Silver Iron Research Articles

Phytogenic aqueous extract mediated fabrication of Ag-Fe2O3 nanohybrids for detoxification of carcinogenic Congo Red dye: An Environmental Remediation approach

<p>In current study environment benign silver-iron oxide (Ag-Fe2O3) nanohybrid structures are fabricated as catalyst for CR dye decolorization. Industrial wastewater stream possesses several toxic dyes which are toxic carcinogen pollutants cause severe environmental disorders. Detoxification of Congo Red dye is carried out by silver-iron oxide nanohybrid structures having latent catalytic efficiency for dye decolorization. Silver iron oxide nanohybrid materials are fabricated from AgNO3, FeSO4/ FeCl3 and Citrus limon aqueous extract by doping AgNPs on Fe2O3 materials. For characterization of Ag-Fe2O3 nanostructures, UV-Visible, X-ray diffraction (XRD), Scanning electron microscope (SEM) and Fourier transform infrared (FT-IR) techniques are used. The crystallite size is measured from Debye Scherer equation and average size calculated is 54.3 nm. Furthermore, UV-Visible spectrophotometer is used to study the catalytic efficiency of Ag-Fe2O3 nanohybrid material which is observed to be >80% within 10 minutes. Moreover, parameters like contact time, dosage of catalyst, temperature and pH are measured to optimize reaction conditions for the dye degradation by adding prepared nanohybrids. The kinetic studies were performed for the degradation reaction and were originate to follow first order kinetics. Reusability test is also applied to check the stability of nanohybrid catalyst that affirmed it to be as highly stable nanomaterial.</p>

RETRACTED ARTICLE: Activity of Silver–Iron Nanoparticles Co-doped Zirconia and Titania Catalysts in the Photodegradation of Drug Molecules and Their Application as Anti-corrosive Agents for Commercial X65 Steel

RETRACTED ARTICLE: Activity of Silver–Iron Nanoparticles Co-doped Zirconia and Titania Catalysts in the Photodegradation of Drug Molecules and Their Application as Anti-corrosive Agents for Commercial X65 Steel

Escherichia coli-assisted synthesis of AgFeO2 nanoparticles for antimicrobial, photocatalytic and hydrogen generation applications

The nanoparticles produced by physical and chemical methods are toxic in one or other way. Green chemistry is an emerging, stable and eco-friendly approach for biological production of nanomaterials. In the present study, Escherichia coli bacterium was utilized for the synthesis of silver iron oxide (AgFeO2) nanoparticles by using precursors of two different salts; iron nitrate (Fe(No3)3 and silver nitrate (AgNO3). Synthesized nanoparticles were characterized by EDX, XRD and SEM. AgFeO2 nanoparticles, members of delafossite family were appraised for bacterial inactivation, photocatalytic degradation of toxic dyes and hydrogen generation through methanolysis. Delafossites are chemically stable compounds with high conductivity and decomposition temperatures (800–925 °C). The antimicrobial activity of AgFeO2 nanoparticles was checked by well diffusion method against ATTC cultures of Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa. Synthesized AgFeO2 nanoparticles were employed for the degradation of Cango red and maximum degradation of 87 % was accomplished with 20 ppm (50 mL) solution of Cango red and 0.10 g AgFeO2 as catalyst and reasonable hydrogen generating potential was also exhibited by the synthesized nanoparticles. As model fungi, Aspergillus niger and Mucor piriformis, are both significantly inhibited by AgFeO2 NPs, while M. piriformis is the target of the compound's greater antifungal action.

