title: Degradation of organic molecules in advanced oxidation processes: relation between chemical structure and degradability.
abstract: Hydroxyl radical induced degradation of maleic acid, fumaric acid and 20 aromatic molecules was investigated in air saturated aqueous solutions. Hydroxyl radicals were generated by an advanced oxidation process (AOP), water radiolysis. Oxidation was followed by chemical oxygen demand (COD) and total organic carbon content (TOC) measurements. Up to ∼30-50% decrease of COD the dose dependence was linear. By the ratio of the decrease of COD and the amount of reactive radiolysis intermediates introduced into the solution the oxidation efficiencies were calculated. Efficiencies around 0.5-1 (O2 molecule built in products/OH) found for most of the compounds show that the one-electron-oxidant OH induces 2-4 electron oxidations. The high oxidation rates were explained by OH addition to unsaturated bonds and subsequent reactions of dissolved O2 with organic radicals. In amino substituted molecules or in Acid Red 1 azo dye, O2 cannot compete efficiently with unimolecular transformation of organic radicals and the efficiency is lower (0.2-0.5).
authors: Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary.
authors: Renáta
authors: R
authors: Homlok
authors: Erzsébet
authors: E
authors: Takács
authors: László
authors: L
authors: Wojnárovits
mesh_terms: D057919:Biological Oxygen Demand Analysis; D017665:Hydroxyl Radical / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry*; D010084:Oxidation-Reduction; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D017665:Hydroxyl Radical