Yan Yaqian, Zhang Xinyi, Wei Jiahao, Chen Miao, Bi Jingtao, Bao Ying
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China.
The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Tianjin 300072, PR China.
ACS Omega. 2022 May 17;7(21):17811-17821. doi: 10.1021/acsomega.2c01031. eCollection 2022 May 31.
Iron- and cobalt-based heterogeneous catalysts are widely applied for activating peroxymonosulfate (PMS) to degrade organic pollutants. However, few studies have unveiled the clear synergistic mechanism of iron and cobalt in ZSM-5. In this paper, the synergistic mechanism of enhanced PMS activation was revealed by constructing iron and cobalt bimetal modified ZSM-5 zeolite catalysts (FeCo-ZSM-5). The tetracycline hydrochloride (TCH) degradation experiments showed that the catalytic activity of FeCo-ZSM-5-2:3 was much higher than those of Fe-ZSM-5 and Co-ZSM-5. In addition, the influences of catalyst dosage, PMS concentration, reaction temperature, initial pH, and coexisting ions on TCH removal were systematically investigated in this paper. Density functional theory calculations indicated that Co was the main active site for PMS adsorption, and Fe increased the area of Co's positive potential mapped to the electron cloud. The Fe-Co bimetallic doping increased the area of positive potential mapped to the electron cloud and benefited the adsorption of PMS on the catalyst surface, which revealed the synergistic mechanism of bimetals. Electron paramagnetic resonance spectra and quenching experiments showed that sulfate radicals, singlet oxygen, and hydroxyl radicals were involved in the degradation of TCH. Furthermore, liquid chromatography-mass spectrometry was conducted to propose possible degradation pathways. This work provides certain guiding significance in understanding the synergistic effect of heterogeneous catalysts for tetracycline wastewater treatment.
铁基和钴基非均相催化剂被广泛应用于活化过一硫酸盐（PMS）以降解有机污染物。然而，很少有研究揭示铁和钴在ZSM-5中的明确协同机制。本文通过构建铁钴双金属改性ZSM-5沸石催化剂（FeCo-ZSM-5）揭示了增强PMS活化的协同机制。盐酸四环素（TCH）降解实验表明，FeCo-ZSM-5-2:3的催化活性远高于Fe-ZSM-5和Co-ZSM-5。此外，本文系统研究了催化剂用量、PMS浓度、反应温度、初始pH值和共存离子对TCH去除的影响。密度泛函理论计算表明，Co是PMS吸附的主要活性位点，Fe增加了映射到电子云的Co正电位面积。Fe-Co双金属掺杂增加了映射到电子云的正电位面积，有利于PMS在催化剂表面的吸附，揭示了双金属的协同机制。电子顺磁共振光谱和猝灭实验表明，硫酸根自由基、单线态氧和羟基自由基参与了TCH的降解。此外，进行了液相色谱-质谱分析以提出可能的降解途径。这项工作对理解非均相催化剂处理四环素废水的协同效应具有一定的指导意义。
