Synthesis and structural characterization of TiO2 and V2O5/TiO2 nanoparticles assembled by the anionic surfactant sodium dodecyl sulfate

Nanostructured titanium dioxide and vanadium oxide supported over titanium dioxide was synthesized using a template synthesis route method under hydrothermal conditions (at 353 K for 5 days) via sodium dodecyl sulfate surfactant. The influence of pH (2.0–9.0) and thermal treatment (623 and 773 K) on the structural, surface acidity and textural properties of TiO2 and V2O5/TiO2 materials was investigated using XRD, thermal analyses, SEM, FTIR, N2 adsorption and pyridine-FTIR measurements. The synthesized TiO2 and V2O5/TiO2 showed high mesoporosities with different pore sizes ranging from 24.6 to 40.6 Å and exhibited nano-sized crystals varying from 7.5 to 15.1 nm. All templated samples exhibited very high surface areas; commencing from 263 to 465 m2/g, as well as pore volume up to 0.73 cm3/g. The synthesized samples exhibited a pure anatase crystalline phase for TiO2 in the pH range 4.8–9, in which substantial amounts of mesopores were developed where that prepared at pH = 2.0 showed the formation of only rutile phase with higher affinity to micropores. Surface acid strength was greater for highly dispersed V containing TiO2 due to a strong interaction of the VOx species with support centers that act as electron attractor centers creating Lewis acid sites. It was found that pH has a paramount effect influencing both the nature of pores and the type of TiO2 formed. The photocatalytic reduction of Hg2+ in water by UV irradiation was chosen to evaluate the activities of the synthesized materials.