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.
Highlights
Color removal from industrial effluent is one of the most difficult requirements faced by the textile, dye manufacturing and paper industries
The aerated (10 min air purged) aqueous solutions containing 0.1% (w/v) TiO2 as suspension and 2×10-4 M eosin were photo-irradiated with constant stirring for different time at room temperature and normal atmospheric pressure
Enhanced mineralization of eosin has been demonstrated under the study in presence of both Au(III) ions and its’ in situ generated AuNP in oxygen containing systems
Summary
Color removal from industrial effluent is one of the most difficult requirements faced by the textile, dye manufacturing and paper industries. These industries are major consumers of water and, cause water pollution; afterward it spreads to air and soil pollutions. Most of the dyes are harmful when brought in contact with living tissues. The discharge of such dyes into the river stream without proper treatment causes irretrievable damage to the crops and living beings, both aquatic and terrestrial. Mineralization of eosin, a model dye chosen under the study is generally used in cosmetics and biological stain for studying cell structures. Eosin is a carcinogen [1], it causes cheilitis, dermatitis and stomatitis and emits toxic fumes when heated [2]
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