Boosting the activation of molecular oxygen and the degradation of tetracycline over high loading Ag single atomic catalyst

Zhiruo Zhou; Zhurui Shen; Chunlin Song; Mingmei Li; Hui Li; Sihui Zhan

doi:10.1016/j.watres.2021.117314

Boosting the activation of molecular oxygen and the degradation of tetracycline over high loading Ag single atomic catalyst

Water Res. 2021 Aug 1:201:117314. doi: 10.1016/j.watres.2021.117314. Epub 2021 May 31.

Authors

Zhiruo Zhou¹, Zhurui Shen², Chunlin Song¹, Mingmei Li¹, Hui Li³, Sihui Zhan⁴

Affiliations

¹ MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
² MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; School of Materials Science and Engineering, Nankai University, Tianjin 300350, China. Electronic address: shenzhurui@nankai.edu.cn.
³ School of Materials Science and Engineering, Nankai University, Tianjin 300350, China.
⁴ MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; Tianjin Key Lab for Rare Earth Materials and Applications, Tianjin 300072, China. Electronic address: sihuizhan@nankai.edu.cn.

PMID: 34146763
DOI: 10.1016/j.watres.2021.117314

Abstract

Photocatalytic activation of molecular oxygen (O₂) is a promising way in oxidative degradation of organic pollutants. However, it suffers from low efficiency mainly due to the limited active sites for O₂ activation over traditional photocatalysts. Therefore, we established a single atomic Ag-g-C₃N₄ (SAACN) catalyst with 10 wt% loading of Ag single sites for boosting the O₂ activation during the degradation of tetracycline (TC), and 10 wt% loading of nanoparticle Ag-g-C₃N₄ (NPACN) was studied as a comparison. When using SAACN, the accumulative concentration of superoxide (•O₂^-), hydroxyl radical (•OH), singlet oxygen (¹O₂) reached up to 0.66, 0.19, 0.33 mmol L^-1h^-1, respectively, within 120 min, 11.7, 5.7 and 4.9 times compared with those using NPACN, representing 17.24% of dissolved O₂ was converted to reactive oxygen species (ROS). When additionally feeding air or O_2, the accumulative concentrations of •O₂^-, •OH, ¹O₂ were even higher (air: 4.21, 0.97, 2.02 mmol L^-1 h^-1; O₂: 17.13, 1.32, 9.00 mmol L^-1 h^-1). The rate constants (k) for degrading the TC were 0.0409 min^-1 over SAACN and 0.00880 min^-1 over NPACN, respectively (mineralization rate: 95.7% vs. 59.9% after 3 h of degradation). Moreover, the degradation ability of SAACN did not decrease in a wide range of pH value (4-10) or under low temperature (10 °C). Besides the high exposure of Ag single sites, other advances of SAACN were: 1(O₂ was more energetic favorable to adsorb on single atomic Ag sites; 2) Positive Ag single sites were easier to obtain the electrons from the surrounding N atoms, and facilitated electron transfer towards adsorbed O₂.

Keywords: Activation of molecular oxygen; Interfacial behaviors; Single atomic catalyst; Tetracycline degradation.

MeSH terms

Anti-Bacterial Agents
Catalysis
Oxygen
Silver*
Tetracycline*

Substances

Anti-Bacterial Agents
Silver
Tetracycline
Oxygen