Styrene photocatalytic degradation reaction kinetics

The aqueous styrene photocatalytic degradation reaction was evaluated using TiO2 P-25 (Degussa) as a catalyst. These experiments were accomplished in a batch slurry reactor with temperature control and a UV lamp. The effects of the initial styrene concentration, the catalyst concentration, the hydrogen peroxide addition and the initial pH of the solution on the reaction were evaluated. The experimental results showed that in 90 min, 95% of the initial styrene was degraded by photocatalysis. It was verified that the styrene degradation rate fits a pseudo-first-order kinetics for initial styrene concentrations between 15.27 and 57.25 ppm, at 30ºC. The chromatographic analysis of the samples collected during the photocatalytic degradation revealed benzaldehyde as one of the intermediates. The addition of H2O2 accelerated the degradation reaction until the system reached a certain optimum peroxide concentration in the reactor. Further H2O2 additions resulted in a reaction rate reduction.