A comparison between Ce（Ⅲ） and Ce（Ⅳ） ions in photocatalytic degradation of organic pollutants

• Published in: 中国稀土学报：英文版 2015, Vol.33 (3), p.249-254
• Main Author: 程强 施薇 段炼 孙彬哲 李晓霞 徐爱华
• Format: Article
• Language: English
• Subjects: Ce（Ⅲ）; 光催化剂; 光催化降解; 有机污染物; 纳米氧化铈; 铈离子; 铈（Ⅲ）
• ISSN: 1002-0721; 2509-4963

Nano cerium oxides are efficient photocatalysts for pollutants degradation with highly dispersed Ce（III） ions as the suggested active species to promote the reaction, while Ce（IV） species do not behave as a catalyst. In this paper, to understand the mechanism of Ce-based photocatalysts, we studied the comparison of simple cerium ions, Ce（III） and Ce（IV） in aqueous solution for organic pollutants degradation under UV irradiation. Orange II（AOII）, methyl orange, and p-nitrophenol were selected as the target pollutants. The formation and contribution of reactive oxygen species, the kinetics of Ce（IV） photoreduction and Ce（III） photooxidation, and the influence of solution p H were investigated in detail. It was found that at low p H Ce（IV） ions showed a higher activity for hydroxyl radicals production and AOII degradation than Ce（III） ions, which could be attributed to its fast reduction rate to Ce（III）. However, its activity dramatically decreased when solution p H increased, and was also strongly influenced by the type of pollutants; while Ce（III） exhibited high degradation efficiency of all the tested pollutants over a wide pH range.