Application of excitation–emission fluorescence matrices and UV/Vis absorption to monitoring the photocatalytic degradation of commercial humic acid Sergio Valencia a, ⁎, Juan M. Marín a , Gloria Restrepo a , Fritz H. Frimmel b, ⁎⁎ a Procesos Fisicoquímicos Aplicados, Universidad de Antioquia, Carrera 53 # 61-30, Medellín, Colombia b BereichWasserchemie, Engler-Bunte-Institut, Karlsruher Institut für Technology (KIT), 7631, Karlsruhe, Deutschland HIGHLIGHTS ► There is a strong correlation between the fluorescence intensity of humic acids and DOC. ► HA-like and FA-like fluorescence inten- sity and SUVA show strong linear corre- lation. ► Humic acids with high fluorescence in- tensity imply high formation of DBPs. ► Humic acid photocatalysis lead to a de- crease in the fluorescence intensity of EEMs. ► Fluorescence spectroscopy is a pow- erful tool to monitor HA photocata- lytic removal. GRAPHICAL ABSTRACT abstract article info Article history: Received 16 May 2012 Received in revised form 14 October 2012 Accepted 14 October 2012 Available online 22 November 2012 Keywords: Humic acids Heterogeneous photocatalysis Fluorescence spectroscopy Excitation–emission matrix This study reports the use of excitation–emission matrix (EEM) fluorescence and UV/Vis spectroscopy to monitor the changes in the composition and reactivity of Aldrich humic acids (Aldrich HA) as a model compound for natural organic matter (NOM) during photocatalytic degradation. Degussa P-25 titanium dioxide (TiO 2 ) and a solar UV-light simulator (a batch reactor) were used. The photocatalysis shifted the fluorescence maxima of EEMs of Aldrich HA toward shorter wavelengths, which implied that the photocatalytic degradation of commercial Aldrich HA caused the breakdown of high molecular weight components and the formation of lower molecular weight fractions. In addition, the fluorescence intensity of fulvic- and humic-like Aldrich HA presented a strong correlation with dissolved organic carbon (DOC), specific UV absorbance (SUVA) parameters, trihalomethane formation potential (THMFP), and organically bound halogens absorbable on activated carbon formation poten- tial (AOXFP). Fluorescence spectroscopy was shown to be a powerful tool for monitoring of the photocatalytic degradation of HA. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Humic substances (HSs) are a major component of natural organic matter (NOM) and are the dominant products of plant and animal degradation by microbial activity. HSs present a high degree of aromatic character and include different functional groups, such as carboxylic and phenolic moieties (Maia et al., 2008; Matilainen et al., 2011). HSs influ- ence the binding and transport of pesticides and other nonpolar organic compounds (Florentino et al., 2006; Frimmel and Abbt-Braun, 2009). Moreover, HSs are well known to be precursors of carcinogenic and mu- tagenic disinfection byproducts (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs) (Richardson et al., 2007; DeMarini, 2011). HAs are also responsible for the high concentration of other organically Science of the Total Environment 442 (2013) 207–214 ⁎ Corresponding author. Tel./fax: +57 4 2196543. ⁎⁎ Corresponding author. Tel.: +49 721608x4 2580; fax: +49 721 699154. E-mail addresses: hvalens@gmail.com (S. Valencia), fritz.frimmel@kit.edu (F.H. Frimmel). 0048-9697/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.scitotenv.2012.10.058 Contents lists available at SciVerse ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv