Nazmiye Cemre Birben

The role of visible light active TiO2 specimens on the solar photocatalytic disinfection of E. coli.

Solar photocatalytic disinfection efficiency of novel visible light activated (VLA) photocatalysts was evaluated with the aim of assessing inactivation of Escherichia coli as the pathogen indicator organism present in drinking water. Influence of humic acid (HA) on the photocatalytic disinfection efficiency of the specified VLA TiO2 specimens i.e., N-doped, Se-doped, and Se-N co-doped TiO2 was also investigated. Photocatalytic disinfection efficiency was assessed by the enumeration of bacteria following selected irradiation periods. Degradation and compositional changes in organic matter (OM) was also tracked by means of UV-vis and advanced fluorescence spectroscopic (EEM features) parameters. Photocatalytic mineralization of the organic matter was followed by dissolved organic carbon contents. Presence of HA as a model organic compound of natural organic matter (NOM) displayed a retardation effect on solar photocatalytic abatement of E. coli. However, no distinctly different effect was observed under solar photolytic conditions due to the presence of HA. Regrowth of E. coli could not be assessed under the specified experimental conditions. A comparison was introduced with respect to the use of undoped TiO2 P-25 as the photocatalyst.

Adsorption of molecular size fractions of humic acid onto anion-doped TiO2 specimens

AbstractHumic acids (HA) constitute the major fraction of natural organic matter that should be removed during water treatment. Besides conventional treatment methods, application of advanced oxidation processes more specifically photocatalysis has gained much attention in recent decades. Titanium dioxide (TiO2) is universally recognized as a standard photocatalyst. Since photocatalysis occurs through a surface-oriented mechanism, adsorptive properties of TiO2 specimens deserve special attention. Moreover, nowadays visible light activated TiO2 developed by modifications through the use of various dopants has been the subject of numerous investigations. Understanding of the surface interactions prevailing between the anion-doped oxide surface and humic subfractions is important for the determination of the role of humic substances during photocatalysis. The aim of this study was to investigate surface interactions between different molecular size fractions of HA and TiO2, namely bare TiO2 and anion-doped T...