%0 Journal Article
%T Enhanced Photocatalytic Degradation of Methylene Blue Using /MWCNT Composite Synthesized by Hydrothermal Method
%A Sonal Singhal
%A Rimi Sharma
%A Charanjit Singh
%A S. Bansal
%J Indian Journal of Materials Science
%D 2013
%R 10.1155/2013/356025
%X 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¨C6]. Large band gap of ZnS, TiO2, SrTiO3, and Ag3VO4 [7¨C9] 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¨C15] 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
%U http://www.hindawi.com/journals/ijms/2013/356025/