Titanium dioxide mediated photocatalytic degradation of 1,2-diethyl phthalate

Abstract

The photocatalyzed degradation of 1,2-diethyl phthalate (DEP) in aqueous suspensions of titanium dioxide has been investigated under a variety of conditions employing a pH-stat technique. The degradation was studied by monitoring the change in substrate concentration employing HPLC analysis and by the decrease in the total organic carbon (TOC) content as a function of irradiation time. The depletion of DEP and TOC was studied under different conditions such as pH, catalyst concentration, substrate concentration, different types of TiO2 as the photocatalyst and in the presence of several electron acceptors (H2O2, KBrO3 and (NH4)2S2O8) in addition to molecular oxygen. Highest degradation rates were observed with Degussa P25 being the photocatalyst at pH 6, while with Sachtleben Hombikat UV 100 smaller decomposition rates were obtained. The degradation of DEP was found to be only slightly enhanced by the addition of electron acceptors, whereas the mineralization is markedly improved in the presence of bromate ions. The degradation products were analyzed by GC–MS technique and probable pathways for the formation of products are proposed.