The catalytic aerial oxidation of As(III) in alkaline solution by Mn-loaded diatomite

• Published in: Journal of environmental management 2022-09, Vol.317, p.115380-115380, Article 115380
• Main Authors: Yang, Yudong, Zhang, Zhongtang, Li, Yuhu, Wang, Ruixiang, Xu, Zhifeng, Jin, Chengyong, Jin, Guizhong
• Format: Article
• Language: English
• Subjects: Arsenic; Arsenic oxidation; Catalytic oxidation; Diatomite; Mn-loaded catalyst
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2022.115380

The oxidization of As(III) to As(V) is necessary for both the detoxification of arsenic and the removal of arsenic by solidification. In order to achieve high efficiency and low cost As(III) oxidation, a novel process of catalytic aerial oxidation of As(III) is proposed, using air as oxidant and Mn-loaded diatomite as a catalyst. Through systematic characterization of the reaction products, the catalytic oxidation reaction law of Mn-loaded diatomite for As(III) was found out, and its reaction mechanism was revealed. Results show that Mn-loaded diatomite achieved a good catalytic effect for aerial oxidation of As(III) and maintained high performance over multiple cycles of reuse, which was directly related to the structure of diatomite and the behavior of manganese. Under the conditions of a catalyst concentration of 20 g/L, an air flow rate of 0.3 m3/h, a reaction temperature of 50 °C and an initial pH of 12.6, 96.04% As(III) oxidation was achieved after 3 h. Furthermore, the efficiency of As(III) oxidation did not change significantly after ten cycles of reuse. XPS analysis of the reaction products confirmed that the surface of the catalyst was rich in Mn(III), Mn(IV) and adsorbed oxygen(O–H), which was the fundamental reason for the excellent performance of Mn-loaded diatomite in the catalytic oxidation of As(III). [Display omitted] •The Mn-loaded diatomite can effectively adsorb and oxidize As(III).•The As(III) oxidation efficiency is more than 200 times higher than that of air alone.•The active material for the oxidation of As(III) is Na0.55Mn2O4∙1.5H2O.•The catalyst can be reused without desorption-regeneration treatment.•The extent of As(III) oxidation maintained above 90% throughout ten cyclic runs.