TiO2/ZnO nanocomposites were prepared by the sol-gel method with and without addatives such as carboxy methyl cellulose (CMC), poly(ethylene glycol) (PEG), polyvinylpyrrolidon, (PVP), and hydroxylpropylcellulose (HPC). The characteristics of the prepared TiO2/ZnO nanocomposites were identified by IR spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) methods. The additives have a significant effect on the particle size distribution and photocatalytic activity of TiO2/ZnO nanocomposites. The photocatalytic activity of the synthesized nanocomposites was investigated for decolorization of methyl orange (MO) in water under UV-irradiation in a batch reactor and the results showed that the photocatalytic activity of the nanocomposites have been increased by CMC, PEG, PVP, and HPC, respectively. SEM has shown that the particle size distribution of TiO2/ZnO nanocomposite in the presence of HPC was better than the other samples. 1. Introduction Azo dyes constitute the largest group of coloring materials in the textile industry [1–3]. Release of these substances in nature is the largest source of pollution for natural ecosystems. In recent decades, semiconductor photocatalyst TiO2 has been investigated as one of the most promising candidate for a photocatalyst and it has been attracted due to its potential application in removing of all types of organic pollutants in water [4–6]. In order to improve the photocatalytic activity and the response into visible part of the spectrum, TiO2 doping with metal ions or metal oxides has been applied [1, 2]. Several methods on the preparation of TiO2/ZnO were reported, such as solid-state method, impregnation method, and chemical coprecipitation method [7–9]. Another method is the sol-gel method that has significant advantages such as, high purity, good uniformity of the powder microstructure, low-temperature synthesis, and easily controlled reaction condition and therefore it has been used for preparing of TiO2/ZnO nanocomposite [4, 7, 10–12]. In this work, TiO2/ZnO nanocomposites were prepared by the sol-gel method in presence and absence of CMC, PEG, PVP, and HPC as additives. The synthesized nanocomposites were characterized by means of XRD, SEM, EDS, and IR spectroscopy. Since the particle size is an important parameter in photocatalytic activity, the effects of mentioned additives have been surveyed on the particle size distribution. The photocatalytic activity of TiO2/ZnO nanocomposites were assessed for decolorization of methyl orange (MO) in water under
References
[1]
G. Colón, M. Maicu, M. C. Hidalgo, and J. A. Navío, “Cu-doped TiO2 systems with improved photocatalytic activity,” Applied Catalysis B, vol. 67, no. 1-2, pp. 41–51, 2006.
[2]
H. Yu, X. J. Li, S. J. Zheng, and W. Xu, “Photocatalytic activity of TiO2 thin film non-uniformly doped by Ni,” Materials Chemistry and Physics, vol. 97, no. 1, pp. 59–63, 2006.
[3]
P. Aberoomand Azar, S. Moradi Dehaghi, S. Samadi, S. Kamyar, and M. Saber Tehrani, “Effect of Nd3+, pectin and poly(ethylene glycol) on the photocatalytic activity of TiO2/SiO2 film,” Asian Journal of Chemistry, vol. 22, pp. 1619–1627, 2010.
[4]
J. Tian, L. Chen, J. Dai, X. Wang, Y. Yin, and P. Wu, “Preparation and characterization of TiO2, ZnO, and TiO2/ZnO nanofilms via sol-gel process,” Ceramics International, vol. 35, no. 6, pp. 2261–2270, 2009.
[5]
X. T. Wang, S. H. Zhong, and X. F. Xiao, “Photo-catalysis of ethane and carbon dioxide to produce hydrocarbon oxygenates over ZnO-TiO2/SiO2 catalyst,” Journal of Molecular Catalysis A, vol. 229, no. 1-2, pp. 87–93, 2005.
[6]
M. H. Liao, C. H. Hsu, and D. H. Chen, “Preparation and properties of amorphous titania-coated zinc oxide nanoparticles,” Journal of Solid State Chemistry, vol. 179, no. 7, pp. 2020–2026, 2006.
[7]
D. L. Liao, C. A. Badour, and B. Q. Liao, “Preparation of nanosized TiO2/ZnO composite catalyst and its photocatalytic activity for degradation of methyl orange,” Journal of Photochemistry and Photobiology A, vol. 194, no. 1, pp. 11–19, 2008.
[8]
J. Tian, L. Chen, Y. Yin et al., “Photocatalyst of TiO2/ZnO nano composite film: preparation, characterization, and photodegradation activity of methyl orange,” Surface and Coatings Technology, vol. 204, no. 1-2, pp. 205–214, 2009.
[9]
K. Karthik, S. K. Pandian, and N. V. Jaya, “Effect of nickel doping on structural, optical and electrical properties of TiO2 nanoparticles by sol-gel method,” Applied Surface Science, vol. 256, no. 22, pp. 6829–6833, 2010.
