Fluorescence Excitation-Emission Spectroscopy for Characterizing Transformation of Dissolved Organic Matter during Landfill Leachate Treatment by Photocatalysis

Fluorescence spectroscopy was performed to investigate the composition changes and characteristics of the leachate DOM (dissolved organic matter) during UV-TiO2photocatalytic treatment process. The results showed that fulvic-like, tryptophan-like and humic acids-like matters were the main compounds in leachate. During photocatalytic treatment process, fluorescence spectroscopy of DOM changed considerably. The final products were mainly fulvic-like and tryptophan-like matters. In general, the fluorescence signals of humic acids-like matters had the most significant change, which disappeared entirely after 60 h treatment, implying that humic acids-like matters can be degraded preferentially by photocatalysis. The other notable change was in VIS fulvic-like matters region, which suggested that fulvic-like matters can be significantly degraded. In 72 h photocatalytic effluent, VIS fulvic-like, tryptophan-like and tyrosine-like matters were remained, and the last two matters were the dominant fractions. These results indicated that fulvic-like and humic acids-like matters with macromolecular can be degraded into protein-like matters with micro-molecular by photocatalysis.