Precipitation Of AgCl Research Articles

Visible light response AgBr/Ag3PO4 hybrid for removal of anionic dye and tetracycline hydrochloride in water

The AgBr/Ag3PO4 obtained under the condition of pH 7.0, 453 K and reaction of 12 h was a visible-light response catalyst and the absorption spectrum ranges from 200 to 560 nm.The as-fabricated samples were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Scanning electron microscopy, UV–Vis diffuse reflectance spectroscopy. Compared with bare Ag3PO4 or AgBr, it displayed much higher photocatalytic property for tetracycline hydrochloride (TC) degradation under visible light. The main element nitrogen ions were changed into NO3 − and NH4 +, and chloridion ion presumably formed AgCl precipitation or some oxidation state of chloridion during the photodegradation process, the rate of TC photodegradation and mineralization can reach 96.1 and 60.1%, respectively.

A rapid determination of chloride in saturated paste extracts of salt-affected soils using EC change upon AgCl precipitation

A rapid determination of chloride in saturated paste extracts of salt-affected soils using EC change upon AgCl precipitation

Synthesis of silver nanoparticles in the presence of diethylaminoethyl-dextran hydrochloride polymer and their SERS activity

The silver nanoparticles (AgNPs) were synthesized upon γ-irradiation of AgNO3 precursor suspensions in the presence of diethylaminoethyl-dextran hydrochloride (DEAE-dextran) cationic polymer as a stabilizer. The dose rate of γ-irradiation was ~32 kGy h−1, and absorbed doses were 30 and 60 kGy. The γ-irradiation of the precursor suspension at acidic or neutral pH conditions produced predominantly the silver(I) chloride (AgCl) particles, because of the poor solubility of AgCl already present in the precursor suspension. The origin of AgCl in the precursor suspension was due to the presence of chloride ions in DEAE-dextran hydrochloride polymer. The addition of ammonia to the precursor suspension dissolved the AgCl precipitate, and the γ-irradiation of such colourless suspension at alkali pH produced a stable aqueous suspension with rather uniform spherical AgNPs of approximately 30 nm in size. The size of AgNPs was controlled by varying the AgNO3/DEAE-dextran concentration in the suspensions. The surface-enhanced Raman scattering (SERS) activities of synthesized AgNPs were examined using organic molecules rhodamine 6G, pyridine and 4-mercaptobenzoic acid (4-MBA). The NaBH4 was used as SERS aggregation agent. The SERS results have shown that in the presence of synthesized AgNPs, it was possible to detect low concentration of tested compounds.

Halide removal from waters by silver nanoparticles and hydrogen peroxide

The objective of this study was to remove halides from waters by silver nanoparticles (AgNPs) and hydrogen peroxide (H2O2). The experimental parameters were optimized and the mechanism involved was also determined. The AgNP/H2O2 process proved efficacious for bromide and chloride removal from water through the selective precipitation of AgCl and AgBr on the AgNP surface. The optimal AgNP and H2O2 concentrations to be added to the solution were determined for the halide concentrations under study. The removal of Cl− and Br− anions was more effective at basic pH, reaching values of up to 100% for both ions. The formation of OH, O2−, radicals was detected during the oxidation of Ag(0) into Ag(I), determining the reaction mechanism as a function of solution pH. Moreover, the results obtained show that: i) the efficacy of the oxidation of Ag(0) into Ag(I) is higher at pH11, ii) AgNPs can be generated by the O2− radical formation, and iii) the presence of NaCl and dissolved organic matter (tannic acid [TAN]) on the solution matrix reduces the efficacy of bromide removal from the medium due to: i) precipitation of AgCl on the AgNP surface, and ii) the radical scavenger capacity of TAN. AgNPs exhausted can be regenerated by using UV or solar light, and toxicity test results show that AgNPs inhibit luminescence of Vibrio fischeri bacteria.

Macrocycle-assisted synthesis of non-stoichiometric silver(i) halide electrocatalysts for efficient chlorine evolution reaction.

