Application of solar light for photocatalytic degradation of Congo red by a floating salicylic acid-modified TiO2/palm trunk photocatalyst

In this study, a highly active, low cost, simple and robust floating photocatalyst based on salicylic acid (SA)-modified TiO2 immobilized on small pieces of palm trunk (PT) as a new porous and light weight support has been studied. These catalysts show the unique feature of floating on the water surface where optimum illumination and oxygenation occurs, leading to a strong increase in their photocatalytic efficiency. XRD, SEM, TGA, FTIR and DRS UV-Vis techniques were used to characterize the TiO2-SA nanocomposite. Photocatalytic tests were carried out under solar irradiation and constrained conditions, i.e. non-stirring and non-oxygenation. The dye Congo red (CR) was used as a probe molecule. The obtained results showed that modification of the surface of TiO2 nanoparticles by SA improved their photocatalytic activity. Particularly, TiO2-SA (50 wt%)/PT was found to be very active whereas the unmodified TiO2 nanoparticles sink to the bottom of the reactor and remain inactive due to the poor illumination and oxygenation. The prepared photocatalysts can be easily recovered, and their photocatalytic activity was found to be sustained after four consecutive runs.