Study of the Interaction of Ti-Zn as a Mixed Oxide at Different pH Values Synthesized by the Sol-Gel Method and Its Antibacterial Properties.

TiO 2 , ZnO, and their combination (TiO 2 -ZnO) at different molar ratios and pH values (Ti-Zn A and B 3:1, 1:1, and 1:3) via the sol-gel method were characterized by SEM, XRD, UV-Vis, and FT-IR. Moreover, antibacterial tests of the nanoparticles were conducted against Escherichia coli ( E. coli ), Salmonella paratyphi ( S. paratyphi ), Staphylococcus aureus ( S. aureus ), and Listeria monocytogenes ( L. monocytogenes ). The indirect bandgap of the Ti-Zn binary oxide synthesized in the basic process at molar ratios of 3:1, 1:1, and 1:3 exhibited a higher eV (3.31, 3.30, and 3.19 eV, respectively) compared to pure TiO 2 (3.2 eV) and synthesized in the acid process (3.22, 3.29, and 3.19 eV at same molar ratio, respectively); in addition, the results of the indirect bandgap were interesting due to a difference found by other authors. Moreover, the sol-gel method promoted the formation of a spherical, semi-sphere, and semi-hexagonal shape (TiO 2 , Ti-Zn 1:1, and Ti-Zn 1:3) with a size ≤ 150 nm synthesized during the acid process, with a crystallite size of ~71, ~12, ~34, and ~21 nm, respectively, while ZnO NPs developed a hexagonal and large size (200-800 nm) under the same synthesis process (acid). Samples were classified as TiO 2 anatase phase (basic synthesis); however, the presented changes developed in the rutile phase (24% rutile phase) at an acid pH during the synthesis process. Moreover, Ti-Zn maintained the anatase phase even with a molar ratio of 1:3. The most interesting assessment was the antibacterial test; the Ti-Zn A (1:3) demonstrated a bacteriostatic effect compared with all treatments except ZnO, which showed a similar effect in dark conditions, and only Gram-positive bacteria were susceptible ( Listeria monocytogenes > Staphylococcus aureus ). Therefore, the Ti-Zn characteristic suggests that the results have potential in treating wastewater as well as in pharmaceutical (as drug carriers) and medical applications.