Carbon Modified TiO 2 Photocatalyst with Enhanced Adsorptivity for Dyes from Water
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Carbon Modified TiO2 Photocatalyst with Enhanced Adsorptivity for Dyes from Water M. Janus Æ E. Kusiak Æ A. W. Morawski
Received: 26 November 2008 / Accepted: 5 March 2009 / Published online: 27 March 2009 Ó Springer Science+Business Media, LLC 2009
Abstract A new photocatalyst was obtained by modification of commercial anatase TiO2 (Police, Poland) in a pressure reactor in an ethanol atmosphere at 120 °C for 4 h. The photocatalytic activity of the new material was tested during three azo dyes decomposition: monoazo (Reactive Red 198), diazo (Reactive Black 5) and poliazodye (Direct Green 99). The obtained photocatalyst had new bands at 1,440 cm-1 attributed to CO groups. UV–Vis/DR spectra of the photocatalyst also were changing and had an insignificant decrease in the visible region of the spectra. The amount of hydroxyl radicals produced on carbon-modified TiO2 was a little higher than for the pristine one. The carbon modification also changes the Freundlich model of dyes adsorption to Langmuir model of adsorption. Additionally, it increases the monolayer capacity of modified TiO2. As a result we observed a clear increase of the photocatalytic activity of carbonmodified TiO2 sample. Keywords Carbon-modified TiO2 Photocatalysis Dye decomposition Dye adsorption
M. Janus (&) Department of Sanitary Engineering, West Pomeranian University of Technology, al. Piastow 50, 70-310 Szczecin, Poland e-mail: [email protected] M. Janus E. Kusiak A. W. Morawski Department of Water Technology and Environment Engineering, Institute of Chemical and Environment Engineering, West Pomeranian University of Technology, ul. Pułaskiego 10, 70-322 Szczecin, Poland
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1 Introduction Titanium dioxide is a commercially used in the photocatalytic process of water treatment to eliminate different types of the pollutants [1–5]. To improve photocatalytic activity of TiO2 many kinds of modification were conducted; one of them is carbon modification. In the literature there are three possible ways of modification: titanium dioxide loaded on the surface of activated carbon, carbon coating of TiO2 particles surface and also carbon doping in TiO2 structure. Torimoto et al. [6] prepared photocatalysts by loading TiO2 on activated carbon by using titanium tetraisopropoxide. Aran˜a et al. [7, 8] used a method where TiO2 was loaded on the activated carbon surface by the hydrolytic precipitation of tetraisopropyl orthotitanate. Li et al. [9] prepared TiO2-coated activated carbon (AC) grain (TiO2/AC) through hydrolytic precipitation of TiO2 from tetrabutylorthotitanate and then used heat treatment. TiO2/AC exhibited high photoactivity for the photodegradation of methyl orange (MO) dyestuff in aqueous solution under UV irradiation. Inagaki et al. [10, 11] prepared photocatalysts by carbon coating of titanium dioxide. The catalysts were obtained by mechanical mixing of titanium dioxide with poly(vinyl alcohol) and that mixture was carbonized in an inert atmosphere between 600 and 1,200 °C. Tryba et al. [12] prepared photocatalysts where titanium dio
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