Abstract
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 TiO
2 and V
2O
5/TiO
2 materials was investigated using XRD, thermal analyses, SEM, FTIR, N
2 adsorption and pyridine-FTIR measurements. The synthesized TiO
2 and V
2O
5/TiO
2 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
m
2/g, as well as pore volume up to 0.73
cm
3/g. The synthesized samples exhibited a pure anatase crystalline phase for TiO
2 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 TiO
2 due to a strong interaction of the VO
x
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 TiO
2 formed. The photocatalytic reduction of Hg
2+ in water by UV irradiation was chosen to evaluate the activities of the synthesized materials.