Promotion effect of KMnO4 on the oxidation of As(III) by air in alkaline solution

• Published in: Journal of hazardous materials Vol. 280; pp. 315 - 321
• Main Authors: Li, Yuhu, Liu, Zhihong, Liu, Fupeng, Li, Qihou, Liu, Zhiyong, Zeng, Li
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.09.2014; Elsevier
• Subjects: Air oxidation; Applied sciences; Arsenic oxidation; Catalysis; Catalytic oxidation; Catalytic reactions; Chemical engineering; Chemistry; Exact sciences and technology; General and physical chemistry; Pollution; Potassium permanganate; Promotion effect; Reactors; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Catalytic oxidation; Air oxidation; Potassium permanganate; Arsenic oxidation; Promotion effect; Permanganates; Catalytic reaction; Arsenic; Arsenites; First order; pH; Oxidation; Kinetics; Catalyst
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2014.08.008

The mechanism of the oxidation of arsenic by air in the presence of KMnO4: (a) Oxidation of Mn2+ and formation of MnO2; (b) Catalytic oxidation of arsenic; (c) Oxidation of arsenic by dissolved oxygen; (d) Dissolution and precipitation of Mn2+. •KMnO4 shows superstoichiometric oxidation for arsenic in solution.•Adding KMnO4 to alkaline solution could improve the kinetics of arsenic oxidation.•MnO2 acts as a catalyst to prompt reaction between As(III) and dissolved oxygen.•The mole ratio of As/Mn and pH has significant effects on As(III) oxidation.•The adsorption and desorption of MnO2 with As(III) and oxygen occurs. The mechanism of oxidation of As(III) in alkaline solution by air with promotion effect of KMnO4 was studied. The experimental results indicated that the superstoichiometric oxidation of As(III) by KMnO4 could be attributed to the catalytic effect of reductive product of KMnO4. The XRD and XPS results demonstrated that the catalyst was nascent MnO2 rich in potassium. The results also showed that the mole ratio of Mn/As and the initial pH had significant effects on the oxidation of As(III). The time for the oxidation by air was less than 2h with the mole ratio of Mn/As less than 1/10.5 and the initial pH higher than 13. The kinetics of the catalytic oxidation of arsenic was interpreted using the pseudo first order reaction, and the apparent active energy was about 15.01kJ/mol. The study suggested that the initial oxidation was firstly dominated by the direct oxidation of KMnO4 followed by the catalytic oxidation with the nascent MnO2.