Electrochemical treatment of phenol-containing wastewater by facet-tailored TiO2: Efficiency, characteristics and mechanisms. (15th November 2019)

• Record Type: Journal Article
• Authors: Liu, Chang; Min, Yuan; Zhang, Ai-Yong; Si, Yang; Chen, Jie-Jie; Yu, Han-Qing
• Is Part Of: Water research. Volume 165(2019)
• Publication Date: 2019-11-15
• Subjects: Electrochemical water treatment -- Phenolic pollutants -- Efficiency -- Characteristics -- Mechanism -- TiO2; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2019.114980
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Electrochemical oxidation is widely used for water and wastewater treatment. Anodic material is crucial and the shape-tailored {001}-exposed TiO2 has been proven to be an ideal electrode material for pollutant oxidation. In this work, the electrochemical treatment of wastewater containing typical p -substituted phenols by facet-tailored TiO2 is studied in terms of efficiency, characteristics and mechanisms. Experimental results demonstrate that the anodic oxidation of p -substituted phenols becomes more difficult with the increasing Hammett's constant ( σ ) of phenols, while their degradation rates ( k ) increase continuously with the initial surface concentration ( Γ ). Phenols are degraded mainly by surface-bound ·OH and direct electron transfer on the TiO2 /Ti electrode, rather than by bulk-free ·OH suspended in the aqueous phase. Theoretical calculations reveal that the surface-bound ·OH-mediated oxidation mechanism is attributed mainly to the strong surface bond strength between shape-tailored TiO2 and water molecule as well as the reactive ·OH. Such strong interactions are associated with the higher density of atomic steps, edges and kinks of low-coordinate surface atoms with a large number dangling bonds on the high-energy {001} polar facet. For practical treatment of real wastewater with different matrixes, the facet-tailored TiO2 /Ti electrode exhibits both a high efficiency and a fast kinetics. Our findings provide a new chance to degrade phenolic pollutants in wastewater and offer atomic-scale insights into the preparation, modification and application of TiO2 -based anodic materials for electrochemical water treatment. Graphical abstract: Image 1 Highlights: Electrochemical phenol degradation mechanism by facet-tailored TiO2 was explored. A structure-reactivity relationship was established for the phenol degradation. Strong surface interaction between catalyst and water was main mechanism. Applying TiO2 -based electrode to treat phenol-containing wastewater was demonstrated.