Multiwalled carbon nanotubes (MWCNTs) were synthesized using arc discharge method at a magnetic field of 430？G and purified using HNO3/H2O2. Transmission electron micrographs revealed that MWCNTs had inner and outer diameter of ~2？nm and ~4？nm, respectively. Raman spectroscopy confirmed formation of MWCNTs showing G-band at 1577？cm？1. ZnFe2O4 and ZnFe2O4/MWCNT were produced using one step hydrothermal method. Powder X-ray diffraction (XRD) confirmed the formation of cubic spinel ZnFe2O4 as well as incorporation of MWCNT into ZnFe2O4. Visible light photocatalytic degradation of methylene blue (MB) was studied using pure ZnFe2O4 and ZnFe2O4/MWCNT. The results showed that ZnFe2O4/MWCNT composite had higher photocatalytic activity as compared to pure ZnFe2O4. After irradiation for 5 hours in the visible light, MB was almost 84% degraded in the presence of ZnFe2O4 photocatalyst, while 99% degradation was observed in case of ZnFe2O4/MWCNT composite. This enhancement in the photocatalytic activity of composite may be attributed to the inhibition of recombination of photogenerated charge carriers. 1. Introduction Solar energy active photocatalysts have been a promising material for an environmental purification process. Efforts have been made to synthesize materials capable of utilizing solar spectrum for the photo degradation of industrial waste pollutants and dyes [1]. A wide use of dyes as redox indicators, biological stains, and pharmaceutical industries had adverse effects on gastrointestinal, genitourinary, and cardiovascular system of human body [2, 3]. Degradation of organic pollutants and dyes such as methylene blue, bromophenol blue, and Chicago sky blue from industrial waste water remains as a challenge because of low visible light photo catalytic activity of metal oxides and sulphides [4–6]. Large band gap of ZnS, TiO2, SrTiO3, and Ag3VO4 [7–9] prevents their functioning as effective catalyst for visible light photo degradation [10]. However, the advantage of ferrites as photo catalysts is their capability to absorb visible light solar irradiation because of low band gap and large availability of catalytic sites for adsorption of noxious waste and dyes [11]. Also, ferrites are magnetic [12–15] in nature giving them added advantage of easy recovery after photocatalytic reaction. Albeit, the numerous literature has been reported on the photo degradation of different dyes using ZnFe2O4 as catalyst having spinel structure, where Zn2+ cations occupy tetrahedral site and Fe3+ enters octahedral site [16]. The band gap of ZnFe2O4 is small (1.9？eV) due to
References
[1]
P. Xiong, Y. Fu, L. Wang, and X. Wang, “Multi-walled carbon nanotubes supported nickel ferrite: a magnetically recyclable photocatalyst with high photocatalytic activity on degradation of phenols,” Chemical Engineering Journal, vol. 195-196, pp. 149–157, 2012.
[2]
B. Mokhlesi, J. B. Leikin, P. Murray, and T. C. Corbridge, “Adult toxicology in critical care part II: specific poisonings,” Chest, vol. 123, no. 3, pp. 897–922, 2003.
[3]
J. W. Harvey and A. S. Keitt, “Studies of the efficacy and potential hazards of methylene blue therapy in aniline-induced methaemoglobinaemia,” British Journal of Haematol, vol. 54, pp. 29–41, 1982.
[4]
M. A. Gibson and J. W. Hightower, “Oxidative dehydrogenation of butenes over magnesium ferrite kinetic and mechanistic studies,” Journal of Catalysis, vol. 41, no. 3, pp. 420–430, 1976.
[5]
E. Manova, T. Tsoncheva, D. Paneva, I. Mitov, K. Tenchev, and L. Petrov, “Mechanochemically synthesized nano-dimensional iron-cobalt spinel oxides as catalysts for methanol decomposition,” Applied Catalysis A, vol. 277, no. 1-2, pp. 119–127, 2004.
[6]
P. Baldrian, V. Merhautová, J. Gabriel et al., “Decolorization of synthetic dyes by hydrogen peroxide with heterogeneous catalysis by mixed iron oxides,” Applied Catalysis B, vol. 66, no. 3-4, pp. 258–264, 2006.
