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Pugazhenthiran, N., Sathishkumar, P., Albormani, O., Murugesan, S., Kandasamy, M., Selvaraj, M., et al. (2023). Silver nanoparticles modified ZnO nanocatalysts for effective degradation of ceftiofur sodium under UV-vis light illumination. Chemosphere, 313, 137515.
Abstract: Light-induced photocatalytic degradation of ceftiofur sodium (CFS) has been assessed in the presence of plas-monic zinc oxide nanostructures (ZnONSTs), like, ZnO nanoparticles, ZnO nanorods (ZnONRs) and ZnO nano -flowers (ZnONFs). Silver nanoparticles (Ag NPs) loaded ZnO nanostructures (Ag-ZnONSTs) are obtained through seed-assisted chemical reaction followed by chemical reduction of silver. The surface modification of ZnO nanostructures by Ag NPs effectually altered their optical properties. Further, the surface plasmonic effect of Ag NPs facilitates visible light absorption by ZnONSTs and improved the photogenerated electron and hole separation, which makes the ZnONSTs a more active photocatalyst than TiO2 (P25) nanoparticles. Especially, Ag-ZnONRs showed higher CFS oxidation rate constant (k' = 4.6 x 10-4 s-1) when compared to Ag-ZnONFs (k' = 2.8 x 10-4 s-1) and Ag-ZnONPs (k' = 2.5 x 10-4 s-1), owing to their high aspect ratio (60:1). The unidirectional transport of photogenerated charge carriers on the Ag-ZnONRs may be accountable for the observed high photocatalytic oxidation of CFS. The photocatalytic oxidation of CFS mainly proceeds through center dot OH radicals generated on the Ag-ZnONRs surface under light illumination. In addition, heterogeneous activation of perox-ymonosulfate by Ag-ZnONRs accelerates the rate of photocatalytic mineralization of CFS. The quantification of oxidative radicals supports the proposed CFS oxidation mechanism. Stability studies of plasmonic Ag-ZnONSTs strongly suggests that it could be useful to clean large volume of pharmaceutical wastewater under direct solar light irradiation.
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Ashina, C., Pugazhenthiran, N., Sathishkumar, P., Selvaraj, M., Assiri, M. A., Rajasekaran, C., et al. (2023). Ultra-small Ni@NiFe2O4/TiO2 magnetic nanocomposites activated peroxymonosulphate for solar light-driven photocatalytic mineralization of Simazine. J. Environ. Chem. Eng., 11(6), 111342.
Abstract: In the heterogeneous photocatalytic degradation of environmental contaminants the recovery, reuse of employed nanocatalyst was crucial and it is essentially required for the scale up applications. Besides, designing a magnetic material with heterojunction that can effectively oxidize the toxic organic contaminants to non-toxic substance under different reaction conditions including direct solar light irradiation remains a challenge. Considering the above facts, herein, we tailored heterojunction between the magnetic materials and non-magnetic materials with ultra-small Ni nanoparticles modified NiFe2O4/TiO2 nanostructures (Ni@NiFe2O4/TiO2 magnetic nanocomposites) through a simple sonochemical route. The Raman phonons at similar to 540 cm(-1) consistent to nickel metal nanoparticles and the spinel ferrites crystal structure confirmed the formation of Ni@NiFe2O4/TiO2 magnetic nanocomposites. The reduced optical bandgap of the resulting nanocomposites indicated the effective absorption of direct solar light irradiation when compared to the bare TiO2. Thus in-turn, enhanced the photocatalytic efficiency of simazine degradation in the presence of Ni@NiFe2O4/TiO2 magnetic nanocomposites (k= 11.0 x 10(-4) s(-1)) and augmented the activation of peroxymonosulphate (PMS) in the presence of Ni@NiFe2O4/TiO2 magnetic nanocomposites (k= 32.5 x 10(-4) s(-1)). Ni@NiFe2O4/TiO2 +PMS exhibited 3 folds enhanced efficiency in the presence of sunlight. The as-prepared NiFe2O4/TiO2 magnetic nanocatalysts were more stable and the efficiency of simazine oxidation was approximately same for the continuous five cycles at the optimized experimental conditions. The Ni@NiFe2O4/TiO2 magnetic nanocomposites preparation and the activation of PMS may promise the applications in an efficient wastewater treatment.
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