Use of halloysite–TiO2 nanocomposites for the decomposition of tebuconazole fungicide in water

In this study we present halloysite clay mineral combined with TiO2, as promising new class of nanomaterials that can be used as an effective, cost-efficient, and environment-friendly procedure for the decomposition of tebuconazole, C16H22ClN3O, [(RS)-1-p-chlorophenyl-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)-pentan-3-ol], TEB-fungicide, in water. For this purpose, halloysite–TiO2 nanoparticles are prepared using the sol-gel methodology combined with hydrothermal treatment of the samples in mild conditions. The halloysite–TiO2 nanocomposites are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N2 sorption–desorption isotherms analysis by Brunauer–Emmett–Teller to determine specific surface area (SSA). The total pore volume of the halloysite 40%–TiO2 60% prepared nanocomposite and its SSA are 0.35 cm3/g and 188 m2/g, respectively. This nanocomposite showed a photocatalytic efficiency of 39.5% to TEB decomposition after 240 min under UV irradiation. The halloysite 30%–TiO2 70% nanocomposite has a total pore volume of 0.34 cm3/g and a SSA of 187 m2/g. This nanomaterial shows 40.0% photocatalytic efficiency for TEB destruction under UV exposure. The best photodegradation efficiency, 47.4% of TEB was achieved with the halloysite 10%–TiO2 90% nanomaterial, instead of 33.2% decomposition efficiency measured when commercial TiO2 (Degussa P25) was used. In this case, the halloysite 10%– TiO2 90% nanocomposite showed the highest SSA of 222 m2/g. The concentration of TEB did not show any significant change in all the samples after 150 min exposure under UV illumination.