Photocatalytic conversion of gaseous ethylbenzene on lanthanum-doped titanium dioxide nanotubes.

The photocatalytic properties of titanium dioxide (TiO₂) make it an attractive material for environmental remediation. In the present study, lanthanum (La(3+))-doped TiO2 nanotubes with excellent photocatalytic activity were fabricated by a combination of sol-gel method and hydrothermal technique. The optimal preparation parameters were determined by the structural characterization using a range of methods and the photocatalytic degradation of gaseous ethylbenzene (EB). Compared with pure TiO₂ nanoparticles, 1.2%-La(3+)-doped - titania nanotubes (1.2%-La(3+)-TNTs) exhibited higher activity under 254 nm UV for conversion of EB. The initial EB concentrations and relative humidity (RH) obviously influenced the photocatalytic activity of 1.2%-La(3+)-TNTs. Kinetic analysis showed that surface adsorption and surface reaction controlled the rate-determining step for RH of 40-50% and >80%, respectively. Gas chromatography and mass spectrometry were used to analyze the intermediates generated in the conversion of EB, allowing a tentative decomposition pathway to be proposed. The prepared photocatalyst exhibited enhanced EB conversion compared with undoped TiO₂, and showed a promise for the decomposition of recalcitrant compounds before subsequent biopurification.