Monovalent Silver Research Articles

Tetrahedrite-(Hg) from the Litija deposit, Central Slovenia: Mineral chemistry insights into fluid evolution processes

For over a century, the main carrier of Silver in the Litija mineralisation has been debated, with fine-grained galena often identified as the primary host. The in-situ quantitative microanalysis of a silver-bearing ore from the Alma orebody reveals that silver is not hosted within the galena but occurs instead as inclusions within tetrahedrite-(Hg). The mechanism of silver incorporation in tetrahedrite is complex and may occur through atom-to-atom substitution, where monovalent silver replaces monovalent copper (Ag+ ↔ Cu+). Additionally, silver can be present as a separate phase, either as nanoscale inclusions of acanthite or through the replacement of pre-existing silver-rich chalcopyrite. Elemental correlations and minor variations in the element distribution within the studied tetrahedrite provide insights into the chemistry of the mineralizing fluid. These findings suggest an initial reducing, near-neutral, low-chlorinity fluid promoting incorporation of Sb3+ and Hg2+ into tetrahedrite. This fluid subsequently mixed with high-salinity, Cl-rich, near-neutral fluid transporting Zn2+. Sulfide precipitation introduced additional acidity in the mixed fluids, altering the pH and promoting As3+ and Zn2+ incorporation into tetrahedrite. We suggest that Hg2+ ↔ Zn2+ substitution in tetrahedrite is influenced by pH fluctuations and fluid mixing. These findings provide new insights into the geochemical processes governing trace element incorporation in sulfosalt minerals and offer valuable framework for understanding mineralization in similar hydrothermal systems worldwide.

Structure and size of complete hydration shells of metal ions and inorganic anions in aqueous solution.

The structures of nine hydrated metal ions in aqueous solution have been redetermined by large angle X-ray scattering to obtain experimental data of better quality than those reported 40-50 years ago. Accurate M-OI and M-(OI-H)⋯OII distances and M-OI(H)⋯OII bond angles are reported for the hydrated magnesium(II), aluminium(III), manganese(II), iron(II), iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) ions; the subscripts I and II denote oxygen atoms in the first and second hydration sphere, respectively. Reported structures of hydrated metal ions in aqueous solution are summarized and evaluated with emphasis on a possible relationship between M-OI-OII bond angles and bonding character. Metal ions with high charge density have M-OI-OII bond angles close to 120°, indicative of a mainly electrostatic interaction with the oxygen atom in the water molecule in the first hydration shell. Metal ions forming bonds with a significant covalent contribution, as e.g. mercury(II) and tin(II), have M-OI-OII bond angles close to 109.5°. This implies that they bind to one of the free electron pairs in the water molecule. Comparison of M-O bond distances of hydrated metal ions in the solid state with one hydration shell, and in aqueous solution with in most cases at least two hydration shells, shows no significant differences. On the other hand, the X-O bond distance in hydrated oxoanions increases by ca. 0.02 Å in aqueous solution in comparison with the corresponding X-O distance in the solid state. A linear correlation is observed between volume, calculated from the van der Waals radius of the hydrated ion, and the ionic diffusion coefficient in aqueous solution. This correlation strongly indicates that monovalent metal ions, except lithium and silver(I), and singly-charged monovalent oxoanions have a single hydration shell. Divalent metal ions, bismuth(III) and the lanthanoid(III) and actinoid(III) ions have two hydration shells. Trivalent transition and tetravalent metal ions have two full hydration shells and portion of a third one. Doubly charged oxoanions have one well-defined hydration shell and an ill-defined second one.

