A comparison of the soil natural oxidant demand exerted by permanganate, hydrogen peroxide, sodium persulfate, and sodium percarbonate

Abstract

In-situ chemical oxidation (ISCO) is based on the delivery of different oxidants to the subsurface where the oxidant is consumed by the contaminants of concern as well as by natural organic matter and other reduced species within the soil. The amount of oxidant consumed by the soil is known as the natural oxidant demand (NOD). Natural oxidant demand is an important screening parameter that helps to determine whether a hazardous waste site is a good candidate for remediation with ISCO. The goal of this study was to assess the soil NOD demand of four different oxidants that included potassium permanganate, hydrogen peroxide, hydrogen persulfate, and percarbonate. The soil natural oxidant demand was determined by measuring the permanganate chemical oxygen demand (PCOD) of the soil before and after chemical oxidation with the various oxidants. The difference in permanganate chemical oxygen demand values is representative of the amount of natural oxidants removed from the soil by each of the oxidants. Equivalent concentrations of each oxidant used (low, medium, and high) were established based on their standard reduction potentials at 25 °C. Each oxidant exhibited a different degree of PCOD removal during oxidation. Although each of the oxidants was shown to interact with the soil, the natural oxidant demand associated with potassium permanganate was the greatest.