Studies on photodegradation of malachite green using TiO2/ZnO photocatalyst

Abstract

Wastewater containing dyes emanating from textile mills is strongly colored and is carcinogenic in nature. In order to reduce pollution load it is desirable to degrade the dye into non-toxic form before its discharge into the main stream. The present paper reports the photocatalytic degradation of malachite green (MG). MG is used to dye materials like silk, paper and leather. The batch experiments were carried out by irradiating the aqueous solution of dye in the presence of photocatalysts and UV light. The photocatalysts used for the study are titanium dioxide (TiO 2), zinc oxide (ZnO), and different ratios of ZnO and TiO 2. The rate of decolorization was estimated from residual concentration spectrophotometrically. The effect of process parameters viz. pH 2-9, initial concentration of dye 5-50 ppm and amount of catalyst 0.5-1.5 g/l on degradation of the dye has also been assessed. The experimental results indicated that , ZnO efficiently compete with TiO 2 in terms of percentage degradation of MG. Maximum degradation of dye occurs in acidic range with TiO 2 and at neutral pH with ZnO. When photocatalysts are mixed in different ratios, best results were obtained with ZnO and TiO 2 in the ratio of 9:1.The high decolorizing efficiency was obtained with 1.0 g/l of catalyst dose.

Malachite green “a cationic dye” and its removal from aqueous solution by adsorption

“…Many treatment technologies have been applied to decolorize MG from aqueous medium, such as biodegradation and decolorization Levin et al 2004;Ren et al 2006;Eichlerová et al 2006;Daneshvar et al 2007a, b;Ayed et al 2008;Ali et al 2009;Wu et al 2009;Cheriaa and Bakhrouf 2009;Ayed et al 2010;Du et al 2011;Khataee et al 2011a, b;Shedbalkar and Jadhav 2011;Hu et al 2011;Abd-El-Kareem and Taha 2012); photocatalytic degradation (Hasnat et al 2003;Kominami et al 2003;Lv et al 2005;Yang et al 2005;Chen et al 2007;Sayılkan et al 2007aSayılkan et al , b, 2008Tayade et al 2007;Wang et al 2008a;Ju et al 2008;Asiltürk et al 2009;Prado and Costa 2009;Bansal et al 2009;Kaneva et al 2010;Liu et al 2010;Bojinova and Dushkin 2011; Maximum wavelength 618 nm Table 2 Applications and toxicity of Malachite green dye…”

Photocatalytic activity of polyaniline-TiO2 nanocomposites

“…Photocatalytic oxidation (degradation) of organic compounds by semiconducting materials such as TiO 2 [2,3], SnO 2 [4], ZrO 2 [5] , ZnO [6], CdS [7], and Fe 2 O 3 [8] has been used for environmental cleaning. Among the various semiconductors, titanium dioxide (TiO 2 ) is the most widely used photocatalyst due to its non-toxicity, high activity, photostability, chemical stability, biological inertness, the good absorption/desorption rate of reactants (especially oxygen) and low cost [2].…”

Synergy effect in the photocatalytic degradation of textile dyeing waste water by using microwave combustion synthesized nickel oxide supported activated carbon

“…The textile industries are creating constant efforts to reduce the COD level, by innumerable methods, such as hydrolysis in a basic medium, chemical processes, membrane filtration, biological treatment, and foam flotation [3][4][5]. Eventhough these methods were inadequate for the highly toxic textile wastewaters [6].the advanced oxidation processes like photocatalysis, Fenton, and photo-Fenton have been employed in the handling of textile wastewater [7][8][9].…”