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(46-46) Photocatalytic degradation of short-chain organic diacids. Domenech, Xavier*,1, Franch, Maribel1, Ayllón, Jose1, Peral, josé, 1 Departament de Química. Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain ABSTRACT- Short organic diacids are metabolites usually present in aquatic environments and which are also produced as intermediates during the degradation of aromatic contaminants in the last steps of the process after cleavage of the aromatic nuclei. As it is well known, these organic diacids show a great tendency to form complexes with metallic cations, contributing to the mobility of heavy metal ions in the environment. Although these organic diacids hardly suffer hydrolysis, in the aquatic media they can be degraded by abiotic processes (oxidation by OH radicals and photolysis), or transformed by microorganisms, giving rise to half-lives of about some months. However, it has been observed that the persistence of fumaric acid in polluted aqueous media is significatively reduced. In these environments, suspended particles are usually present, being some which semiconducting oxides (e.g. ferric oxides, TiO2, ZnO, etc...); under solar irradiation these metallic oxides display photocatalytic activity leading to the degradation of recalcitrant organic compounds. We have studied the photocatalytic degradation of fumaric, maleic and oxalic acids onto TiO2 particles suspended in aqueous media and we have observed a rapid degradation of these compounds. The kinetic rate constants of degradation of the three acids have been determined and the reaction intermediates detected. The mechanism of photocatalytic degradation is discussed. Key words: organic diacids, degradation, photocatalysis, titanium dioxide |
