Photocatalytic oxidation of phenol red onto nanocrystalline TiO2 particles

Abstract

The employment of UV/TiO2/O2/H2O2 system for the degradation of phenol red in aqueous solutions using synthesized nanosized TiO2 powder has been investigated in the present study. The anatase TiO2 nanoparticles were synthesized using sol-gel methodology and characterized spectroscopically exploiting SEM, TEM, XRD, and DUR–UV–VIS, in addition to BET analysis. We observe that the degradation of the dye depends on several operational parameters, such as initial pH, catalyst dosage, initial concentration of the dye, UV light intensity, irradiation time, catalyst particle size, and the presence of electron acceptors, such as hydrogen peroxide, besides molecular oxygen. Kinetic analyses indicate that the photodegradation rates of phenol red dye follow the pseudo-first-order kinetics according to the Langmuir–Hinshelwood model. The influence of temperature in the range 25–45 °C was studied. The degradation kinetics were somewhat accelerated by increase in temperature, and apparent activation energy was calculated to be 38.23 kJ mol−1. Thermodynamic parameters, ∆H#, ∆G#, and ∆S# of activation were also computed for the degradation process.