Abstract—Manganese octahedral molecular sieve or cryptomelane (K-OMS2) was synthesized by hydrothermal method and tested as catalytic oxidation of arsenite at different temperatures. The synthesized K-OMS2 was characterized by X-ray diffraction (XRD), Point of zero charge (pHpzc), and Brunauer Emmett Teller (BET). The results showed that K-OMS2 has cryptomelane crystalline structure, pHpzc ≈ 5, and high surface area of 134.76 m2g-1. The results showed that the catalytic oxidation could completely oxidize arsenite to arsenate and the oxidation rate increased as temperature increased in the range of temperature investigated (303 – 333 K). The oxidation kinetic of arsenite fitted well with the pseudo-second-order kinetic model. The oxidation process occurred spontaneously (−ΔG°), in an endothermic nature (+ΔH°), and with increased randomness (+ΔS°). The overall result suggested the potential use of K-OMS2 as a catalytic for the oxidation of arsenite.
Index Terms—Arsenic, oxidation, manganese oxide octahedral molecular sieves, K-OMS2.
J. Phanthasri, B. Pangkumhang, P. Jutaporn, and V. Tanboonchuy are with the Department of Environmental Engineering, Faculty of Engineering, Khon Kaen University, 40002, Thailand (e-mail: jakkapop@kkumail.com, bhuckchanya@gmail.com, panitju@kku.ac.th, and visanu@kku.ac.th).
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Cite: Jakkapop Phanthasri, Bhuckchanya Pangkumhang, Panitan Jutaporn, and Visanu Tanboonchuy, "Kinetics and Thermodynamic Studies of the Arsenite Oxidation by K-OMS2," International Journal of Chemical Engineering and Applications vol. 8, no. 3, pp. 189-193, 2017.
