Spectrophotometric determination of persulfate anion via oxidative depolarization of methyl orange induced by ferrous ions. Issue 52 (7th November 2016) - Zhang, Jianqiao
Abstract: A rapid, simple, and sensitive spectrophotometric method was developed for the determination of persulfate in this study, based on the oxidation decolorization of methyl orange (MO) with sulfate radicals and hydroxyl radicals generated by the conjunction of persulfate with ferrous ions. The depletion of MO at its maximum absorption wavelength (507 nm) is in proportion to the concentration of persulfate in water. There was a good linear relationship (above 99%) between the depletion of MO and the concentration of persulfate in the ranges of 0.5–100 μmol L −1 with a detection limit of 0.17 μmol L −1 under the optimized conditions. The proposed MO method for the determination of persulfate in water was effective to tolerate the interferences of common coexisting foreign species in aqueous solutions. The results were as satisfactory as that obtained by the classical iodometric method used in practical water samples. Additionally, the proposed MO method is rather inexpensive to measure the concentration of persulfate by using standard laboratory instruments (spectrophotometer).