Decolorization of OrangeII in Aqueous Solution by an Fe(II)/sulfite System: Replacement ofPersulfate.

A novel process for decolorizing dyes with sulfate radicals(SO4•–) using an Fe(II)/sulfitesystem is reported in this manuscript. The objective of this studywas to investigate the conditions under which Fe(II) activates Na2SO3to produce SO4•–and decolorize organic dyes. Orange II, Rhodamine B, Indigo Carmine,and Reactive Brilliant Blue X-BR could be efficiently decolorizedusing this novel system, which was compared with the Fe(II)/persulfateand Fenton (Fe(II)/H2O2) systems. The Fe(II)/sulfitesystem surpassed the other two in the decolorization of these dyes,and detailed mechanisms of the Fe(II)/sulfite system were researched.Primary radical identification through quenching experiments usingtert-butyl alcohol and ethanol confirmed the existence of SO4•–, HO•, and SO5•–. A kinetic model was established forthe halide ion effect, and kI–,SO4•–(3.2 × 1011mol–1L s–1) and RSO4•–f(10–4–10–3mol L–1s–1)were indirectly derived. In conclusion, the Fe(II)/sulfite systemis a good candidate for use in detoxifying water contaminants. [ABSTRACT FROM AUTHOR]