Photocatalytic degradation of 4-chlorophenol by titanium dioxide: role of annealing temperature and morphology

Abstract

This work investigates the degradation rate of 4-cholorophenol using Titanium dioxide photocatalysts. Chlorophenols and their compounds are a nuisance as they are recalcitrant to degradation in the environment. Three morphologically different Titanium dioxide catalysts, A, B and C, were immobilized on microscopic glass at a layer of 0.5 mg/cm² and annealed between 500-700°C. The three different TiO₂ powders were characterized using Scanning Electron Microscopy, X-Ray Diffraction and Brunauer Emmett Teller to determine their specific surface area, crystalline and particle sizes. A four–position photocatalytic reactor illuminated by two Ultra violet lamps of wavelength range 320-400 nm and intensity I = 27.87 mW/m² was used to degrade the 4-Chlorophenol in 2 hrs. Aliquots of the degraded 4- chlorophenol were drawn every 30 minutes and analyzed using UV-Vis spectroscopy at λ=226 nm. The optimum annealing temperature of all TiO₂ was found to be 650°C, with type B of hexagonal morphological structure and particle size of 28±2nm having the highest 4-chlorophenol degradation rate, of 71.21%.

Keywords: Photocatalytic, 4-chlorophenol, annealing, morphology