Comprehensive response of microbes to Ag and Ag2S nanoparticles and silver spatial distribution in constructed wetlands

This study investigated functional bacteria, key enzymes, and nitrogen metabolism in vertical flow constructed wetlands (CWs) after exposing to silver, silver sulfide nanoparticles (Ag NPs and Ag2S NPs), and silver iron (Ag+), and silver spatial distribution in CWs for 155 days. Ag NPs and Ag2S NPs affected species richness and diversity whereas Ag+ showed the higher the species diversity indices. Sequencing analysis exhibited that Ag NPs or Ag+ significantly inhibited nitrogen metabolic process by hindering the relative activity of functional enzymes, downregulating relative abundances of nrfA, norB and napA for Ag NPs, nxrA gene for Ag+, while Ag2S NPs inhibited relative abundance of nirA. The above results confirmed that NPs or Ag+ significantly reduced nitrogen removal and Ag NPs mainly inhibited NO3−-N removal while Ag+ significantly suppressed NH4+-N removal. This study also found that CWs could effectively remove NPs or Ag+ (about 98 %), and nanoparticles showed higher translocation factors (TFs) values (0.81–1.15 or 0.36), indicating nanoparticles transported easily through substrate layers.

Attractive study of the physical properties of silver iron oxide nanoparticles for biomedical applications

Novel ratios of silver iron nanoparticles with the chemical formulas Ag2Fe2O4 with Ag/Fe ratio = 1/1 and Ag0.5Fe2.5O4 with Ag/Fe ratio = 1/5 were successfully synthesized using a flash auto-combustion technique at 400 °C. Structural properties were studied using XRD (x-ray diffraction), AFM (Atomic Force Microscopy), FESEM (Field Emission Scanning Electron Microscopy), and FTIR (Fourier transform infrared) analyses. The nanosize range determined from XRD analysis lies in 56.6–71.1 nm for Ag0.5Fe2.5O4 and Ag2Fe2O4 nanoparticles. The morphology was analyzed using AFM and FESEM to confirm that the particle size of both samples was spherical and nanosized with agglomeration. Fourier transform infrared (FTIR) analysis was performed to confirm nano-samples’ formation. Both samples were measured using a vibrating sample magnetometer to study their magnetism. By increasing the concentration of iron ions, the saturation magnetization (Ms) increased 5-fold for Ag0.5Fe2.5O4 nanoparticles compared with Ag2Fe2O4 nanoparticles. Moreover, there is a relation between saturation magnetization and antimicrobial activity, in which high (Ms) gives high antibacterial activity. Thus, Ag0.5Fe2.5O4 had a high (Ms) and high efficacy against the tested bacteria. However, Ag2Fe2O4 showed high activity against Candida albicans. Moreover, a high-frequency application was measured from the magnetic measurements, showing that both samples could be applied at a very high frequency (VHF) in the radio wave range. Finally, both samples could be antibacterial materials, particularly Ag0.5Fe2.5O4 nanoparticles. However, Ag2Fe2O4 nanoparticles are strongly recommended for antifungal activity against Candida albicans.

Laser-Accelerated Mass Transport in Oxygen Reduction Via a Graphene-Supported Silver-Iron Oxide Heterojunction.

Mass-transport acceleration is essential toward enhanced electrocatalytic performance yet rarely recognized under irradiation, because light is usually reported to improve charge transfer. We studied laser-enhanced mass transport through the heterojunction between Ag and semiconductor Fe2O3 situated on graphene for oxygen reduction reaction. Because of the decreased mass-transport resistance by 59% under 405 nm laser irradiation, the current density can be enhanced by 180%, which is also supported by a theoretical calculation. This laser-enhanced mass transport was attributed to local photothermal heating and the near-field local enhancement. Easier desorption of OH- species occurring between the Fe and Ag centers under the laser accelerates the mass-transport centers.

Synthesis, characterization, antimicrobial activity, and toxicity evaluation of aminolevulinic acid-silver and silver-iron nanoparticles for potential applications in agriculture.

