Kinetic Study of Sodium Dodecylsulfate Degradation by Solar Heterogeneous Photocatalysis Based on Tungsten Oxide

Sodium Dodecyl Sulfate or SDS is a chemical compound widely used in detergent and cosmetic formulations. This work describes the application of solar heterogeneous photocatalysis based on tungsten oxide (WO3) to the kinetic study of the degradation of sodium dodecylsulfate. The experiments were performed at room temperature to study the effect of the initial catalyst mass. The results showed that a small amount of tungsten oxide is sufficient to degrade sodium dodecyl sulfate. The initial concentrations of SDS varied between 5 and 15 mg.L-1. According to the results, more than 87% reduction is obtained after 120 min of solar irradiation of the SDS solution for a WO3/SDS mass ratio of 1/5. The detailed kinetic analysis of the photodegradation of sodium dodecylsulfate showed that the disappearance of the anionic surfactant follows a pseudo-prime model. According to the Langmuir-Hinshelwood model, the kinetics constant calculated from the linear form of this model are : k = 0.042 mg.L.min-1 and K = 0.060 L.mg-1.