On the other hand, suspensions with methyl orange and the different

TiO2 powders were prepared as described before but they were not subjected to irradiation: in such dark conditions, no changes in the methyl orange concentration were observed for these suspensions all along the test, so absorption to the TiO2 surface was discarded in all cases. Results and discussion FESEM and TEM micrographs in Figure  1 shows the TiO2 Proteasome inhibitor powder as synthesized following the methodology described. It is constituted by spherical particles with a mean size around 1 to 2 μm and formed in turn by the agglomeration of a myriad of smaller nanoparticles. Furthermore, this hierarchical configuration, from now labelled as Tisph powder, displays an outstanding specific surface area, as large as S s = 322 m2 · g-1, indicating the presence of interparticle Selleck ITF2357 porosity (meso- and microporosity). Figure 1 FESEM (a) and TEM (b) micrographs of the Ti sph as-prepared powder. Certainly, such a high specific surface on a micron-sized powder may have tremendous potential for photocatalytic applications, but when going to XRD measurements, no trace of crystalline order was ever observed, see Figure  2a.

This represents a serious problem since as mentioned, a high degree of crystallinity is essential for an efficient photocatalytic performance. In fact, photoreactivity demands a compromise between crystallinity, specific surface and porosity, so here is where we took our amorphous Tisph powder selleck kinase inhibitor to fast microwave crystallization, trying to improve the crystallinity of the TiO2 spheres with the minor loss in specific surface area and porosity (i.e. keeping the hierarchical microstructure).

In this sense, Celecoxib Figure  2 evinces that after 7 min of microwave (MW) radiation, XRD peaks of the TiO2 anatase phase can be already detected in the powder sample. As the exposure time is increased, an increase in the structural order is also observed (narrower peaks) and after 15 min, no further improvement in the crystallinity seems to be attained with the MW treatment. Moreover, the XRD analyses also showed that 10 min under MW radiation produced a crystallinity comparable to that obtained after 1 h at 400°C in a conventional electric furnace (similar width of XRD peaks in diffractograms of Figure  2c and 2f). Figure 2 X-ray diffractograms. Of as-synthesized Tisph powder (curve a) and after 7 min (curve b), 10 min (curve c), 15 min (curve d) and 30 min (curve e) of MW treatment. XRD of the same powder treated at 400°C/1 h in a conventional electric furnace (f). All peaks corresponding to TiO2 anatase (JCPDS file no. 21-1272). When going to the microscope, Figure  3 shows that the spherical morphology is retained after all the heating treatments.