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Nano-sized titania catalyst and transition metal doped titania photocatalysts such as TiO
2
/Ag,
TiO
2
/Cu and TiO
2
/Ag/Cu were used for photocatalytic degradation of Amaranth. Doping of titania
was done with impregnation method. Photocatalytic activity was checked in terms of percentages of
decolorization, COD removal and TOC removal. It was found that TiO
2
/Ag/Cu doped photocatalyst
was more effective for Amaranth dye degradation under feasible treatment conditions. For
decolorization, Amaranth took irradiation time of 210 min with UV/H
2
O
2
but it took only 60 min
with TiO
2
/Ag/Cu doped photocatalyst. Only 29% COD and 49% TOC removal were achieved with
homogeneous photodegradation, whereas with TiO
2
/Ag/Cu heterogeneous photodegradation, 100%
COD and 98% TOC removal was achieved in 9h for 50 ppm aqueous Amaranth solution. The
relative electrical energy consumption per order of magnitude for photocatalytic degradation of
Amaranth was considerably lower with TiO
2
/Ag/Cu catalyst than that with UV/H
2
O
2
and other
combinations of doped photocatalyst. The photocatalysts were characterized using XRD and TEM
analysis.
Different types of dyes are used in many industries such as textile, leather, plastics, paper, food and
cosmetics. During the dyeing process substantial amounts of dyes are not fixed and are released into
the wastewater. The wastewater from textile mills causes serious impact on natural water bodies
and human health hazards such as skin diseases, chemical burns, irritation, ulcers and respiratory
problems. According to estimation 700000 tone dyes are produced annually [1]. Dye house
wastewater usually contains approximately 10-200 ppm of dyes in solution [2]. Among several
classes of dyes, azo dyes are about 60–70% of the dyes used in textile industry. Azo dyes, which
contain one or more unsaturated N=N (azo) bonds, are the most widely used synthetic dyes and are
major dye wastewater pollutants.
Various methods have been applied for the treatment of this colored water was physical adsorption,
biological treatments, ozone treatment, photo-Fenton reaction and advanced oxidation processes
(AOPs) etc. [3]. In the recent years, the use of AOPs has been studied for the complete degradation
of dyes [4]. These processes are based on powerful oxidizing agents such as hydroxyl radicals
(•OH). These hydroxyl radicals have proved to be highly effective for removing refractory organics
from water effluents. In AOP techniques ultraviolet/solar irradiation are used in the presence of
H
2
O
2
, TiO
2,
O
3
and Fenton’s reagent.
Materials Science Forum Vol. 712 (2012) pp 85-104
© (2012) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/MSF.712.85
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,
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