Abstract
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.
Highlights
Styrene is potentially present in food, drinking water, indoor air or the environment as a result of direct releases or leaching of residual monomer from polymers
Several preliminary experiments were performed before initiating the styrene photocatalytic degradation tests
Adsorption tests were carried out in the dark in order to determine the minimum styrene-catalyst contact time that guaranteed adsorption equilibrium at the catalyst surface for each of the pH values used. This test was important to ensure that when initiating the reaction by lamp activation, the disappearance of styrene was due to photocatalytic degradation
Summary
Styrene is potentially present in food, drinking water, indoor air or the environment as a result of direct releases or leaching of residual monomer from polymers. The photocatalytic degradation of styrene in water was investigated using TiO2 as a catalyst. The reactor was charged with 900 mL of styrene solution and TiO2, isolated with the PVC film and operated in the dark (without UV irradiation) during the first 40 min so that the equilibrium adsorption of organic molecules by the catalyst was reached.
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