Effect of AC loading and calcination temperature on the photocatalytic activity of nano--TiO2 and TiO2/AC composite prepared via sol gel methods for MCB degradation in water

• Main Author: Nattuwat, Bunsa
• Format: text
• Language: English
• Published: Animo Repository 2010
• Subjects: Carbon, Activated; Titanium dioxide; Chlorobenzene; Photodegradation; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/6059; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=13174&context=etd_masteral
• Institution: De La Salle University

This study investigated the effect of activated carbon (AC) loading and calcination temperature on the surface properties of nano-TiO2 and TiO2/AC composite catalyst and the photodegradation of monochlorobenzene (MCB) in water. Nano-TiO2 and TiO2/AC composite were synthesized via sol gel method with titanium (IV) isopropoxide as the precursor material. For the composite catalysts, activated carbon (AC) loadings of 5%, 10%, and 15% by weight were used and the catalysts were calcined at different calcination temperatures of 300oC, 350oC, and 400oC. The catalysts were tested for their activity through the photodegradation of aqueous MCB solution with an initial concentration of 60ppm. The concentration of MCB was monitored during photodegradation. Samples were analyzed using GC-FID. Characteristics of the catalysts were determined using Thermo-Gravimetric Analyzer (TGA), Transmission Electron Microscopy (TEM), Scanning Electron Microscope and Energy Dispersive X-ray analysis (SEM/EDX), Fourier Transform Infrared spectroscopy (FT-IR), XRD, the Brunauer-Emmett-Teller (BET) Analyzer, the X-Ray Diffraction (XRD), and UV-vis. spectrophotometer. The actual percent weight loss of AC decomposition increased as the amount of AC loading increased (6%, 12%, 21% percent weight loss of AC for the 5%wt, 10%wt, 15%wt AC loading, respectively). The crystallite size range of TiO2/AC composite is 3 to 7nm. As the calcination temperature and AC loading increases, the crystallite size decreases. This can be attributed to the fact that TiO2 crystallites aggregate to form smaller clusters which is more evident upon increasing the calcination temperature. For the SEM results, as the calcination temperature and AC loading were increased, it was observed that TiO2 particles entered and agglomerated into the AC particle pores. The elemental analysis from the EDX revealed only Ti and O on the surface of nano-TiO2 with the addition of C for TiO2/AC composite. The functional groups on the surface were related to the stretching of Ti-OH group. Moreover, the FT-IR results showed that as the calcination temperature was increased the peak bands v of the functional groups became smaller. There was relatively no effect on the peak band of the functions groups upon increasing the AC loading. For the BET results, as the calcination temperature was increased, the surface area increased as well due to the increased porosity of the catalyst. Also as the AC loading increases, the surface area increases because AC has a high surface area. The nano-TiO2 and TiO2/AC composite had a high content of anatase phase. From Scherrer’s equations, it was proven that the average crystallite sizes of nanoTiO2 and TiO2/AC were indeed in nanometer. In accordance with the Planck’s equation, as the calcination temperature was increased, the energy band gap of nanoTiO2 and TiO2/AC composites became closer to 3.20eV. On the other hand, there was no change in the energy band gap when AC was added. Aqueous MCB solution was photocatalytically degradade using the synthesized catalysts. The shortest time it took for the MCB to fully degrade was observed at 80 minutes for the TiO2/AC with 10%wt AC loading and calcination temperature at 350oC. Moreover, MCB degradation was higher when TiO2/AC composite was used compared to bare to nano-TiO2 and Degussa P25.