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Abstract
Due to a gradual increase in the use of persulfate as an in situ chemical oxidation
(ISCO) oxidant, a simple measurement of persulfate concentration is desirable to analyze
persulfate distribution at designated time intervals on/off a site. Such a distribution
helps evaluate efficacy of ISCO treatment at a site. This work proposes a spectrophotometric
determination of persulfate based on modification of the iodometric titration method.
The analysis of absorption spectra of a yellow color solution resulting from the reaction
of persulfate and iodide in the presence of sodium bicarbonate reveals an absorbance
at 352 nm, without significant interferences from the reagent matrix. The calibration
graph was linear in the range of persulfate solution concentration of 0-70 mM at 352
nm. The proposed method is validated by the iodometric titration method. The solution
pH was at near neutral and the presence of iron activator does not interfere with
the absorption measurement. Also, analysis of persulfate in a groundwater sample using
the proposed method indicates a good agreement with measurements by the titration
method. This proposed spectrophotometric quantification of persulfate provides a simple
and rapid method for evaluation of ISCO effectiveness at a remediation site.