Methylene bis(p-chlorobezodithioate): Synthesis, characterization and its use as analytical reagent for Silver ion

The study included the preparation and diagnosis of disulfur ligands (Dithiols) and the preparation of their complex with monovalent (Silver), which included the the following steps: First: preparation of the sulfur compound through the reaction of Grignard reagent (ClPhMgX), with carbon disulfide (CS2), this step form [ClPhCS2]- , an acidic liquid sulfur compound which was converted into a dimer compound by second step :- reacting with (Benzene tetra methyl ammonium hydroxyl) which produce a negatively charged compound [ClPhCS2]-, which is a viscous, hydrated compound with a strong sulfur smell. The product [ClPhCS2]- react with dichloromethane (DCM) which produce (methylene-bis (p-Chlorodithiobenzoate). Which is characterized with (IR,UV-VIS, 1H-NMR, 13C spectroscopy , mass spectrometry) then followed by Analytical study for the prepared compound were investigated by preparation of their complex with Monovalent (Silver), where the stability constants of the prepared complex were studied, which showed the stability of the complex at room temperature and at pH (PH = 8). The absorbance of the complex for UV-Vis. light was studied and the mole ratio (M: L) was studied. From the study of spectroscopic methods.

Silver Nanoparticles' Therapeutic Antibacterial, Antiproliferative, and Toxicological Effects.

Silver nanoparticles, among others, have broad-spectrum antimicrobial properties. Silver nanoparticles have suppressed dangerous microorganisms in medical and agricultural settings in several studies. Chemicals are harmful to humans and the environment, raising awareness of bioactive synthetic methods. These methods produce nanoparticles with better physicochemical qualities, stability, and toxicity. Biogenic nanoparticles can be made from bacterial and fungal byproducts that reduce and stabilize. Encapsulating these nanoparticles with biomolecules from the producing organisms may boost stability and biological activity. Nanoparticles' quick, clean, cheap, and ecological biologic manufacturing technique increases biocompatibility. Silver nanoparticles affect fish, algae, cell-based in vitro procedures, and microbes. Even though most of these studies were done quickly in well-regulated labs with much higher silver ion concentrations than in real life. Many silver types undergo long-term chemical transformation at extremely low levels (ng/L to g/L) in aquatic ecosystems. Thus, silver nanoparticles' environmental and health hazards need additional investigation. Recently detected antimicrobial silver at 10102 μg/mL. Multiple processes make silver nanoparticles dangerous. Basic (Ag0) and monovalent (Ag+) silver are most poisonous. Silver framework free ions affect silver toxicity. ROS damage DNA when elemental or zero-valent silver penetrates tissues. Packaged foods, contaminated water, swimming pools, antifouling, nasal and throat medicines, and other pharmaceuticals include silver nanoparticles. Consumption accumulates silver ions in subcutaneous fat. Prolonged exposure causes argyria-blue-gray skin. Silver inhibits Na+ and Cl absorption, disrupting electrolytes. Airborne silver nanoparticles may influence chronic pulmonary disease patients. Silver ions oxidize enzyme thiols, hindering electron transport and DNA replication. Ag+ rapidly damages DNA and RNA. Silver nanoparticle breakdown into silver ions creates germ-killing ROS. Silver nanoparticles are more hazardous than silver ions in the same atmosphere.

Visible light-driven photocatalytic reduction of monovalent silver using a composite of Ni3Bi2S2 and O-doped gC3N4

In this study, nickel bismuth sulphide (Ni2Bi2S3) was synthesized through solvothermal method and was used to functionalize oxygen-doped graphitic carbon nitride to form a nanocomposite (Ni2Bi2S3/O-gC3N4). Characterizations of the nanocomposite were carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and UV–vis spectrophotometer. The nanocomposite was used to photocatalytically reduce monovalent silver to useful metallic silver. The effects of process parameters including Ag+ concentration, pH of the solution, the dosage of the photocatalyst, light intensities, addition of persulfate and mixed organic pollutants were studied, and the data obtained were fitted into pseudo-first order kinetics. About 93.08% (pseudo first order rate constant of 0.0460 min−1) of Ag+ was photocatalytically removed within 1 h using 25 mg of the photocatalyst. Mixed organic pollutants and persulfate were found to have inhibitory effects on the rate of photocatalytic reduction. Finally, the Ni2Bi2S3/O-gC3N4 photocatalyst was found to retain over 80% of its efficiency even after three cycles, and the scavenging experiment revealed that electrons, holes and superoxide played prominent roles in the photocatalytic process.

