title: Evaluation of natural organic matter changes from Lake Hohloh by three-dimensional excitation-emission matrix fluorescence spectroscopy during TiO(2)/UV process.
abstract: This study shows the changes of natural organic matter (NOM) from Lake Hohloh, (Black Forest, Germany) during heterogeneous photocatalysis with TiO2 (TiO2/UV). The effect of pH on the adsorption of NOM onto TiO2 in the dark and TiO2/UV degradation of NOM was followed using three-dimensional excitation-emission matrix (EEM) fluorescence. At pH values between 4 and 9, the NOM was adsorbed onto TiO2 in the dark with a greater decrease in the fluorescence intensity and in the spectral shapes, especially under acidic pH conditions. However, at pH = 10 there was not adsorption on NOM which led to a negligible changes the fluorescence intensity. A significant high linear correlation was observed between the DOC adsorption onto TiO2 and the maximum fluorescence intensity. Additionally, the NOM adsorption onto TiO2 and its TiO2/UV degradation shifted the fluorescence maxima toward shorter wavelengths in the EEM contour plots, with a decrease in aromaticity. These changes were accompanied by a substantial decrease in the organically bound halogens adsorbable on activated carbon (AOXFP) and the trihalomethane formation potential (THMFP). Thus, the decrease in maximum fluorescence intensity can be used as an indicator of AOXFP and TTHMFP removal efficiency. Therefore, fluorescence spectroscopy is a robust analytical technique for evaluate TiO2/UV removal of NOM.
authors.affiliation: Grupo Procesos Fisicoquímicos Aplicados, Facultad de Ingeniería, Universidad de Antioquia, SIU/UdeA, calle 70 No. 52-21 Medellín, Colombia. Electronic address: hvalens@gmail.com.
authors.forename: Sergio
authors.initials: S
authors.lastname: Valencia
authors.affiliation: Grupo Procesos Fisicoquímicos Aplicados, Facultad de Ingeniería, Universidad de Antioquia, SIU/UdeA, calle 70 No. 52-21 Medellín, Colombia.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Marín
authors.affiliation: Grupo Procesos Fisicoquímicos Aplicados, Facultad de Ingeniería, Universidad de Antioquia, SIU/UdeA, calle 70 No. 52-21 Medellín, Colombia.
authors.forename: Gloria
authors.initials: G
authors.lastname: Restrepo
authors.affiliation: Bereich Wasserchemie, Engler-Bunte-Institut, Karlsruher Institut für Technology (KIT), 7631 Karlsruhe, Germany. Electronic address: fritz.frimmel@kit.edu.
authors.forename: Fritz H
authors.initials: FH
authors.lastname: Frimmel
mesh_terms: D000327:Adsorption; D005858:Germany; D006812:Humic Substances / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D060106:Lakes; D010782:Photolysis; D013050:Spectrometry, Fluorescence; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D006812:Humic Substances; C009495:titanium dioxide; D014025:Titanium
keywords: Excitation–emission matrix; Fluorescence spectroscopy; Heterogeneous photocatalysis; Natural organic matter