Abstract:

Carbon-based catalysts with heteroatom doping and porous structures are desired for advanced oxidation processes (AOPs). Herein, Co and Cu co-doped porous carbon were developed by using metal-organic frameworks-74 (MOF-74) as self-sacrificial template and performing subsequent carbonization. The obtained samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), et al. The optimal composite catalyst (Cu₁Co₁-OC) exhibited excellent catalytic degradation performance toward 4-nitrophenol (4-NP). More than 98% of 4-NP (60 mg·L^-1) could be removed within 15 min by 100 mg·L^-1 of catalyst and 2 g·L^-1 of peroxymonosulfate (PMS) at pH=6. Moreover, the catalyst showed good stability and reusability with about only 10% efficiency loss after 4 cycles. The effects of catalyst and PMS dose, pollutant concentration, pH and common anions were investigated, and reactive oxygen species (ROS) were studied by scavenger experiments and electron paramagnetic resonance (EPR) tests. Quenching experiments and electron paramagnetic resonance analysis showed that both free radicals (·SO{}_{\mathrm{4}}^{-}, ·OH, ·O{}_{\mathrm{2}}^{-}) and non-free radicals (¹O₂) participated in the degradation reaction. During the reaction process, the redox cycle of Co²⁺/Co³⁺ and Cu⁺/Cu²⁺ effectively activated PMS and promoted the generation of active oxide species, thereby improving the performance of the catalyst for the degradation of nitrophenols.

Key words: oxidation, catalyst, waste water, peroxymonosulfate, 4-nitrophenol

摘要：

以MOF-74为模板制备了Cu/Co双金属掺杂多孔炭催化剂。用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、N₂物理吸附/脱附等对催化剂结构进行了表征。研究并阐释了Cu/Co双金属掺杂多孔炭催化剂活化过一硫酸盐(PMS)氧化降解4-硝基酚性能及机理。结果表明，在投加100 mg·L^-1催化剂、2 g·L^-1 PMS、初始pH为6时，15 min内硝基酚(60 mg·L^-1)去除率达98%以上。降解反应符合伪一级反应动力学模型。催化剂循环反应4次，降解率均高于90%。猝灭实验及电子顺磁共振分析表明自由基(·SO{}_{\mathrm{4}}^{-}、·OH、·O{}_{\mathrm{2}}^{-})和非自由基(¹O₂)均参与了降解反应。在反应过程中，Co²⁺/Co³⁺和Cu⁺/Cu²⁺的氧化还原循环有效活化了PMS并促进活性氧化物种的生成，从而提升了催化剂降解硝基酚的性能。

关键词: 氧化, 催化剂, 废水, 过硫酸盐, 硝基酚