Simple synthesis of anatase/rutile/brookite TiO2 nanocomposite with superior mineralization potential for photocatalytic degradation of water pollutants

Abstract

In this study, we report a simple synthesis procedure of anatase/rutile/brookite TiO2 nanocomposite material, designed for efficient transformation of emerging water pollutants (e.g., bisphenol (A)) to CO2 and H2O as final products of complete photo-oxidation. Sol–gel procedure with a subsequent hydrothermal treatment carried out at mild temperature and in the presence of 3M HCl led to the formation of TiO2 nanomaterial, which consists of anatase (43%), rutile (24%) and brookite (33%) polymorph phases within the same material. For the purpose of efficient evaluation of nanocomposite activity, individual polymorphs of anatase, rutile and brookite were also prepared using the same precursor material. Individual polymorph phases within the nanocomposite material crystallized separately and formed mixed agglomerates; the polymorphs were regularly shaped and randomly distributed in agglomerates, where some of the anatase particles exhibited truncated octahedron morphology, rutile was in the form of tetragonal prisms with pyramidal termination and brookite was shaped as blocky particles, which were found to be the smallest within the nanocomposite material (∼20nm). Newly synthesized TiO2 nanocomposite was highly active in terms of mineralization, since after 60min of irradiation under UV light almost 60% of water dissolved pollutant bisphenol A was successfully transformed into CO2 in H2O. On the other hand, the benchmark TiO2 P25 Degussa catalyst reached a lower extent of mineralization, which is due to significantly less expressed resistance to accumulation of carbonaceous deposits on the catalyst surface.