Persulfate is an emerging oxidant for in situ chemical oxidation (ISCO) applications with a high oxidation potential on activation (Eo = 2.6 V). The design of an oxidant remedial system involves a comprehensive understanding of a number of underlying physical and chemical processes. One of these processes, which impacts oxidant efficiency, involves the stability of the oxidant in the presence of natural aquifer materials. To improve our understanding and develop predictive relationships a series of batch experiments were designed to quantify the interaction between persulfate and aquifer materials. Well-characterized aquifer materials collected from seven sites across North America were used in this investigation. The batch experiments, run in triplicates for each aquifer material, were conducted to primarily observe and derive decomposition kinetic parameters for an experimental system that comprised of 100 g of solids, and 100 mL of solution with an initial persulfate concentration of 1000 mg/L. The decomposition of persulfate followed a first-order mass action law in the presence of all aquifer materials used in this study although the reaction rate coefficient varied by an order of magnitude (10-4 to 10-3 hr-1). In general, the observed reaction rate coefficients were small indicating that persulfate will have a high stability in these aquifer systems. Preliminary test results suggest that persulfate decomposition is a function of the oxidant to solids mass ratio. Dissolved organic carbon, iron, and manganese concentrations decreased relative to background conditions; however, no correlation with the observed reaction rate coefficients was determined. Significant decreases in the chemical oxidant demand of solids exposed to persulfate indicate that oxidation of natural organic matter occurred in these batch systems.
Sra, Kanwartej S.; Whitney, Jessica J.; Thomson, Neil R.; and Barker, Jim F.
"Persulfate Decomposition Kinetics In The Presence Of Aquifer Materials,"
Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy:
Vol. 12, Article 29.
Available at: http://scholarworks.umass.edu/soilsproceedings/vol12/iss1/29