[7]
S. Boumaza, A. Boudjemaa, A. Bouguelia, R. Bouarab, and M. Trari, “Visible light induced hydrogen evolution on new hetero-system ZnFe2O4/SrTiO3,” Applied Energy, vol. 87, no. 7, pp. 2230–2236, 2010.
[8]
S. Xu, W. Shangguan, J. Yuan, J. Shi, and M. Chen, “Preparations and photocatalytic degradation of methyl orange in water on magnetically separable Bi12TiO20 supported on nickel ferrite,” Science and Technology of Advanced Materials, vol. 8, no. 1-2, pp. 40–46, 2007.
[9]
Y. Yang, Z. Cao, Y. Jiang, L. Liu, and Y. Sun, “Photoinduced structural transformation of SrFeO3 and Ca2Fe2O5 during photodegradation of methyl orange,” Materials Science and Engineering B, vol. 132, no. 3, pp. 311–314, 2006.
[10]
B. Zhang, J. Zhang, and F. Chen, “Preparation and characterization of magnetic TiO2/ZnFe2O4 photocatalysts by a sol-gel method,” Research on Chemical Intermediates, vol. 34, no. 4, pp. 375–380, 2008.
[11]
S. D. Jadhav, P. P. Hankare, R. P. Patil, and R. Sasikala, “Effect of sintering on photocatalytic degradation of methyl orange using zinc ferrite,” Materials Letters, vol. 65, no. 2, pp. 371–373, 2011.
[12]
X. Liu and W. Gao, “Preparation and magnetic properties of NiFe2O4 nanoparticles by modified pechini method,” Materials and Manufacturing Processes, vol. 27, no. 9, p. 905, 2012.
[13]
M. Drofenik, M. Kristl, D. Makovec, Z. Jagli？i？, and D. Han？el, “Preparation and study of zinc ferrite nanoparticles with a high magnetization,” Materials and Manufacturing Processes, vol. 23, no. 6, pp. 603–606, 2008.
[14]
H. Xu and H. Yang, “Magnetic properties of Y3Fe5O12 nanoparticles doped Bi and Ce ions,” Materials and Manufacturing Processes, vol. 23, no. 1, pp. 1–4, 2008.
[15]
H. Y. He, “Synthesis and magnetic properties of Co0.5Zn0.5Fe2O4 nanoparticles by template-assisted combustion method,” Materials and Manufacturing Processes, vol. 27, no. 9, p. 901, 2012.
[16]
J. P. Singh, G. Dixit, R. C. Srivastava, H. M. Agrawal, V. R. Reddy, and A. Gupta, “Observation of bulk like magnetic ordering below the blocking temperature in nanosized zinc ferrite,” Journal of Magnetism and Magnetic Materials, vol. 324, no. 16, pp. 2553–2559, 2012.
[17]
X. Li, Y. Hou, Q. Zhao, W. Teng, X. Hu, and G. Chen, “Capability of novel ZnFe2O4 nanotube arrays for visible-light induced degradation of 4-chlorophenol,” Chemosphere, vol. 82, no. 4, pp. 581–586, 2011.
[18]
G. Fan, Z. Gu, L. Yang, and F. Li, “Nanocrystalline zinc ferrite photocatalysts formed using the colloid mill and hydrothermal technique,” Chemical Engineering Journal, vol. 155, no. 1-2, pp. 534–541, 2009.
[19]
M. Su, C. He, V. K. Sharmab, et al., “Mesoporous zinc ferrite: synthesis, characterization, and photocatalytic activity with H2O2/visible light,” Journal of Hazardous Materials, vol. 211-212, pp. 95–103, 2012.
[20]
X. Li, Y. Hou, Q. Zhao, and L. Wang, “A general, one-step and template-free synthesis of sphere-like zinc ferrite nanostructures with enhanced photocatalytic activity for dye degradation,” Journal of Colloid and Interface Science, vol. 358, no. 1, pp. 102–108, 2011.
[21]
J. Salvetat, A. J. Kulik, J. Bonard et al., “Elastic modulus of ordered and disordered multiwalled carbon nanotubes,” Advanced Materials, vol. 11, no. 2, pp. 161–165, 1999.