Experimental and theoretical validation of nano filters fabricated through green synthesized silver nanoparticles

The present study focuses on fabrication of nanofibrous membrane to filter microbial aerosols using silver nanoparticles. Nanofibrous membrane was formed with silver nanoparticles (AgNp) and polyvinyl butyral (PVB) using electro spinning technology. The optimized nanofibers were characterized for the effective formation, morphology, and thermal sensitivity using High Resolution Scanning Electron microscopy (HR-SEM), Energy dispersive X-ray spectroscopy (EDS), and Thermo gravimetric study (TGA). Chemical components present in the aqueous leaf extract that reduces the monovalent silver were identified using Fourier Transform Infrared (FT-IR) spectroscopy. HR-SEM analysis confirmed homogenous fiber diameter with smooth surface for the obtained AgNPs-PVB membranes. The PVB loaded AgNPs have shown up to 19% weight loss at 956°C which was ascertained through TGA. Microbial loading on the filter, microbial survival, filtration efficiency, and antimicrobial efficiency of the fabricated membrane were evaluated. The fabricated membrane exhibited both bacterial and fungal filtration efficiency to an extent of 98.81% and 98.85%, respectively. Experimental data were compared theoretically using predicted mathematical model that established best fitting and was highly compatible.

Silver ions and silver nanoparticles removal by coffee derived biochar using a continuous fixed-bed adsorption column

Even low concentration monovalent silver (Ag+) and silver nanoparticles (Ag NPs) are emerging environmental threats, seeking an eco-friendly and cost-effective continuous treatment process to mitigate their pollution. In this study, an attempt has been made to investigate the potential of spent coffee grounds (SCGs) biochar in a fixed-bed column, to remove silver ions and silver nanoparticles from wastewater. A series (adsorption and desorption) of fixed-bed column experiments were performed under different operating conditions to determine the breakthrough curves (BTCs) and understand the effect of initial concentration (50–100 mg/L), the quantity of biochar (0.5–1 g), and the form of silver Ag+ and Ag NPs on biochar removal capacity. Thomas and Yoon-Nelson models were applied to simulate different column parameters, such as breakthrough time, saturation time, the volume of treated effluent, and percentage of removal. These simulated results could assist in the scale-up of the process for an actual industrial operation. Experimental data showed good agreement with both Thomas and Yoon-Nelson models, where the simulated values were closely matched with the experimental values. Biochar was collected after the adsorption and characterised to confirm the morphology, crystal structure, and ionic state of silver. The saturated column was regenerated by 0.05 M HNO3 as eluent and used at least 3 times with 15% capacity loss compared to initial performance, which demonstrated the viability and effectiveness of the biochar adsorption process.

New 3D Coordination Polymer Based on the Tetrapyridyl Derivative of Thiacalix[4]arene in the 1,3-Alternate Configuration and Hexanuclear Clusters of Monovalent Silver: Synthesis and Structure

New 3D Coordination Polymer Based on the Tetrapyridyl Derivative of Thiacalix[4]arene in the 1,3-Alternate Configuration and Hexanuclear Clusters of Monovalent Silver: Synthesis and Structure

Crystal structure, XANES and charge distribution investigation of krennerite and sylvanite: analysis of Au-Te and Te-Te bonds in Au1-xAgxTe2 group minerals.

