Catalytic Reclamation of Silver Present in Photographic Waste Using Magnetically Separable TiO2@CuFe2O4 Nanocomposites and Thereof Its Use in Antibacterial Activity

Vrushali B Shevale; Ananta G Dhodamani; Sagar D Delekar

doi:10.1021/acsomega.9b03260

Catalytic Reclamation of Silver Present in Photographic Waste Using Magnetically Separable TiO₂@CuFe₂O₄ Nanocomposites and Thereof Its Use in Antibacterial Activity

ACS Omega. 2020 Jan 6;5(2):1098-1108. doi: 10.1021/acsomega.9b03260. eCollection 2020 Jan 21.

Authors

Vrushali B Shevale¹, Ananta G Dhodamani¹, Sagar D Delekar¹

Affiliation

¹ Department of Chemistry, Shivaji University, Kolhapur 416 004, Maharashtra, India.

Abstract

In the present investigation, the silver present in photographic waste is reclaimed catalytically using magnetically separable TiO₂@CuFe₂O₄ nanocomposites (NCs), and further, the recovered silver nanoparticles [Ag(0) NPs] are tested against the representative bacteria for the antibacterial activity. Initially, a series of the different composites between TiO₂ nanoparticles and CuFe₂O₄ nanoparticles are synthesized by a sol-gel "ex situ" method to enhance the catalytic activity of bare nanomaterials toward the visible region of the electromagnetic spectrum. X-ray diffraction reveals the presence of characteristic patterns for the tetragonal structure in the bare materials or TiO₂@CuFe₂O₄ NCs; however, the dominance in the phase as well as intensity of the respective XRD reflections in the NCs is observed according to the content of TiO₂ or CuFe₂O₄ in the NCs. Field-emission electron microscopic images show the uniform spherical particles for the representative TiO₂@CuFe₂O₄ NCs, which is also confirmed through the HRTEM images. The magnetically separable behavior of the representative TiO₂@CuFe₂O₄ NCs is confirmed through the VSM measurements, which also shows the superparamagnetic properties due to the S-shaped nature of the hysteresis loop. Thereafter, a photoconversion reaction of Ag(I) ions to Ag(0) NPs as a model reaction is carried out using the different TiO₂@CuFe₂O₄ NCs under visible light irradiation, and hence, the higher catalytic recovery of Ag(0) NPs is observed for a composite containing 10 wt % TiO₂ and 90 wt % CuFe₂O₄ than that of other NCs or the bare one alone. The optimized protocol of the model reaction is adopted for reclaiming Ag(0) NPs from photographic waste. The progress of the catalytic reclamation reaction is monitored using UV-visible, and then sizes of the recovered Ag(0) NPs are confirmed through the HRTEM images. Thereafter, the recovered Ag(0) NPs are tested for complete photoinactivation of Escherichia coli bacteria within 120 min.