Aminolevulinic acid (ALA) is considered one of the most critical plants growth regulators and essential precursors for chlorophyll biosynthesis; besides, its photodynamic activity can be used to exterminate larvae and microorganisms in plants and soil. Silver nanoparticles (AgNPs) have unique physicochemical properties and potent antimicrobial, antiviral, and antifungal activities, and in agriculture, their application as nanopesticides has been proposed. In this study, silver and silver-iron nanoparticles capped/stabilized with aminolevulinic acid (ALAAgNPs and ALAAgFeNPs) were synthesized by the photoreduction method and characterized by UV-vis spectroscopy, transmission electron microscopy, and zeta potential analysis. The kinetics of 1O2 generation from ALAAgFeNPs were obtained. The ALANP toxicity was evaluated on stalks of E. densa by observing cell morphology changes and measuring chlorophyll content compared with water-treated plants. Antimicrobial activity was tested against E. coli, P. aeruginosa, and Candida albicans. The results suggested that ALANPs (prepared with [AgNO3] ≤ 0.2 mM and [ALA] ≤ 0.4 mM) could be suitable for applications in the agricultural sector. The presence of ∼0.3 mmol of iron in ALAAgNPs synthesis increased cell uptake and chlorophyll synthesis.

Phase-Controlled Synthesis and Quasi-Static Dielectric Resonances in Silver Iron Sulfide (AgFeS2 ) Nanocrystals.

Ternary metal-chalcogenide semiconductor nanocrystals are an attractive class of materials due to their tunable optoelectronic properties that result from a wide range of compositional flexibility and structural diversity. Here, the phase-controlled synthesis of colloidal silver iron sulfide (AgFeS2 ) nanocrystals is reported and their resonant light-matter interactions are investigated. The product composition can be shifted selectively from tetragonal to orthorhombic by simply adjusting the coordinating ligand concentration, while keeping the other reaction parameters unchanged. The results show that excess ligands impact precursor reactivity, and consequently the nanocrystal growth rate, thus deterministically dictating the resulting crystal structure. Moreover, it is demonstrated that the strong ultraviolet-visible extinction peak exhibited by AgFeS2 nanocrystals is a consequence of a quasi-static dielectric resonance (DR), analogous to the optical response observed in CuFeS2 nanocrystals. Spectroscopic studies and computational calculations confirm that a negative permittivity at ultraviolet/visible frequencies arises due to the electronic structure of these intermediate-band (IB) semiconductor nanocrystals, resulting in a DR consisting of resonant valence-band-to-intermediate-band excitations, as opposed to the well-known localized surface plasmon resonance response typically observed in metallic nanostructures. Overall, these results expand the current library of an underexplored class of IB semiconductors with unique optical properties, and also enrich the understanding of DRs in ternary metal-iron-sulfide nanomaterials.

Biomass solid oxide fuel cell using solid weed waste as fuel

Weed waste is an abundant and carbon-neutral feedstock for energy recovery. A potential approach to improve the efficiency of waste-to-energy conversion is the application of a fuel-cell-type reactor to the treatment system to generate electricity from the feedstock, with high power and energy density. Herein, we report a solid oxide fuel cell (SOFC) that directly uses solid weed waste as fuel. Grasses tested in this study were Miscanthus sinensis, Solidago canadensis, and Pueraria montana. The conversion reactions for these grasses, especially in situ gasification, were effectively catalyzed at 800 °C by a thin layer of a silver–iron(III) oxide mixture that was deposited onto the anode substrate. The use of Solidago canadensis and Pueraria montana provided the highest power density (0.41 W cm−2) and energy density (0.42 Wh g−1), respectively, which were closely related to their lignin and ash contents. Importantly, this SOFC exhibited good performance not only in batch mode but also in continuous free-fall mode.

Accessible Silver-Iron Oxide Nanoparticles as a Nanomaterial for Supported Liquid Membranes.

The present study introduces the process performances of nitrophenols pertraction using new liquid supported membranes under the action of a magnetic field. The membrane system is based on the dispersion of silver–iron oxide nanoparticles in n-alcohols supported on hollow microporous polypropylene fibers. The iron oxide–silver nanoparticles are obtained directly through cyclic voltammetry electrolysis run in the presence of soluble silver complexes ([AgCl2]−; [Ag(S2O3)2]3−; [Ag(NH3)2]+) and using pure iron electrodes. The nanostructured particles are characterized morphologically and structurally by scanning electron microscopy (SEM and HFSEM), EDAX, XRD, and thermal analysis (TG, DSC). The performances of the nitrophenols permeation process are investigated in a variable magnetic field. These studies show that the flux and extraction efficiency have the highest values for the membrane system embedding iron oxide–silver nanoparticles obtained electrochemically in the presence of [Ag(NH3)2]+ electrolyte. It is demonstrated that the total flow of nitrophenols through the new membrane system depends on diffusion, convection, and silver-assisted transport.

Erythrocyte membrane-camouflaged nanoworms with on-demand antibiotic release for eradicating biofilms using near-infrared irradiation

The increase in the number of resistant bacteria caused by the abuse of antibiotics and the emergence of biofilms significantly reduce the effectiveness of antibiotics. Bacterial infections are detrimental to our life and health. To reduce the abuse of antibiotics and treat biofilm-related bacterial infections, a biomimetic nano-antibacterial system, RBCM-NW-G namely, that controls the release of antibiotics through near infrared was prepared. The hollow porous structure and the high surface activity of nanoworms are used to realize antibiotic loading, and then, biomimetics are applied with red blood cell membranes (RBCM). RBCM-NW-G, which retains the performance of RBCM, shows enhanced permeability and retention effects. Fluorescence imaging in mice showed the effective accumulation of RBCM-NW-G at the site of infection. In addition, the biomimetic nanoparticles showed a longer blood circulation time and good biocompatibility. Anti-biofilm test results showed damage to biofilms due to a photothermal effect and a highly efficient antibacterial performance under the synergy of the photothermal effect, silver iron, and antibiotics. Finally, by constructing a mouse infection model, the great potential of RBCM-NW-G in the treatment of in vivo infections was confirmed.

Coating Keplerate based host-guest material PMo12O40 @{Mo72Fe30} surface with silver iron molybdate

The fresh green colored reduced crystals of [HxPMo12O40 ⊂ H4MoVI72FeIII30(CH3COO)15O252(H2O)102] · xH2O (1) dissolved in aqueous AgNO3 solution, when refluxed, results in formation of yellow precipitate which on calcination at 450 °C gives crystalline α-AgFe(MoO4)2. When the dried crystals of host guest [HxPMo12O40 ⊂ H4MoVI72FeIII30(CH3COO)15O254(H2O)98] · ca.60 H2O (2) are treated with aqueous AgNO3 solution in which it is not soluble, a layer of a mixed metal oxide α-AgFe(MoO4)2 is deposited on its surface with simultaneous oxidation of 2 generating a yellow colored compound [{(PMo12O40) ⊂ (Mo72Fe30)} 0.99 ⊂ {AgFe(MoO4)2} 0.01] (3). We have proposed a new synthetic pathway for the construction of a POM based three component hybrid material following a solid–liquid interface reaction, wherein the role of the template and the source of the metal oxide layer are played by the POM Keplerate 2.

Ultrafine Ag–Fe alloys with graphene-based cellular monolith as a novel antimicrobial material

Bimetallic silver–iron nanoparticles (Ag–Fe NPs) are an attractive antimicrobial material because of their multifunctional properties. The antimicrobial performance of Ag–Fe NPs is affected significantly by alloying structure, particle size and composition, but the preparation is a challenge due to the large difference in lattice constants of the two elements. An ultrasonic-assisted in situ reduction method was used here to prepare Ag–Fe/graphene-based cellular monolith (Ag–Fe/GCM) materials with well-defined alloy structure, ultrafine size and abundant hierarchical structure. We found that the antimicrobial activity of such materials decreased but the stability of Ag improved with the increase of Fe content within a certain range. The more active Fe in alloys can protect the Ag from oxidation, which reduces the release of Ag+. However, the release of Fe ions led to more generation of reactive oxygen species compared with Ag/GCM, which maintained a high antibacterial activity. By adjusting Fe content, an Ag–Fe/GCM material with optimal performance was achieved. This work not only provides a method for preparing Ag–Fe alloys but is also useful for understanding its antimicrobial mechanism. Moreover, Ag–Fe/GCM material also performs well in filtering of bacterial pathogens, and is a highly promising material for advanced antimicrobial and water-treatment applications.