The structure refinement and XANES study of two gold-silver-tellurides [Au1+xAgxTe2, krennerite (x = 0.11-0.13) and sylvanite (x = 0.29-0.31)] are presented and the structures are compared with the prototype structure of calaverite (x = 0.08-0.10). Whereas the latter is well known for being incommensurately modulated at ambient conditions, neither krennerite nor sylvanite present any modulation. This is attributed to the presence of relatively strong Te-Te bonds (bond distances < 2.9 Å) in the two minerals, which are absent in calaverite (bond distances > 3.2 Å). In both tellurides, trivalent gold occurs in slightly distorted square planar coordination, whereas monovalent gold, partly substituted by monovalent silver, presents a 2+2+2 coordination, corresponding to distorted rhombic bipyramids. The differentiation between bonding and non-bonding contacts is obtained by computation of the Effective Coordination Number (ECoN). The CHARge DIstribution (CHARDI) analysis is satisfactory for both tellurides but suggests that the Te-Te bond in the [Te3]2- anion is not entirely homopolar. Both tellurides can therefore be described as Madelung-type compounds, despite the presence of Te-Te in both structures.

Cellulose nanofibers aerogels functionalized with AgO: Preparation, characterization and antibacterial activity

In the experiment, a chemical oxidation method was used to prepare nano-divalent silver oxide powder with a particle size of about 10 nm. Compared with silver nanoparticles and monovalent silver compounds, nano‑silver oxide has better antibacterial properties. The cellulose antibacterial aerogel was prepared by combining it with cellulose nanofibrils and using freeze-thaw cycles and freeze-drying methods. The microscopic morphology, mechanical properties, in vitro release of silver ions, antibacterial properties and biodegradability of composite aerogels were studied. The porosity of the cellulose antibacterial aerogel can reach 94%, the swelling rate was greater than 1000%, and the pore size was between 13 and 15 nm, which showed a larger storage space and attachment site for the aerogel. The diameter of the inhibition zone of the aerogel against Escherichia coli and Staphylococcus aureus was 23 mm and 20 mm respectively, and the aerogels still exhibited significant antibacterial activities with more than 99.5% reductions in Escherichia coli and Staphylococcus aureus, which shows highly effective antibacterial properties. This research proposes an economical and novel preparation method of antibacterial cellulose aerogel, making it a candidate material with high efficiency, broad-spectrum antibacterial and more suitable for life needs.

Multifaceted phytogenic silver nanoparticles by an insectivorous plant Drosera spatulata Labill var. bakoensis and its potential therapeutic applications

The current investigation highlights the green synthesis of silver nanoparticles (AgNPs) by the insectivorous plant Drosera spatulata Labill var. bakoensis, which is the first of its kind. The biosynthesized nanoparticles revealed a UV visible surface plasmon resonance (SPR) band at 427 nm. The natural phytoconstituents which reduce the monovalent silver were identified by FTIR. The particle size of the Ds-AgNPs was detected by the Nanoparticle size analyzer confirms that the average size of nanoparticles was around 23 ± 2 nm. Ds-AgNPs exhibit high stability because of its high negative zeta potential (− 34.1 mV). AFM studies also revealed that the Ds-AgNPs were spherical in shape and average size ranges from 10 to 20 ± 5 nm. TEM analysis also revealed that the average size of Ds-AgNPs was also around 21 ± 4 nm and the shape is roughly spherical and well dispersed. The crystal nature of Ds-AgNPs was detected as a face-centered cube by the XRD analysis. Furthermore, studies on antibacterial and antifungal activities manifested outstanding antimicrobial activities of Ds-AgNPs compared with standard antibiotic Amoxyclav. In addition, demonstration of superior free radical scavenging efficacy coupled with potential in vitro cytotoxic significance on Human colon cancer cell lines (HT-29) suggests that the Ds-AgNPs attain excellent multifunctional therapeutic applications.

