Chemical oxidation of polycyclic aromatic hydrocarbons using ferric complexes

Abstract

Seven ferric complexes were synthesised and applied as Fenton-like oxidation catalysts to six polycyclic aromatic hydrocarbons (PAHs) under aqueous conditions using hydrogen peroxide as the oxidant. Two of these catalysts were also applied to PAH-contaminated soil under laboratory conditions. Individual and mixed PAH reactions involving each of the ferric catalysts were performed in aqueous buffer solutions at pH 5, 7 and 10, whilst the individual reactions were also carried out in unbuffered aqueous solution. Reactions were also performed to determine the catalytic ability of each of the ferric catalysts, whilst additional reactions were carried out to ascertain the affect of the unbound ligands on anthracene and also whether the ferric catalysts were able to oxidise 9,10-anthracendione, an oxidation product of anthracene. For comparison purposes the individual PAH reactions were also performed using the classical Fenton's reagent (FeIISO4) at pH5. All of the ferric catalysts were effective towards the oxidation of anthracene, acenaphthene, phenanthrene, fluoranthene and pyrene, and were slightly less effective towards catalysing the oxidation of chrysene. At pH 5 all of the ferric catalysts were shown to be significantly better catalysts than the Fenton's reagent towards catalysing the oxidation of these PAHs. Soil trials indicated that although the ferric catalysts used in conjunction with hydrogen peroxide are effective in catalysing the oxidation of PAHs in soil, the results were similar to those obtained by Fenton's reagent and indicate that further investigation is warranted to ascertain the optimum reaction conditions for the ferric catalysts.