The styrene photocatalytic degradation reaction

In this study the aqueous styrene photocatalytic degradation reaction was evaluated using TiO 2 P-25 (Degussa) as catalyst. The experiments were accomplished in a batch reactor, with temperature control and catalyst in suspension. The radiation source was a 28 W UV lamp. Determinations of styrene concentrations were done by gas chromatography with a flame ionization detector (FID). Preliminary tests were made to determine the necessary contact time to reach the adsorption equilibrium. Besides, seeking to separate the photolysis of the photocatalysis, experiments were made in which the solution was irradiated with and without TiO 2 and also in the presence of TiO2 but without irradiation. Then the effects of the styrene initial concentration were evaluated, as well as, the catalyst concentration, the hydrogen peroxide addition and the initial pH of the solution. The experimental results showed that styrene can be degraded by photocatalysis and, in 90 min, 95 % of degradation was achieved. It was verified that the styrene degradation rate can be approached by a pseudo-first-order kinetics for styrene initial concentrations from 15.27 to 57.25 ppm, at 30°C. Besides, the addition of H2O2 accelerates the degradation reaction until it reaches a certain optimum peroxide concentration in the reactor. Further H2O2 additions resulted in reaction rate reduction.