Mesoporous anatase TiO2 nanoparticles can be synthesized by different routes. In this work, titania nanoparticles were prepared by an eco-friendly, simple, and fast-effective method [1], using titanium butoxide as a precursor and eucalyptus leaf extract solution as a reducing and dispersant agent to avoid the use of hazardous chemicals.
For phase conversion from amorphous TiO2 into crystalline anatase titania, the amorphous TiO2 gels obtained after hydrolysis of precursor were soaked in water at elevated temperature for a prolonged time. This is an alternative process to the conventional calcination methods, which cause irreversible collapse of the porous structure during thermal treatment and drastically decrease the surface area [2, 3]. This is confirmed by BET analysis (the surface area of TiO2 nanoparticles calcined at 500°C is 5.0646 m²/g).
The aim of our work is the preparation of porous TiO2 with both a large surface area and enhanced crystallinity, and the evaluation of photocatalytic activity for the degradation of methylene blue as a model organic dye under UV irradiation (365 nm).
The crystalline nature and structural formation of titanium dioxide NPs biosynthesized were confirmed by the X-ray diffraction technique, and functional groups of TiO2 materials were confirmed by FT-IR spectroscopy [4, 5].
The results revealed that the biosynthesized material, treated in water at 90°C for 24 hours, exhibited an enhanced rate of photocatalytic degradation of the toxic dye (MB). A comparative study with biosynthesized TiO2 calcined at 500°C and commercial TiO2 was carried out for the oxidation of MB under UV (365 nm).
Heat treatment in water could be used as a simple, mild, yet effective method to transform sol-gel derived amorphous TiO2 nanostructures into a porous anatase phase with high surface area and controllable crystallinity.
