Degradation of polycyclic aromatic hydrocarbons by hydrogen peroxide catalyzed by heterogeneous polymeric metal chelates

Chelating sorbents with 8-hydroxyquinoline (IVa), 8-hydroxyquinoline-5-sulfonic acid (IVb), and tris(2-aminoethyl)amine (VI) ligands immobilized on macroporous methacrylate matrix were prepared and saturated with Co(II), Cu(II), and Fe(II). All these chelates catalyze cleavage of H2O2 yielding highly reactive hydroxyl radicals. All were able to degrade by this mechanism polycyclic aromatic hydrocarbons (anthracene, benzo[a]pyrene and benzo[k]fluoranthene). The most effective catalysts IVa-Fe, IVb-Fe, and VI-Cu (25 mg with 100 μmol H2O2) performed complete decomposition of 33 μg anthracene and benzo[a]pyrene during one 7-day catalytic cycle at 25 °C. The fastest decomposition proceeded during the 1st day of incubation; 75% of anthracene and 74% of benzo[a]pyrene were decomposed by IVb-Co within the first 24 h. More than 25% decomposition within the 1st day was also achieved with IVb-Fe, VI-Cu, IVa-Cu, and VI-Co for anthracene and more than 30% benzo[a]pyrene was decomposed by IVb-Fe, VI-Cu, IVa-Cu, and IVb-Cu during the same period. 1,4-Anthracenedione was the main product of anthracene oxidation by all catalysts. The catalysts were stable at pH 2-11 depending on their structure and able to perform sequential catalytic cycles without regeneration.