Well-dispersed titanium dioxide and silver nanoparticles on external and internal surfaces of asymmetric alumina hollow fibers for enhanced chromium (VI) photoreductions

Abstract

Silver (Ag)-decorated titanium dioxide (TiO 2 ) catalysts were produced under ultrasound irradiation at different loadings of Ag nanoparticles (from 5 to 50 wt%). Then, the catalysts were supported on internal and external surfaces of alumina hollow bers with asymmetric pore size distribution. The produced catalysts were considered for Cr(VI) photoreductions. The ultrasound-assisted process potentialized the distribution of Ag nanoparticles on the TiO 2 surface. The loading of Ag nanoparticles at concentrations greater than 5 wt% was necessary to improve the TiO 2 activity for Cr(VI) photoreduction. The loading of Ag nanoparticles at 30 wt% improved the Cr(VI) photoreduction of the single TiO 2 catalyst from 40.49 ± 0.98 to 55.00 ± 0.83% after 180 min of reaction. Suspended and supported Ag-decorated TiO 2 catalysts achieved total Cr(VI) photoreduction after 21 h of reaction. The adjusted reaction rate constant with the externally supported Ag-TiO 2 catalyst was 3.57x10 -3 ± 0.18 x10 -3 min -1 . Similar reaction rate constants were achieved with suspended and internally supported catalysts (approximately 2.70x10 -3 min -1 ). After 10 sequential reuses, all catalysts presented similar Cr(VI) photoreductions of approximately 66%.Nevertheless, the use of the externally supported catalyst is suggested for Cr(VI) photoreductions due to its superior catalyst activity at least in the rst reuse cycles. HighlightsProduction and decoration of Ag nanoparticles on TiO 2 by ultrasound irradiation Cr(VI) photoreduction is favored by the increase in Ag nanoparticle loading Supporting of Ag-decorated TiO2 catalysts on alumina hollow bers Externally supported catalysts presented superior reaction rate for Cr(VI) reduction

Estimation and photocatalytic reduction of toxic chromium metal ions from environmental samples by zinc-based nanocomposite

“…20 However, the activity of the single metal oxide is limited by the drawbacks of inadequate light capture and facile mixing of the carriers produced by photons. 21 Therefore, coupling the ZnO nanocomposite to increase its photocatalytic activity is necessary for applications in the real world. By coupling ZnO with ZnHCC, the combined material could exhibit the synergistic effects, such as improved charge separation and utilization of a broader range of the solar spectrum, making the photocatalyst more efficient.…”