Simple and Sensitive Detection of Persulfate Based on a Resonance Light Scattering Spectroscopy
Abstract With the increasingly extensive application of persulfate for water treatment, the development of persulfate detection technology has gradually become a research hotspot. Ferrous ions can catalyze peroxydisulphate (PDS) to produce \({\text{SO}}_{4}^{ - }• \) and \(• {\text{OH}}\) , which oxidize excessive KI to form \({\text{I}}_{3}^{ - }\) . Then \({\text{I}}_{3}^{ - }\) and cationic dye (Basic Blue 54) form ion association complex through electrostatic interaction. These complexes aggregate to form particles with the average size of 362 nm. Formation of ion association particles leads to sharp enhancement of resonance scattering intensity of the system. Based on this principle, a new method for the resonance light scattering determination of peroxydisulphate has been developed, and the optimum reaction conditions, influential factors and applications were investigated. Initial solution pH of 4.5, initial Fe 2+ concentration of 3.0 × 10 –6 mol L –1 , KI concentration of 1.0 × 10 –3 mol L –1 , BB54 concentration of 2.0 × 10 –5 mol L –1 , these conditions were selected as the optimized initial concentration for the detection of PDS. Under the optimal reaction conditions, peroxydisulphate concentrations of 2.5 × 10 –7 –1.8 × 10 –5 mol × L –1 were linearly correlated with the reduction of the resonance light scattering intensity with a correlation coefficient of 0.99 and a detection limit of 7.8 × 10 –8 mol L –1 . This method of measuring PDS shows a higher sensitivity than other methods. The interferences of coexisting substances were also investigated. It has been applied to the analysis of peroxydisulphate in water samples. The recovery rates of the spiked samples were in the range between 91.1–106.2% which showed that the method had high accuracy for the analysis of peroxydisulphate.
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