Ultrasonically Engineered Ceria-Titania Nanostructure Mediated Photocatalytic and Sonocatalytic Degradation of Organic Dye

Research Article

Austin Chem Eng. 2016; 3(3): 1032.

Ultrasonically Engineered Ceria-Titania Nanostructure Mediated Photocatalytic and Sonocatalytic Degradation of Organic Dye

Shah NH1, Bhangaonkar KR1, Pinjari DV2 Mhaske ST1*

1Department of Polymer and Surface Engineering, Institute of Chemical Technology, Matunga, Mumbai, India

2Chemical Engineering Department, Institute of Chemical Technology, Matunga, Mumbai, India

*Corresponding author: Mhaske ST, Department of Polymer and Surface Engineering, Institute of Chemical Technology, Matunga, Mumbai, India

Received: May 04, 2016; Accepted: May 27, 2016; Published: May 30, 2016


CeO2, TiO2 and CeO2/TiO2 composite nanoparticles were synthesized insitu with the use of ultrasound assisted technique. The structural evaluation, its morphology and the corresponding particle size and % weight loss of the synthesized composite nanoparticles were analysed by using X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Thermo Gravimetric Analysis (TGA). Results reveal that XRD patterns have no obvious shift comparing with their standard patterns. Therefore, the oxides of TiO2 and CeO2 should form a composite. Structure characterization of core shell particles by Transmission electron microscopy indicates that the TiO2 shell is around 2nm in thickness and CeO2 core is 8 nm in diameter. The effectiveness of the synthesized catalysts for the Photocatalytic as well as sonocatalytic degradation of Rhodamine B (RhB) dye has also been investigated. It has been observed that the catalytic activity of CeO2 has been effectively increased by coating with a more photoactive TiO2, and that photocatalysis was more efficient than sonocatalysis for the degradation of Rhodamine B.

Keywords: Sonochemical; Anosturctures; CeO2/TiO2; Transmission electron microscopy (TEM); Photocatalytic degradation; Sonocatalytic degradation


Dye components are found in large quantities in the effluent waste from textile, paper, leather, cosmetics industries. The mixing of these dyes with water bodies upon disposal, leads to environmental and health related hazards [1]. Most of the organic dyes are carcinogenic and toxic in nature and hence, Photocatalytic materials that efficiently degrade the dye have been developed by various researches worldwide [2-4]. Combination of two or more materials provides the composite particle with several outstanding physical and chemical performances, especially for metal oxides [3,4]. Cerium oxide, as one of the most activity oxide catalysts in the rare earth oxide series, has the high oxygen storage capacity, redox properties, and metal support interactions [5]. CeO2 is however, generally not considered as photoactive material [6]. Esch et al (2005) research findings about the electron localization of CeO2 with precise observation of highresolution scanning tunneling microscopy reveals that the defects of CeO2 are difficult to move [7]. The results indicate inactive photo properties of CeO2. In work reported earlier by Lin et al (2008) in order to improve activity of CeO2 nanoparticles, CeO2 nanoparticles have been doped with 3d transition metal ions in bulk, but it has not improved remarkably the activity of CeO2 nanoparticles [8]. Titania is a metal oxide that is of interest for coating applications as it is widely known as useful catalyst [9,10]. Previous reports have mostly concentrated on titania coating of silica or alumina particles with diameters ranging from a few hundred nanometers to several micrometers [11,12]. Recently, coating of titania on ceria particles via conventional synthesis route has also been reported [13]. The sonochemical synthesis method is useful in synthesising nanoparticles in short time duration with higher yields. Ultrasound assisted synthesis has proven useful in deposition of nano-scaled metals and metal oxides on ceramic and polymeric particles [14-17]. Extreme reaction conditions of high temperatures of up to 5000°K and pressures up to 500 bar for a short duration in liquids with cooling rates of about 109°K/s can be obtained through the use of ultrasound, which could not possible with the use of other methods [18]. The formation, growth and implosive collapse of bubbles in a liquid medium, results in an instantaneously high temperature and pressure pulse on application of ultrasound in the liquid [19,20]. Unusual and unpredicted morphological changes are induced in the metal oxide particles due to the sound shockwaves and local intense micro mixing. Sonication also facilitates formation of more uniform shells of metal oxides of top of metallic, ceramic or polymeric cores, and is believed to significantly enhance the rate of hydrolysis [21–28]. TiO2 being an important catalyst, we intend to synthesize CeO2/TiO2 composite nanoparticles, where the catalytic activity of CeO2 can be increased by taking cooperative effects from TiO2. Semiconductor mediated photocatalysis has been investigated extensively as a viable.

Technique for the removal of organic and inorganic pollutants from aqueous streams. The technique has proven effective for the oxidative destruction of recalcitrant organic compounds such as dyes [29]. However, photocatalysis has still not gained acceptance as an adequately efficient and effective stand-alone technology for the commercial level decontamination of wastewater [30]. Recently, Ultrasonic (US) irradiation mediated by suitable catalysts (sonocatalysis) has been receiving attention as a promising technique for the treatment of hazardous organic pollutants in wastewater [31-33]. There are few reports on the preparation of individual and core/shell-type CeO2/TiO2 nanoparticles by ultrasound-assisted (US) technique. The present study aims to prepare individual CeO2 and TiO2 as well as CeO2/TiO2 composite nanoparticles. Additionally, it also aims at studying their Photocatalytic and sonocatalytic activity in the degradation of (Rhodamine B) RhB, to evaluate the more effective degradation technique.

Materials and Methods


Titanium Isopropoxide (TTIP) and Cerium Nitrate hexahydrate precursors and propanol solvent were obtained from S. D. Fine Chemicals Ltd., Mumbai, India. Sodium hydroxide was obtained from Merck Ltd., Mumbai, India. Rhodamine B (RhB) dye was procured from Shah Enterprises, Mumbai, India. Deionized water was used for all dilution and sample preparation. All chemical reagents are analytical grade and directly used as purchased, without further purification.

Ultrasound setup

For sonochemical synthesis technique, the ultrasound was generated with the help of a horn type ultrasonic instrument set up. The schematic of the set up is given in Figure 1. The specification and details of the set up, processing parameters used during the experiments are: