Photochemical pollutant degradation on facet junction-engineered TiO2 promoted by organic arsenical: Governing roles of arsenic-terminated surface chemistry and bulk-free radical speciation

Ai-Yong Zhang; Yang Zhou; Xiao Liu; Nai-Hui Huang; Hai-Hong Niu

doi:10.1016/j.jhazmat.2020.122159

Photochemical pollutant degradation on facet junction-engineered TiO₂ promoted by organic arsenical: Governing roles of arsenic-terminated surface chemistry and bulk-free radical speciation

J Hazard Mater. 2020 May 15:390:122159. doi: 10.1016/j.jhazmat.2020.122159. Epub 2020 Jan 21.

Authors

Ai-Yong Zhang¹, Yang Zhou², Xiao Liu², Nai-Hui Huang², Hai-Hong Niu³

Affiliations

¹ Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, School of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei, 230009, China. Electronic address: ayzhang@hfut.edu.cn.
² Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, School of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei, 230009, China.
³ School of Electrical Engineering and Automation, Hefei University of Technology, Hefei, 230009, China.

PMID: 31999957
DOI: 10.1016/j.jhazmat.2020.122159

Abstract

Photochemical oxidation based on semiconducting metal oxides is an efficient strategy to remove environmental pollutants in water, air and soil. The fine manipulation of photo-carriers separation, surface chemistry and radical speciation is of considerable interest for environmental remediation. In this work, the morphology- and structure-tailored TiO₂ single crystals with epitaxial {101}/{001} facet junction were designed, prepared and tested for photochemical pollutant oxidation in the presence of organic arsenicals, the main component in swine wastewater from livestock industry, although they have been forbidden for several years. The facet junction-tailored TiO₂ deserved an efficient photo-carriers separation with high quantum efficiency. The photochemical oxidation of 4-chlorophenol (4-CP), phenol and bisphenol A (BPA) was substantially improved by roxarsone (ROX). ROX-enhanced photochemical activity of TiO₂ was mainly attributed to the in-situ arsenic-terminated surface chemistry by Ti-OAs^VO₃/-OAs^IIIO₂. This surface played governing roles in water/TiO₂ interactions, and changed water adsorption from dissociative to molecular configuration. Furthermore, ·OH was finely regulated from low-activity surface-bound to high-activity bulk-free speciation between as-generated photo-holes with free water molecules. Our findings provided a new chance to refine the TiO₂-based photochemical oxidation, and a modifying technology to treat swine wastewater from livestock industry with much reduced secondary pollution.

Keywords: Organic arsenicals; Photochemical pollutant oxidation; Radical speciation; Surface chemistry; TiO(2).

Publication types

Research Support, Non-U.S. Gov't