Degradation of 2,6-dichlorophenol by Fe-doped TiO2 Sonophotocatalytic process: kinetic study, intermediate product, degradation pathway

TiO2 and Fe-doped TiO2 nanoparticles were synthesised by sol-gel method. To determine the properties of nanoparticles, scanning electron microscopy, X-ray diffraction and diffuse reflectance spectroscopy were used. The results of the analysis showed that the synthesised nanoparticles are almost uniform and agglomerated as well as the Fe-TiO2 band gap has decreased from 3.1 to 2.84 and the absorption spectrum has changed towards the visible region. The final concentration of 2,6-dichlorophenol and degradation products were measured with gas chromatography-flame ionisation detector and gas chromatography-mass spectrometry. The maximum efficiency and reaction rate constant of 2,6-dichlorophenol were determined at pH 4 and k(0) = 2.11 x 10(-2), initial concentration of 2,6-dichlorophenol 20 mg L-1 and k(0) = 8.01*10(-2), and nanoparticles dosage of 500 mgL(-1) and k(0) = 5.07*10(-2) at 90 min time. The degradation reaction followed the first-order kinetic model. The efficiency of degradation and mineralisation of 2,6-dichlorophenol were in order of sonophotocatalytic > photocatalytic > sonocatalytic.