Abstract
In the present investigation, the silver present in photographic waste is reclaimed catalytically using magnetically separable TiO(2)@CuFe(2)O(4) 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 TiO(2) nanoparticles and CuFe(2)O(4) 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 TiO(2)@CuFe(2)O(4) 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 TiO(2) or CuFe(2)O(4) in the NCs. Field-emission electron microscopic images show the uniform spherical particles for the representative TiO(2)@CuFe(2)O(4) NCs, which is also confirmed through the HRTEM images. The magnetically separable behavior of the representative TiO(2)@CuFe(2)O(4) 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 TiO(2)@CuFe(2)O(4) NCs under visible light irradiation, and hence, the higher catalytic recovery of Ag(0) NPs is observed for a composite containing 10 wt % TiO(2) and 90 wt % CuFe(2)O(4) 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.