Cu@NCS催化剂催化臭氧降解甲基橙性能与机制研究

Study on the Performance and Mechanism of Cu@NCS Catalyst Catalyzed Ozonation for Methyl Orange Degradation

摘要: 印染废水中的偶氮染料结构稳定、难生物降解，催化臭氧氧化是实现其深度处理的有效途径。本研究采用自聚合-高温热解制备Cu负载氮掺杂碳纳米球(Cu@NCS)，并以偶氮染料甲基橙(MO)为目标污染物，系统探究了该催化剂在臭氧氧化体系中的催化性能与作用机制。表征结果显示，最优样品Cu@NCS-3呈规整球形，Cu⁰高度分散于碳骨架中，吡啶氮占比22%，缺陷密度(I_D/I_G = 1.23)适中，为催化活性提供了结构基础。催化剂投加量100 mg/L、pH为7.0、O₃浓度100 mg/L的条件下，60 min内对100 mg/L的MO去除率达94%，COD去除率75%，降解速率(0.0438 min⁻¹)为单独臭氧的2.8倍。自由基淬灭与EPR结果表明，该体系遵循•OH主导、$O_2^{•-}$ 为辅的氧化机制，Cu⁰促进O₃原位分解生成表面吸附活性氧(*O)、氮掺杂碳载体sp²杂化稳定Cu⁰颗粒促进Cu⁺/Cu²⁺氧化还原循环，生成•OH和$O_2^{•-}$ 活性物种。该工作为碳基金属催化剂设计及偶氮染料废水深度处理提供了理论与实验支撑。

Abstract: Azo dyes in printing and dyeing wastewater are structurally stable and difficult to be biodegraded. Catalytic ozonation is an effective way to achieve their advanced treatment. In this study, Cu-loaded nitrogen-doped carbon nanospheres (Cu@NCS) were prepared by self-polymerization and high-temperature pyrolysis. The catalytic performance and mechanism of the catalyst in ozonation system were systematically investigated with azo dye Methyl Orange (MO) as the target pollutant. The characterization results show that the optimal sample Cu@NCS-3 is regular spherical, Cu⁰ is highly dispersed in the carbon skeleton, pyridine nitrogen accounts for 22%, and the defect density (I_D/I_G = 1.23) is moderate, which provides a structural basis for catalytic activity. Under the conditions of catalyst dosage of 100 mg/L, pH of 7.0, and O₃ concentration of 100 mg/L, the MO removal rate of 100 mg/L reached 94% within 60 min, and the COD removal rate was 75%. The degradation rate (0.0438 min⁻¹) was 2.8 times that of ozone alone. The results of free radical quenching and EPR showed that the system followed the oxidation mechanism dominated by •OH and supplemented by $O_2^{•-}$ . Cu⁰ promoted the in-situ decomposition of O₃ to form surface-adsorbed reactive oxygen species (*O), and the sp² hybridization of nitrogen-doped carbon carrier stabilized Cu⁰ particles to promote the Cu⁺/Cu²⁺ redox cycle, generating •OH and $O_2^{•-}$ active species. This work provides theoretical and experimental support for the design of carbon-based metal catalysts and the advanced treatment of azo dye wastewater.