Photocatalytic Degradation of Anionic Surfactant in Titanium Dioxide Suspension

Abstract

In TiO₂-based photocatalytic degradation of an anionic detergent (lauryl benzenesulfonate) initial pH of 5.0 proved to be most appropriate for high efficiency of surfactant conversion, although lower pHs were more favorable for the adsorption on the surface of the catalyst. A catalyst concentration of 1 g dm⁻³ was optimum for the mineralization of this pollutant. After decreasing the surfactant concentration below the limit of foaming in a closed photo-reactor utilizing H₂O₂ as electron acceptor, total mineralization of the pollutant could be achieved by a longer-time irradiation in a second, air-bubbled reactor. The activity of the photocatalyst proved to be constant even after several reusages. The temperature increase promoted the photoassisted degradation of the anionic detergent in the range of 20–50 °C measured in a home-built pilot equipment. The progress of mineralization became faster only after the conversion of surfactant reached 80–85%. There was found an optimum concentration of the oxidizer, H₂O₂, above which the efficiency of degradation could not be significantly enhanced.