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Open AccessArticle

Solar and Visible Light Illumination on Immobilized Nano Zinc Oxide for the Degradation and Mineralization of Orange G in Wastewater

Institute of Environmental Engineering, Hungkuang University, Taichung 433, Taiwan
Author to whom correspondence should be addressed.
Academic Editors: Shaobin Wang and Xiaoguang Duan
Catalysts 2017, 7(5), 164;
Received: 4 March 2017 / Revised: 2 May 2017 / Accepted: 10 May 2017 / Published: 20 May 2017
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
PDF [3530 KB, uploaded 20 May 2017]


An advanced oxidation process (AOP) utilizing immobilized zinc oxide (ZnO) photocatalyst was employed to decolorize and mineralize orange G (OG) azo dye in wastewater under solar and visible light irradiation. This AOP employed visible light and ZnO in a so-called Vis/ZnO process. Operating parameters, including ZnO dosage, initial OG concentration, pH, visible-light intensity, catalyst loaded area, and treatment volume were investigated to illustrate their influences on OG degradation and mineralization. From the results, neither visible light alone, nor the ZnO adsorption process could degrade or remove OG from wastewater. However, for the Vis/ZnO process, the higher ZnO dosage and visible light intensity are two major parameters to improve the OG degradation and total organic carbons (TOC) mineralization. The initial pH of 11 was the most effective pH condition on the OG degradation. The first-order rate constant is exponentially decreased from 0.025 to 0.0042 min−1 with the increase of the initial OG concentration and an empirical equation can be derived to estimate the first-order rate constant with a known initial OG concentration. In contrast, the first-order rate constant is linearly increased from 0.0027 to 0.0083 min−1 by increasing the visible light intensity. The results present that the Vis/ZnO process is an effective AOP for the degradation of OG in wastewater. View Full-Text
Keywords: ZnO; visible light; photocatalytic degradation; orange G; immobilization ZnO; visible light; photocatalytic degradation; orange G; immobilization

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Shu, H.-Y.; Chang, M.-C.; Tseng, T.-H. Solar and Visible Light Illumination on Immobilized Nano Zinc Oxide for the Degradation and Mineralization of Orange G in Wastewater. Catalysts 2017, 7, 164.

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