FeOx magnetization enhancing E. coli inactivation by orders of magnitude on Ag-TiO2 nanotubes under sunlight

Abstract

a b s t r a c tDrastic bacterial enhancement was observed when the Ag(3%)-TiO 2 nanotubes were modified with FeOx (3%) magnetic oxide. On bare TiO 2 -nanotubes a reduction of 0.2log 10 CFU was observed within one hour under simulated low intensity solar light. Under similar conditions, a bacterial reduction of 2.5log 10 CFU was observed on Ag(3%)TiO 2 increasing to 6.0log 10 CFU on Ag(3%)-TiO 2 -FeOx(3%) magnetic nanotubes. The bacterial inactivation kinetics is strongly influenced by the addition of FeOx. The fast inactivation induced by the composite catalyst seems to involve an increase in the interfacial charge transfer (IFCT) compared to a 2-oxide composite photocatalyst. Stable recycling of the photocatalyst was observed leading to bacterial oxidation. The unambiguous identification of the radical intermediates: OH-radicals, O-singlet and the valence holes vb(h + ) on the Ag-TiO 2 -FeOx interface showed that the valence band holes vb(h + ) were the main oxidative intermediates leading to bacterial inactivation. Nanotubes size, crystallinity and bulk composition of magnetite 1% ( = 51.0• ), anatase 5% ( = 8.9• ), goethite 37.3% ( = 9.0 • ), silver 1% ( = 2.7• ) was obtained by the Rietveld refinement for the Ag(3%)-TiO 2 -FeOx(3%) nanotubes. The redox chemistry during bacterial inactivation was determined by X-ray photoelectron spectroscopy (XPS).

Pure and Fe-Doped Mesoporous Titania Catalyse the Oxidation of Acid Orange 7 by H2O2 under Different Illumination Conditions: Fe Doping Improves Photocatalytic Activity under Simulated Solar Light

“…Indeed, the catalyst prepared by direct synthesis showed the best performance under solar illumination, i.e., under experimental conditions that could be useful for future applications in water remediation, where solar light could be exploited to abate the costs of UV irradiation. Addition of a magnetic phase, as reported in the literature [64], could render this kind of materials even more attractive for practical usage, also guaranteeing a facile separation of the solids after their use.…”

Bacterial adhesion and inactivation on Ag decorated TiO2-nanotubes under visible light: Effect of the nanotubes geometry on the photocatalytic activity

“…With respect to the photocatalytic activity of the polymorphs, although it is somewhat controversial, the anatase phase is generally regarded as being more active than rutile [17,18]. An emerging field of interest in photocatalysis is the development of TiO2 nanotubes (TiO2-NTs) and their coupling with cations, metal-oxides and additional composites leading to a higher nanocomposite sensitization in the visible range [19][20][21]. Titanium anodization is a simple preparation leading to controllable nanotubes formation, chemical resistivity, high surface area (2-3 orders of magnitude higher than a flat surface) and therefore high loading capability.…”

Synthesis of Ag‐modified TiO2 nanotube and its application in photocatalytic degradation of dyes and elemental mercury

“…used AgNO 3 as an Ag doped precursor to manufacture TiO 2 nanocomposite thin films. Mangayayam et al . synthesized Ag‐TiO 2 ‐FeO x nanotubes by using Degussa P‐25 TiO 2 as a precursor, and then Ag + was subsequently reduced with sodium borohydride (NaBH 4 ).…”

“…11,[16][17][18][19][20] Kumar et al 17 used AgNO 3 as an Ag doped precursor to manufacture TiO 2 nanocomposite thin films. Mangayayam et al 21 synthesized Ag-TiO 2 -FeO x nanotubes by using Degussa P-25 TiO 2 as a precursor, and then Ag + was subsequently reduced with sodium borohydride (NaBH 4 ). The resulting powders were calcined at 500 ∘ C for 1 h. Liang et al 16 fabricated TiO 2 nanotube by anodic oxidation and added AgNO 3 and NaBH 4 to generate Ag + ions.…”