Enhanced photocatalytic degradation of the herbicide 2,4-dichlorophenoxyacetic acid by Pt/TiO2–SiO2 nanocomposites

Abstract

In the present work, we report the effect of the addition of platinum (Pt loading 1 wt%) on photocatalysts based on TiO2 and its incorporation in a SiO2 matrix using the sol gel method. The photocatalyst/silica matrix ratio was w(TiO2)/w(SiO2) of 15/85. The characterization of the samples was carried out with X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), specific surface area by N2 physisorption (BET) and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). The photoactivity of the samples was evaluated in the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D). The production of hydroxyl radicals (•OH) on the surface of the samples irradiated with UV light was detected by the fluorescence technique using terephthalic acid as a test molecule. The resulting supported catalyst showed enhanced photocatalytic activity towards 2,4-D degradation, almost 97% of the 2, 4-D was degraded with Pt/TiM–Si sample in 180 min compared to pure commercial TiO2 P25 under UV radiation. The increase in photoactivity can be attributed to the extended band gap energy, large surface area, and a better charge separation and more efficient transfer of the photogenerated charges (e−–h+) due to the presence of Pt ions on the surface of the photocatalyst. Finally, stability and reusability test of the samples was estimated using recycling experiments, indicating its remarkable efficiency in contaminated water treatment.