Rapid spectrophotometric determination of peroxymonosulfate in water with cobalt-mediated oxidation decolorization of methyl orange

In this study, a rapid, simple and sensitive spectrophotometric method for the determination of peroxymonosulfate (PMS) in aqueous solutions was developed, which is based on the oxidation decolorization of methyl orange (MO) with sulfate radicals generated by the conjunction of PMS with cobalt. The depletion of MO at 464 nm (the maximum absorption wavelength of MO) is in proportion to the concentration of PMS in aqueous solutions. Under the optimized conditions, a good linear relationship (r = 0.9997) was established between the depletion of MO and the concentration of PMS in the ranges of 0.5-100 mu mol L-1 with a detection limit of 0.09 mu mol L-1. The proposed MO method for the determination of PMS was well effective to tolerate the interferences of common coexisting foreign species in aqueous solutions. When the proposed MO method was used to determine the concentration of PMS in practical samples, the results were as satisfactory as that obtained by the classical iodometric method. (C) 2014 Elsevier B.V. All rights reserved.