Chem. J. Chinese Universities ›› 2024, Vol. 45 ›› Issue (3): 20230422.doi: 10.7503/cjcu20230422

• Physical Chemistry • Previous Articles     Next Articles

Mechanism of Molecular Oxygen Activation Mediated by Hydroxyl Groups on the Surface of Red Clay

DU Qing1, NIU Huibin2, XU Yan1, ZHANG Jing1, LAN Xing1, HUANG Yingping2, TAN Yunzhi3, CHEN Xiaoting1, FANG Yanfen1()   

  1. 1.School of Materials and Chemical Engineering
    2.School of Water Resources and Environment
    3.College of Civil Engineering & Architecture,China Three Gorges University,Yichang 443002,China
  • Received:2023-09-25 Online:2024-03-10 Published:2024-01-02
  • Contact: FANG Yanfen E-mail:fangyf@ctgu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(22076098);the Natural Science Foundation of Hubei Province, China(2023AFA054);the 111 Project of China(D20015)

Abstract:

The activation mechanism of molecular oxygen(O2) by surface hydroxyl groups(Me-OH, Me=Al, Si, Fe) of natural clay minerals is still unclear. In this study, red clay(R-Clay) was heat-treated at varying temperatures in N2 to adjust the number and shape of Me-OH sites on its surface, thus activating O2 to different degrees for tetracycline(TC) degradation in water. As the temperature increased, the kaolin structure in R-Clay was gradually destroyed, and the Fe2O3 structure became more prominent. Among them, Me-OH on the surface of red clay (R-Clay400) exists in the form of Al-Al-OH and Al-Si-OH, which efficiently degraded(86.36%) and mineralized TC(40%, 6 h). Under visible light irradiation, both oxygen atoms and TC molecules on R-Clay400 Si-O-Al can be used as electron donors to transfer photogenerated electrons(e-) to O2 adsorbed on the surface of R-Clay400 to form superoxide radical(O2-) and singlet oxygen(1O2), thus achieving efficient degradation of TC. Here, the surface Me-OH, used as the Brönsted site, adsorbs O2 by hydrogen bond, which promotes electron transfer rather than traditional electron donor. This study further clarified the activation mechanism of clay minerals to O2 and promoted the development of related research fields of mineral-based materials.

Key words: Heat treatment, Red clay, Surface hydroxyl group, Molecular oxygen activation mechanism, Degradation

CLC Number: 

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