Enhanced photocatalytic removal of hexavalent chromium through localized electrons in polydopamine-modified TiO2 under visible irradiation

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 373; pp. 58 - 67
• Main Authors: Chen, Fengjie, Yu, Wanchao, Qie, Yu, Zhao, Lixia, Zhang, Hui, Guo, Liang-Hong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2019
• Subjects: Cr (VI); Electroplating wastewater; Location electrons generation; Photocatalytic reduction; Polydopamine-modified TiO2; Polydopamine-modified TiO2; Photocatalytic reduction; Location electrons generation; Electroplating wastewater; Cr (VI)
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2019.05.022

[Display omitted] •A highly reductive TiO2/PDA nanocomposite has been obtained.•TiO2/PDA can generate more localized electrons and harvest visible light.•Dramatic photocatalytic removal of Cr (VI) can be achieved in water samples.•Electroplating wastewater (EEW) can be safely and efficiently treated with P25/PDA. Photocatalytic reduction of hexavalent chromium (Cr (VI)) has received widespread attention due to its high toxicity, in which the interfacial electrons generation and transfer on the conduction of the semiconductor surface was the key factor. Herein, Polydopamine (PDA) as hole scavengers and eco-benign polymer, was modified on the TiO2 surface which can not only enhance the hole-electron separation and then generate more long-lived electrons for Cr (VI) reduction but also harvest visible light. Different coated thickness of TiO2/PDA has systematically been investigated for the effect on the electrons generation and reduction treatment ability of Cr (VI), the results showed that TiO2/PDA-15 exhibited the more localized electron, making it advantageous for Cr (VI) removal. The reduction kinetics of Cr (VI) by electrons exhibited two distinct phases: an initial fast reduction and then slow decay removal due to the deposition of Cr (OH)3 solids on the synthesized TiO2 surface in neutral or alkali conditions. While, in the acidic solution, fast removal of Cr (VI) was obtained only within 3 min. A wastewater treatment and a preliminary in vivo study on Daphnia magna experiment suggested that treatment with the TiO2/PDA-15 can effectively remove Cr (VI) and significantly reduce its lethality.