Silver-exchanged CHA zeolite as a CO2-resistant adsorbent for N2/O2 separation

Zeolite Li-X is considered the best adsorbent for air separation (i.e., N 2 /O 2 one). However, this zeolite adsorbent suffers from serious limitations of preparation and process operation. Here, we report that Ag + -exchanged chabazite (Ag-CHA-6.0) with a Si/Al ratio of 6.0 shows comparable N 2 /O 2 separation performance, but higher CO 2 resistance than Li-X under N 2 /O 2 simulated conditions. The characterization results reveal that its excellent separation performance may be due to the preferential formation of partially charged silver clusters (Ag n δ+ ) within the CHA framework upon activation under a dynamic vacuum of 10 −3 Torr at 523 K. The intrazeolitic formation of these Ag n δ+ clusters, whose ability to form π-complexation with N 2 is higher than monovalent silver ions, was found to depend not only on the structure type of the zeolite support, but also its framework Si/Al ratio. • Ag + -exchanged zeolites with different framework topologies and Si/Al ratios are studied in N 2 /O 2 separation. • Ag-CHA-6.0 shows comparable N 2 /O 2 separation performance with commercial Li-X. • Ag-CHA-6.0 exhibits higher resistance to CO 2 than Li-X. • Partially charged silver clusters in Ag-CHA-6.0 contribute to its excellent N 2 /O 2 separation.

Formation of an Ag→Al dative bond is avoided in reactions of an alane/tris(phosphine) ligand with monovalent silver.

An alane/tris(phospine) ligand reacts with AgOTf by coordination of three phosphines to the Ag center and transfer of triflate to the tris(pyrrolyl) Al site. Reaction with Ag[HCB11Cl11] results in the coordination of two phosphines to Ag and one to Al, with no significant Ag-Al bonding in either structure.

STRUCTURE OF “COORDINATION OLIGOMERS” BASED ON COMPLEXES OF THIOPHOSPHORYLTHIOUREA COMPOUNDS WITH MONOVALENT COPPER AND SILVER CATIONS

Molecular and crystal structures of two polynuclear complexes of monovalent silver and copper with chelate thiophosphorylthiocarbamide ligands is determined within the study of complexing properties of N-thiophosphorylated thioureas with respect to copper(I) and silver(I) cations. In crystals, these complexes are shown to form “coordination oligomers” (closed polynuclear complexes) through coordination bonds of bridging sulfur atoms of thiocarbamide groups.

Structure of Complexes of Thiophosphorylthiourea Compounds with a Silver(I) Cation and Triphenylphosphine

Molecular and crystal structures of three monovalent silver complexes with chelate thiophosphorylthiourea ligands and triphenylphosphine are determined in the context of studying complexing properties of N-thiophosphorylated thioureas, thioamides, and thiosemicarbazides with the general formula RC(S)NHP(S)(Oi-Pr)2 (R = AlkNH, Alk2N, ArNH, PyNH, Ph, PhNHNH, NH2(Et)N) towards copper (I) and silver (I) cations.

Silver ZK-5 zeolites for selective ethylene/ethane separation

The development of efficient adsorbents for olefin/paraffin separation has attracted great attention, because an alternative energy-efficient technology is required to move away from the energy intensive cryogenic distillation processes. Here, we have prepared two silver-exchanged ZK-5 (Ag-ZK-5) zeolites with low (2.9) and high (3.7) Si/Al ratios, as well as various other cation-exchanged forms, for ethylene/ethane separation and compared their separation properties with those of zeolites Na-, Ca- and Ag-A with Si/Al = 1.0 and Ag-UZM-9 with Si/Al = 3.7. Among the zeolite adsorbents tested here, Ag-ZK-5 with Si/Al = 3.7 has the highest ethylene/ethane selectivity (2.54) at 298 K in vacuum-swing adsorption mode, together with fast adsorption kinetics. While the breakthrough results hint at its applicability in concentrated ethylene/ethane streams, the outstanding performance of this Ag-ZK-5 for ethylene/ethane separation appears to be due to a combination of its unique framework topology and composition (Al content) which can stabilize monovalent silver ions.

Структура «координационных олигомеров» на основе комплексов тиофосфорилтиокарбамидных соединений с катионами одновалентной меди и серебра

В плане изучения комплексообразующих свойств N-тиофосфорилированных тиомочевин по отношению к катионам меди(I) и серебра(I) установлена молекулярная и кристаллическая структура двух полиядерных комплексов одновалентного серебра и меди с хелатными тиофосфорилтиокарбамидными лигандами. Показано, что в кристаллах эти комплексы образуют за счет координационных связей мостиковых атомов серы тиокарбамидных групп «координационные олигомеры» — замкнутые полиядерные комплексы.

