A novel scheme to improve the photo-Fenton performance of iron oxychloride by carbon: Three existent states and roles of carbon in the degradation of tetracycline in water

Lina Wang; Hanpei Yang; Yuankun Yang; Zuming He

doi:10.1016/j.jcis.2023.03.113

A novel scheme to improve the photo-Fenton performance of iron oxychloride by carbon: Three existent states and roles of carbon in the degradation of tetracycline in water

J Colloid Interface Sci. 2023 Jul:641:916-928. doi: 10.1016/j.jcis.2023.03.113. Epub 2023 Mar 22.

Authors

Lina Wang¹, Hanpei Yang², Yuankun Yang¹, Zuming He¹

Affiliations

¹ Key Laboratory of Integrated Regulation and Resource Development, on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
² Key Laboratory of Integrated Regulation and Resource Development, on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China. Electronic address: yanghanpei@hhu.edu.cn.

PMID: 36972626
DOI: 10.1016/j.jcis.2023.03.113

Abstract

The photo-Fenton process is promising for sincerely treating contaminated water. In this work, carbon-decorated iron oxychloride (C-FeOCl) is synthesized as a photo-Fenton catalyst for removing tetracycline (TC) from water. Three actual states of carbon are identified and their different roles in enhancing photo-Fenton performance are revealed. All carbon on/in FeOCl, including graphite carbon, carbon dots and lattice carbon, enhance visible light adsorption. More importantly, a homogeneous graphite carbon on the outer surface of FeOCl accelerates the transportation-separation of photo-excited electrons along the horizontal direction of FeOCl. Meanwhile, the interlayered carbon dots offer a FeOC bridge in helping the transportation-separation of photo-excited electrons along the vertical direction of FeOCl. In this way, C-FeOCl acquires isotropy in conduction electrons to ensure an efficient Fe(II)/Fe(III) cycle. These interlayered carbon dots extend the layer spacing (d) of FeOCl to about 1.10 nm, exposing the internal iron centers. The lattice carbon significantly increases the amounts of coordinatively unsaturated iron sites (CUISs) in activating hydrogen peroxide (H₂O₂) to hydroxyl radical (OH). Density functional theory (DFT) calculations confirm this activation on inner and external CUISs with a significantly low activation energy of about 0.33 eV.

Keywords: Carbon; Existent state; Fe (II)/Fe(III) cycle; FeOCl; Isotropy; Photo-Fenton.