Physicochemical and antimicrobial photodynamic chemotherapy (against E. coli) by indium phthalocyanines in the presence of silver–iron bimetallic nanoparticles

In this work, Schiff base indium phthalocyanines: In–Cl tetrakis N,N-dimethyl-4-(methylimino) phthalocyanine (complex 1b) and In–Cl tetrakis phenoxy N,N-dimethyl-4-(methylimino) phthalocyanine (complex 2b) are synthesized from tetra amino and tetra phenoxy amino phthalocyanines, respectively. These complexes were further quartenised with 1,3-propanesultone to form zwitterionic complexes 1 and 2, respectively. Silver–iron dimers (Ag–Fe3O4) and silver-iron core shell (Ag@Fe3O4) nanoparticles (NPs) were linked to the synthesised complexes. The photophysical and photochemical behaviour of the complexes and their conjugates with NPs were investigated in dimethyl sulfoxide. Complexes 2 and 2b and their conjugates were then used for photodynamic antimicrobial chemotherapy on Escherichia coli. The zwitter ionic photosensitiser 2 and its conjugates showed better efficiency for photodynamic antimicrobial chemotherapy compared to their neutral counterparts.

Synthesis of Silver Flakes and Their Application as Conductive Filler for Low-Curing-Temperature Silver Pastes

Silver microparticles have inspired much research interest due to their enhanced properties for use in optical, electric, catalytic, and magnetic applications. One such use is as electrically conductive filler for printed electronics. A manufacturing approach has been developed to prepare low-curing-temperature silver pastes. Firstly, silver flakes were synthesized directly by a one-step aqueous-phase reduction reaction, using silver nitrate as silver salt precursor and iron(II) sulfate heptahydrate as reducing agent. Various silver flake samples were synthesized by controlling experimental parameters such as the reaction temperature, surfactant concentration, and reducing agent concentration. The obtained silver powders were characterized by x-ray diffraction analysis, scanning electron microscopy, and dynamic light scattering measurements. The results revealed that the morphology of the silver powders was a plate-like structure with diameter of 1 μm to 1.5 μm and thickness of 30 nm. The prepared silver flakes were then used directly without ball milling to prepare low-curing-temperature silver pastes. The bulk resistivity of a line screen-printed using silver paste containing 48 wt.% (34 ± 5 vol.%) silver flakes and cured at 140°C for 30 min in air was about (1.773 ± 0.118) × 10−6 Ω m. More importantly, the prepared screen-printed patterns exhibited excellent durability in terms of peel strength and folding endurance.

Core-composite mediated separation of diverse nanoparticles to purity.

A generalized method for sorting nanoparticles based on their cores does not exist; it is an immediate necessity, and an approach incorporating cost-effectiveness and biocompatibility is in demand. Therefore, an efficient method for the separation of various mixed core-compositions or dissimilar metallic nanoparticles to their pure forms at the nano-bio interface was developed. Various simple core-combinations of monodispersed nanoparticles with dual cores, including silver plus gold, iron oxide plus gold and platinum plus gold, to the complex three-set core-combinations of platinum plus gold plus silver and platinum plus iron plus gold were sorted using step-gradient centrifugation in a sucrose suspension. Viscosity mediated differential terminal velocities of the nanoparticles permitted diversified dragging at different gradients allowing separation. Stability, purity and properties of the nanoparticles during separation were evaluated based on visual confirmation and by employing advanced instrumentations. Moreover, theoretical studies validated our experimental observations, revealing the roles of various parameters, such as the viscosity of sucrose, the density of the particles and the velocity and duration of centrifugation, involved during the separation process. This remarkably rapid, cost-efficient and sustainable strategy can be adapted to separate other cores of nanoparticles for various biomedical research purposes, primarily to understand nanoparticle induced toxicity and particle fate and transformations in natural biotic environments.

