Decolonization of orange Ⅱ by catalytic oxidation using iron (Ⅲ) phthalocyanine-tetrasulfonic acid

摘要

Orange Ⅱ, C.I. Acid Orange 7 (AO7), is oxidatively decolorized via catalytic oxidation by iron(Ⅲ) phthalocyanine-tetrasulfonic acid (Fe(Ⅲ)-PcTS) as a biomimetic catalyst and KHSO_5 as an oxygen donor. The nature of the decolorization of AO7 was investigated in the catalyst concentration range of 10-50 μM, in which the initial concentration of AO7 was 417 mg l~(-1). A 99.6% decolorization was observed at [KHSO_5] = 2.5 mM and [Fe(Ⅲ)-PcTS] = 20 μM after a 3-h reaction period. However, the fact that only 4.9% of the TOC was removed indicated that the conversion to CO_2 was incomplete. The results of a total organic nitrogen analysis of the reaction mixture showed that the nitrogen in the azo chain was mainly converted to N_2 gas. In addition, 38.6% of the AO7 was converted to 1,2-dihydroxynaphthalene, and 21.4% to p-phenolsulfonic acid. These results indicate that the degradation via this catalytic system involves the conversion of AO7 to phenolic compounds, followed by N_2 production. In addition, a Microtox test showed that toxicity of the solution increased as a result of AO7 oxidation using this catalytic system.