Influence of Peat on Fenton Oxidation

A diagnostic probe was used to estimate the activity of Fenton-derived hydroxyl radicals (•OH), reaction kinetics, and oxidation efficiency in batch suspensions comprised of silica sand, crushed goethite (α-FeOOH) ore, peat, and H2O2 (0.13 mM). A simple method of kinetic analysis is presented and used to estimate the rate of •OH production (POH) and scavenging term (kS), which were used to establish the influence of organic matter (Pahokee peat) in Fenton systems. POH was greater in the peat-amended systems than in the unamended control, and kS was approximately the same. Any increase in scavenging of •OH that resulted from the addition of peat was insignificant in comparison to radical scavenging by reaction with H2O2. Also, treatment efficiency, defined as the ratio of probe conversion to H2O2 consumption over the same period was greater in the peat-amended system. Results suggest that •OH production is enhanced in the presence of peat by one or more peat-dependent mechanisms. Fe concentration and availability in the peat, reduction of Fe(III) to Fe(II) by the organic matter, and reduction of organic-complexed Fe(III) to Fe(II) are discussed in the context of the Fenton mechanism.