[22]
W. Oh and M. Chen, “Synthesis and characterization of CNT/TiO2 composites thermally derived from MWCNT and titanium(IV) n-butoxide,” Bulletin of the Korean Chemical Society, vol. 29, no. 1, pp. 159–164, 2008.
[23]
X. Wang, Z. Zhao, J. Qu, Z. Wang, and J. Qiu, “Fabrication and characterization of magnetic Fe3O4-CNT composites,” Journal of Physics and Chemistry of Solids, vol. 71, no. 4, pp. 673–676, 2010.
[24]
E. W. Wong, P. E. Sheehan, and C. M. Lieber, “Nanobeam mechanics: elasticity, strength, and toughness of nanorods and nanotubes,” Science, vol. 277, no. 5334, pp. 1971–1975, 1997.
[25]
W. Wang, P. Serp, P. Kalck, and J. L. Faria, “Visible light photodegradation of phenol on MWNT-TiO2 composite catalysts prepared by a modified sol-gel method,” Journal of Molecular Catalysis A, vol. 235, no. 1-2, pp. 194–199, 2005.
[26]
Y. Feng, H. Zhang, Y. Hou et al., “Room temperature purification of few-walled carbon nanotubes with high yield,” ACS Nano, vol. 2, no. 8, pp. 1634–1638, 2008.
[27]
J. Chandradass, D. S. Bae, M. Balasubramanian, and K. H. Kim, “The influence of oleic acid to metal nitrate ratio on the particle size and magnetic properties of lanthanum ferrite nanoparticles by emulsion method,” Materials and Manufacturing Processes, vol. 26, no. 2, pp. 230–235, 2011.
[28]
L. J. Berchmans, V. Leena, K. Amalajyothi, S. Angappan, and A. Visuvasam, “Preparation of lanthanum ferrite substituted with MG and CA,” Materials and Manufacturing Processes, vol. 24, no. 5, pp. 546–549, 2009.
[29]
G. Chandrasekaran, “Spectroscopic study of autocombustion process in the synthesis of nano particles of Ni-Cu ferrite,” Materials and Manufacturing Processes, vol. 22, no. 3, pp. 366–369, 2007.
[30]
Y. H. Guu, K. Tsai, and L. Chen, “An experimental study on electrical discharge machining of manganese-zinc ferrite magnetic material,” Materials and Manufacturing Processes, vol. 22, no. 1, pp. 66–70, 2007.
[31]
H. Jiang, X. Wang, C. Yu, and L. Wang, “Molten salt synthesis of Ni0.5Zn0.5Fe2O4 powders,” Materials and Manufacturing Processes, vol. 25, no. 12, pp. 1489–1493, 2010.
[32]
N. Y. Mostafa, Z. I. Zaki, and Z. K. Heiba, “Structural and magnetic properties of cadmium substituted manganese ferrites prepared by hydrothermal route,” Journal of Magnetism and Magnetic Materials, vol. 329, pp. 71–76, 2013.
[33]
A. C. Ferrari, “Raman spectroscopy of graphene and graphite: disorder, electron-phonon coupling, doping and nonadiabatic effects,” Solid State Communications, vol. 143, no. 1-2, pp. 47–57, 2007.
[34]
J. Maultzsch, S. Reich, C. Thomsen et al., “Raman characterization of boron-doped multiwalled carbon nanotubes,” Applied Physics Letters, vol. 81, no. 14, pp. 2647–2649, 2002.
[35]
M. C. Schabel and J. L. Martins, “Energetics of interplanar binding in graphite,” Physical Review B, vol. 46, no. 11, pp. 7185–7188, 1992.
[36]
A. K. M. Akther Hossain and M. L. Rahman, “Enhancement of microstructure and initial permeability due to Cu substitution in Ni0.50-xCuxZn0.50Fe2O4 ferrites,” Journal of Magnetism and Magnetic Materials, vol. 323, no. 15, pp. 1954–1962, 2011.
[37]
M. M. Rashad, R. M. Mohamed, M. A. Ibrahim, L. F. M. Ismail, and E. A. Abdel-Aal, “Magnetic and catalytic properties of cubic copper ferrite nanopowders synthesized from secondary resources,” Advanced Powder Technology, vol. 23, no. 3, pp. 315–323, 2012.
