封装型双金属阴极催化剂强化电芬顿技术高效去除磺胺甲恶唑

Highly efficient removal of sulfamethoxazole by encapsulated bimetallic cathode catalyst enhanced electro-Fenton technology

传统非均相电芬顿(EF)技术主要面临活性氧物种生成速率慢、催化剂稳定性差等不足。将FeCo-ZIF和三聚氰胺(MA)共混(质量比为1:100)煅烧,成功制备出氮掺杂碳纳米管封装铁钴合金阴极催化剂(NCNT@FeCo),可强化EF高效去除水中磺胺甲恶唑(SMZ,初始质量浓度为20 mg·L^(-1)),在近中性条件下50 min内即可完全去除,降解速率常数可达0.057 min,是单独煅烧FeCo-ZIF制备的裸露型双金属催化剂FeCo-N的3倍,且前者的金属浸出总量(0.27 mg·L^(-1))仅为后者(1.79 mg·L^(-1))的15.1%。循环回用5次后,60 min内NCNT@FeCo对SMZ的去除率仍可达到96.0%。扫描电子显微镜表征与电化学阻抗测试结果表明,由MA诱导生成的N-CNT,不仅通过封装结构有效限制了内部铁钴合金受强氧化性环境腐蚀破坏,而且显著加速了内部铁钴合金的电子传递速率,N-CNT@FeCo的独特封装结构使其兼具高催化活性和高稳定性。本研究为高效稳定的阴极催化剂提供了稳定、可控、易放大的封装策略。

The conventional non-homogeneous electro-Fenton(EF) technology mainly faces the deficiencies of slow generation rate of active oxygen species and poor catalyst stability. A nitrogen-doped carbon nanotubeencapsulated iron-cobalt alloy cathode catalyst(N-CNT@FeCo) was successfully prepared by calcination of FeCo-ZIF and melamine(MA) in a co-blend with mass ratio of 1:100, which could enhance EF to efficiently remove sulfamethoxazole(SMZ, initial concentration set as 20 mg·L^(-1)) from water, and SMZ could be completely removed within 50 min under near-neutral conditions with degradation. The degradation rate constant was up to 0.057 min, which was two times higher than that of the bare bimetallic catalyst FeCo-N prepared by calcination of FeCo-ZIF alone, and the total metal leaching from the former(0.27 mg·L^(-1)) was only15.1% of that from the latter(1.79 mg·L^(-1)). 96.0% of SMZ removal was still achieved at 60 min when NCNT@FeCo was recycled after five times. Scanning electron microscopy analysis and electrochemical impedance test results showed that the N-CNT induced by MA not only effectively limited the corrosion damage of the internal iron-cobalt alloy by the strong oxidizing environment through the encapsulation structure, but also significantly accelerated the electron transfer rate of the internal iron-cobalt alloy, and the unique encapsulation structure of N-CNT@FeCo made it both highly catalytic activity and highly stable. This study provides a stable,tunable and easy to enlarge encapsulation strategy for the preparation of efficient and stable cathode catalysts.