The mechanistic actions of different silver species at the surfaces of polyacrylonitrile nanofibers regarding antibacterial activities

The mechanism of action and toxicity of silver species have been suggested by numerous direct observations. However, as far as we are concerned, comprehensive research to compare modes of action between different silver species at identical silver contents has not yet been reported. The activities of silver species at the interfaces of nanofiber scaffolds and bacterial medium under the impediment of chloride salt, present in antibacterial assays, are very complicated and could bring deeper understanding for research upon antibacterial applications using silver. Here, we prepared silver nitrate, silver zero-valent nanoparticles, and silver mono-valent nanoparticles, incorporated in the nanofiber scaffolds at similar silver contents, then, compared all samples regarding antibacterial effects and fibroblast cytotoxicity. For confirming the success of fabrication, SEM, TEM, EDS, and FT-IR were implemented. Silver nanoparticles were observed to adhere on the nanofibers for Ag2O-PAN 1/20, Ag2O-PAN 1/5, Ag-PAN 1/20, and Ag-PAN 1/5 samples. The XRD spectra exhibited different sets of peaks for zerovalent and monovalent silver nanoparticles, which gave evidence about the nature of silver species incorporated in nanofibers. The XPS data gave an insight into the interactions between silver and the other molecules in the polymer matrix. The antibacterial evaluation gave the demonstration for theories about silver actions in the bacterial medium with the presence of halide anions, which sabotaged the antibacterial actions of silver nitrate and made it the least potent antibacterial agent among different silver species.

Addition of Monovalent Silver Cations to CH3NH3PbBr3 Produces Crystallographically Oriented Perovskite Thin Films

The incorporation of monovalent silver (Ag+) cations into methylammonium lead bromide (CH3NH3PbBr3) perovskite films leads to a strongly preferred (001) crystallographic orientation on a wide variety of substrates, ranging from glass to mesoporous TiO2. CH3NH3PbBr3 films deposited without Ag+ exhibit only a weakly preferred (011) orientation. Compositional maps and depth profiles from time-of-flight secondary ion mass spectrometry (TOF-SIMS) reveal Ag+ segregated to grain boundaries and interfaces. In photovoltaic devices (PVs), addition of Ag+ to MAPBr films resulted in poorer device performance, most likely because of the observed Ag+ segregation in the films.

Structural and dielectric features of silver doped sodium antimonate glass ceramics

The objective of this work is to explore the Ag ion concentration dependence on structural and dielectric characteristics of Na2OSb2O3: Ag2O glass ceramics. The prepared glass ceramics were characterized by XRD, XPS, SEM, TEM, EDS and DSC techniques. These studies have revealed that the samples are composed of multiple crystal grains entrenched in the remnant amorphous phase. The IR and Raman spectroscopic studies indicated increasing degree of polymerization of the glass network with increase of Ag2O concentration up to 0.1 mol%. This is attributed to increasing concentration of tetrahedral Sb5+ ions that take part in the glass network forming. Optical absorption spectra have exhibited surface plasmon resonance (SPR) band in the wavelength region 400–450 nm. Quantitative studies on dielectric properties were performed over wide ranges of frequency and temperature and the variations of these properties with the concentration of Ag2O are discussed in the light of various polarization processes. Dipolar orientational effects exhibited by electric moduli spectra suggested multiple relaxation times for electric dipoles. The observed decrease of A.C. conductivity (that contains both ionic and polaronic components) with increase of Ag2O content up to 0.1 mol% is attributed to the increasing degree of polymerization of the glass network that hinders the migration of charge carriers. The polaronic conduction is understood due to exchange of polarons between Sb3+ ‒ Sb5+ and Ag0 Ag+ ions, while ionic conductivity is predicted due to transport of monovalent silver and Na+ ions. A changeover of polaronic to ionic conductivity seemed to take place at about 0.1 mol% Ag2O.