAA体系中去除SMX的主要活性物种。钴掺杂量、PAA用量或Co-CN用量的增加均可加速SMX的降解，并且中性条件对Co-CN/PAA体系中SMX的去除非常有利。Co-CN在降解SMX的PAA活化反应中表现出良好的稳定性和可重复使用性。根据八种已鉴定的转化产物，在Co-CN/PAA体系中提出了SMX的四种可能降解途径（[三键，长度为m破折号]羟基化、硝化、键断裂和偶联反应）。
