Enhanced Eosin Mineralization in Presence of Au(III) Ions in Aqueous Solutions Containing TiO2 as Suspension
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.