Due to a gradual increase in the us

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.