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

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.

Removal of Organic Dyes from Water and Wastewater Using Magnetic Ferrite-Based Titanium Oxide and Zinc Oxide Nanocomposites: A Review

“…Several studies have reported the photocatalytic activity of copper ferrite and its nanocomposites in water and wastewater treatment [109,111,112].…”

“…More studies on the activity of copper ferrite nanocomposites for the degradation of organic pollutants are listed in Table 2. Several studies have reported the photocatalytic activity of copper ferrite and its nanocomposites in water and wastewater treatment [109,111,112].…”

Photocatalytic Degradation of Organic Pollutants by Using Nanocrystalline Boron‐doped TiO2 Catalysts

“…Last few decades, several approaches and strategies have been developed to improve the optoelctronic properties of TiO 2 as photocatalyst, which includes doping with metal or non‐metals, formation of composite with other materials, photosensitization and so on [18–21] . On more general grounds, the main purpose of all the studies are to modify TiO 2 to capable it to work in visible light by keeping original network intact [22] .…”

“…[16,17] Last few decades, several approaches and strategies have been developed to improve the optoelctronic properties of TiO 2 as photocatalyst, which includes doping with metal or non-metals, formation of composite with other materials, photosensitization and so on. [18][19][20][21] On more general grounds, the main purpose of all the studies are to modify TiO 2 to capable it to work in visible light by keeping original network intact. [22] Modified TiO 2 with doping is one of the effective way to tune the material properties, without disturbing original structure of TiO 2 with a degree of substitution that goes beyond the doping level appears as a challenging and promising way to tailor its properties, which include metal doping, [23,24] non metal doping [25,26] and self doping.…”

Preparation and performance of CuFe2O4 and ZnFe2O4 magnetic nanocrystals

“…The spinel ferrites of AB 2 O 4 have great application in the supercapacitors [1,2], photocatalysis [3,4], sensors [5,6], biomedical applications [7,8]. The most common combination is A site metal ions are Cu 2+ , Zn 2+ , Ni 2+ and B site are Fe 3+ , Al 3+ , respectively [9].…”