New photocatalyst for decomposition of humic acids in photocatalysis and photo-Fenton processes

Abstract

Humic acid Leonardite IHSS standard was decomposed on TiO 2 and TiO 2 modified by FeC 2O 4 via the photocatalysis and photo-Fenton processes under UV irradiation. Humic acid (HA) were favorable adsorbed on TiO 2 surface and followed decomposition during UV irradiation faster on TiO 2 than on the modified samples. However, when H 2O 2 was added to the solution, the photo-Fenton process occurred on the prepared TiO 2 samples, contained iron together with photocatalysis and high acceleration of HA decomposition was observed. In this case the mineralization degree was much higher than in the applied photocatalysis only, around 75% HA (with concentration of 18 mg/L) was mineralized after 3 h of adsorption and 5 h of UV irradiation in the presence of H 2O 2 and modified TiO 2 whereas on TiO 2 mineralisation of HA occurred in around 45% only. The measured fluorescence spectra of HA solutions showed that in the presence of H 2O 2 polycyclic aromatics were rapidly oxidized to the lower size products such as alcohols, aldehydes, ketones and carboxylic acids, what accelerated the process of HA decomposition.