One-put green synthesis of multifunctional silver iron core-shell nanostructure with antimicrobial and catalytic properties

Bringing two completely different properties into one nanostructure by using individual metals is a difficult goal to achieve. However, recently core-shell metallic nanostructures have introduced as a novel multifunctional nanomaterial with enhanced properties. Iron and silver based nanoparticles are among the most widely applicable nanomaterials in modern industries. Zero-valent iron nanostructures and silver nanoparticles are well known for their applications as catalyst and antimicrobial agent, respectively. In the present study, for the first time, we are reporting a successful fabrication of zero valent iron coated silver nanoparticles (ZVI@AgNPs) by using a green and one-pot synthesis approach. Aqueous leaf extract of Mediterranean cypress (Cupressus sempervirens) was used as a natural source of reducing and capping agent for reduction of both Ag+ and Fe3+ ions. Prepared nanostructures were characterised by a range of analytical techniques namely UV–vis spectroscopy, Transmission Electron Microscopy, X-Ray Diffraction, and Fourier Transform Infra-Red Spectroscopy. The prepared nanostructures were found to be an effective material for dye removal and were capable to remove 98.5% of the initial dye just after 4 h. Based on the results, zero valent iron coating enhanced the antimicrobial potential of AgNPs against Gram-positive bacteria (S. aureus), while showing no significant enhancement against Gram-negative bacteria (E. coli). ZVI@AgNPs, therefore, can be introduced as a novel nanostructure for application in aquatic filter materials to simultaneously reduce microbial and organic contaminants.

Electrocatalytic Oxygen Reduction in Alkaline Medium at\xa0Graphene-Supported Silver-Iron Carbon Nitride Sites\xa0Generated During\xa0Thermal Decomposition of Silver Hexacyanoferrate

Silver-iron carbon nitride, which has been prepared by pyrolysis (under inert atmosphere) of silver hexacyanoferrate(II) deposited on graphene nanoplatelets, is considered here as electrocatalyst for oxygen reduction in alkaline medium (0.1 M potassium hydroxide electrolyte) in comparison to simple silver nanoparticles and iron carbon nitride (prepared separately in a similar manner on graphene nanoplatelets). The performance of catalytic materials has been examined using such electrochemical diagnostic techniques as cyclic voltammetry and rotating ring-disk electrode voltammetry. Upon application of the graphene nanoplatelet-supported mixed silver-iron carbon nitride catalyst, the reduction of oxygen proceeds at more positive potentials, as well as the amounts of hydrogen peroxide (generated during reduction of oxygen at potentials more positive than 0.3 V) are lower relative to those determined at pristine silver nanoparticles and iron carbon nitride (supported on graphene nanoplatelets), when they have been examined separately. The enhancement effect shall be attributed to high activity of silver toward the reduction/decomposition of H2O2 in basic medium. Additionally, it has been observed that the systems based on carbon nitrides show considerable stability due to strong fixation of metal complexes to CN shells.Graphical ᅟ

AgFeOF2: A Fluorine-Rich Perovskite Oxyfluoride.

We synthesized a silver iron oxyfluoride AgFeOF2 by using a high-pressure reaction. Synchrotron X-ray and neutron diffraction, X-ray absorption, and 57Fe Mössbauer spectroscopy indicate that AgFeOF2 crystallizes in the ideal perovskite structure with iron in a trivalent state, although electron microscopy revealed weak super-reflections. A possible partial ordering in the FeO2F4 octahedron is inferred from Mössbauer spectroscopy. The synthesis of the fluorine-rich sample offers an opportunity to study a composition-property relation in AFeIIIO3- nF n ( n = 0, 1, and 2). AgFeOF2 exhibits a G-type antiferromagnetic ordering below TN ≈ 480 K, which is much lower than the n = 0 and 1 cases, suggesting a weaker superexchange interaction between Fe moments via F 2p orbitals (vs O 2p orbitals).

An Overview of the Effects of Heavy Metals Content in Wastewater on Anammox Bacteria

The application of Anammox process in treating nitrogen rich wastewater had been more preferable since the discovery of Anammox process and Anammox bacteria at 1999 due to the advantages of energy saving and cost reduction compared to the conventional nitrofication/denitrificationi process. However, often nitrogen-laden wastewater such as metal refinary wastewater, swine, industrial wastewater, and landfill leachate contain various concentrations of heavy metal ions such as Cadmium, Copper, Lead, Mercury, Nickel, Zinc, Silver and Ferrous iron.