The effect of photocatalytic oxidation on molecular size distribution profiles of humic acid

The influence of photocatalytic degradation on molecular size fractionation (0.45 μm filtered, 100 kDa, 30 kDa and 3 kDa) of humic acid as a model compound of natural organic matter was investigated. The results were evaluated using UV-vis parameters, dissolved organic carbon (DOC) and excitation emission matrix (EEM) fluorescence spectral features. EEM fluorescence signatures displayed an irradiation period dependent transformation of humic-like fluorophores to fulvic-like fluorophores in accordance with the photocatalytic mineralization of HA. Molecular size distribution profiles expressed the formation of lower molecular size (