[10]
J. Wang, J. Li, Y. Xie et al., “Investigation on solar photocatalytic degradation of various dyes in the presence of Er3+ : YAlO3/ZnO-TiO2 composite,” Journal of Environmental Management, vol. 91, no. 3, pp. 677–684, 2010.
[11]
C. Chen, Z. Wang, S. Ruan, B. Zou, M. Zhao, and F. Wu, “Photocatalytic degradation of C.I. Acid Orange 52 in the presence of Zn-doped TiO2 prepared by a stearic acid gel method,” Dyes and Pigments, vol. 77, no. 1, pp. 204–209, 2008.
[12]
Z. Zhang, Y. Yuan, Y. Fang, L. Liang, H. Ding, and L. Jin, “Preparation of photocatalytic nano-ZnO/TiO2 film and application for determination of chemical oxygen demand,” Talanta, vol. 73, no. 3, pp. 523–528, 2007.
[13]
Z. Liu, Z. Jin, W. Li, and J. Qiu, “Preparation of ZnO porous thin films by sol-gel method using PEG template,” Materials Letters, vol. 59, no. 28, pp. 3620–3625, 2005.
[14]
C. Hariharan, “Photocatalytic degradation of organic contaminants in water by ZnO nanoparticles: revisited,” Applied Catalysis A, vol. 304, no. 1-2, pp. 55–61, 2006.
[15]
Y. Jiang, M. Wu, X. Wu, Y. Sun, and H. Yin, “Low-temperature hydrothermal synthesis of flower-like ZnO microstructure and nanorod array on nanoporous TiO2 film,” Materials Letters, vol. 63, no. 2, pp. 275–278, 2009.
[16]
S. Janitabar-Darzi and A. R. Mahjoub, “Investigation of phase transformations and photocatalytic properties of sol-gel prepared nanostructured ZnO/TiO2 composites,” Journal of Alloys and Compounds, vol. 486, no. 1-2, pp. 805–808, 2009.
[17]
S. Rengaraj, S. Venkataraj, J. W. Yeon, Y. Kim, X. Z. Li, and G. K. H. Pang, “Preparation, characterization and application of Nd-TiO2 photocatalyst for the reduction of Cr(VI) under UV light illumination,” Applied Catalysis B, vol. 77, no. 1-2, pp. 157–165, 2007.
[18]
Z. Zhang, Y. Yuan, L. Liang, Y. Cheng, G. Shi, and L. Jin, “Preparation and photoelectrocatalytic activity of ZnO nanorods embedded in highly ordered TiO2 nanotube arrays electrode for azo dye degradation,” Journal of Hazardous Materials, vol. 158, no. 2-3, pp. 517–522, 2008.
[19]
A. Abdel Aal, M. A. Barakat, and R. M. Mohamed, “Electrophoreted Zn-TiO2-ZnO nanocomposite coating films for photocatalytic degradation of 2-chlorophenol,” Applied Surface Science, vol. 254, no. 15, pp. 4577–4583, 2008.
[20]
C. C. Chan, C. C. Chang, W. C. Hsu, S. K. Wang, and J. Lin, “Photocatalytic activities of Pd-loaded mesoporous TiO2 thin films,” Chemical Engineering Journal, vol. 152, no. 2-3, pp. 492–497, 2009.
[21]
J. Chen, N. Yao, R. Wang, and J. Zhang, “Hydrogenation of chloronitrobenzene to chloroaniline over Ni/TiO2 catalysts prepared by sol-gel method,” Chemical Engineering Journal, vol. 148, no. 1, pp. 164–172, 2009.
[22]
B. A. Sava, A. Diaconu, M. Elisa, C. E. A. Grigorescu, I. C. Vasiliu, and A. Manea, “Structural characterization of the sol-gel oxide powders from the ZnO-TiO2-SiO2 system,” Superlattices and Microstructures, vol. 42, no. 1–6, pp. 314–321, 2007.
[23]
S. Liao, H. Donggen, D. Yu, Y. Su, and G. Yuan, “Preparation and characterization of ZnO/TiO2, SO4？2-/ZnO/TiO2 photocatalyst and their photocatalysis,” Journal of Photochemistry and Photobiology A, vol. 168, no. 1-2, pp. 7–13, 2004.
[24]
M. D. Snel, F. Snijkers, J. Luyten, A. Kodentsov, and G. de With, “Tape casting and reaction sintering of titanium-titanium oxide-nickel oxide mixtures,” Journal of the European Ceramic Society, vol. 28, no. 6, pp. 1185–1190, 2008.
[25]
J. Qiu, Z. Jin, Z. Liu et al., “Fabrication of TiO2 nanotube film by well-aligned ZnO nanorod array film and sol-gel process,” Thin Solid Films, vol. 515, no. 5, pp. 2897–2902, 2007.
