Pages 28-36
G.R. Dey and P. Singh

DOI: https://doi.org/10.6000/1929-5030.2017.06.01.3

Published: 02 March 2017

Abstract: Photo-catalytic mineralization of eosin in aerated 0.1% (w/v) TiO₂ suspended aqueous systems with and without Au³⁺using 350 nm photo light was carried out. Eosin mineralization rate was significantly faster in 2´10^-4 M Au³⁺ containing systems in contrast to sole TiO₂ systems, which is due to the participation of Au³⁺ and it’s in situ generated various reduced intermediates including gold nanoparticles during mineralization. Furthermore, pulse radiolysis (a well known transient measurement technique) was adopted to analyze the reaction intermediates (eosin-OH adducts and/or eosin radical cation) produced in mineralization by generating in situ ^·OH and N₃^· species. The reaction rates for ^·OH and N₃^· reactions with eosin evaluated respectively 5.4´10⁹ and 3.0´10⁹ dm³ mol^-1 s^-1 for the formation of radical cations were slower than the eosin-OH adduct formation rate (reaction rate = 1.4´10¹⁰ dm³ mol^-1 s^-1). Furthermore, it is proposed that the initially generated eosin-^·OH/hole adduct is undergoing mineralization in the presence of air/oxygen.

Keywords: TiO₂, Photolysis, Au(III) ions, Eosin, Gold nanoparticles, Mineralization.