The electrocatalytic oxidation of chloride to chlorine is a fundamental and important electrochemical reaction in industry. Herein we report the synthesis of non-stoichiometric silver halide nanoparticles through a novel macrocycle-assisted bulk-to-cluster-to-nano transformation. The acquired positively charged nanoparticles expedite chloride transportation by electrostatic attraction and facilitate the formation of silver polychloride catalytic species on the surface, thus functioning as efficient and selective electrocatalysts for the chlorine evolution reaction (CER) at a very low overpotential and within a wide concentration range of chloride. The formation of uncommon non-stoichiometric nanoparticles prevents the formation of a AgCl precipitate and exposes more coordination unsaturated silver atoms to catalyze CER, finally causing a large enhancement of the atomic catalytic efficiency of silver. This study showcases a promising approach to achieve efficient catalysts from a bottom-up design.

Environmentally friendly recovery of Ag from end-of-life c-Si solar cell using organic acid and its electrochemical purification

Environmentally friendly and reusable methanesulfonic acid (MSA) was used with the addition of an oxidizing agent to extract Ag from solar cells. Recovery using varying MSA:H2O2 mixing ratios of 100:0, 90:10, 75:25, 50:50, and 0:100 revealed that Ag can be effectively extracted in a MSA-rich solution. The concentration of Ag ions dissolved in each mixture was analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), which established that the optimal extraction condition is a MSA:H2O2 ratio of 90:10. The addition of HCl to the leaching solution used for Ag recovery prompted the precipitation of AgCl, which was then reacted in turn with NaOH and H2O2 to recover Ag metal powder. This Ag metal powder was analyzed by glow discharge mass spectrometry (GDMS) and found to have a low purity of around 99% (2N), but this was found to be improved through subsequent electrorefining to a purity of 99.995% (4N5).

Silver ions eluted from partially protected silver nanoparticles.

The most prominent character of a new type of antibacterial urological catheters is the zebra-stripe pattern of a silver film, which is plated electroless on their interior wall and capped by a very thin semipermeable layer of parylene. This design effectively controls the release rate of Ag(+) ions in artificial urine, which has been measured as function of time with optical emission spectroscopy. By evaluating the minimum inhibitory concentration against certain strains of bacteria with solutions of AgNO3 of known concentration with the method of optical density and applying this analysis to the silver-eluting catheters, it was shown that this moderation prolongs the period of their application significantly. But to act as antibacterial agent in chlorine-containing solutions, as in urine, the presence of urea is required to avoid precipitation of AgCl and to meet or even exceed the minimum inhibitory concentration of Ag(+). The quality of the silver depot layer was further determined by the deposition rate and its morphology, which revealed that the film consisted of grains with a mean size of 150 nm.

Kinetics and Morphological Analysis of Silver Platinum Bimetallic Nanoparticles

Kinetics of a one-pot core–shell synthesis of bimetallic (BM) silver–platinum (Ag–Pt) nanoparticles (NPs) by simultaneous reduction of 1:1 mol fraction of precursors H2PtCl6·6H2O and AgNO3 in aqueous solution is reported. Kinetics analysis was done by plotting UV–visible absorptions versus reaction time with a first-order fitting. Recorded constants of Ag NPs (0.079 s−1), Ag–Pt NPs 1:1 (0.082 s−1), and Pt NPs (0.006 s−1) were obtained. The NPs suspension solutions were clear, free from AgCl precipitate, and had characteristic optical properties of 450 nm (Ag NPs), while there were no observable bands for Pt and BM NPs. Morphological analysis using transmission electron microscopy, energy-dispersive X-ray spectroscopy (EDX), and selected area electron diffraction (SAED) depicted spherical aggregates of Ag NPs, Pt NPs and core shell Pt–Ag NPs 1:1 of average size of 60, 2.5, and 20 mm, respectively. Presence of the Ag and Pt elemental composition in the nanoparticle suspensions was confirmed by EDX. SAED ring patterns revealed a single face-centered cubic crystalline nature of Ag NPs and showed typical Pt-based BMs randomly overlapped ring pattern with sharp diffraction spots.

Silver release from nanocomposite Ag/alginate hydrogels in the presence of chloride ions: experimental results and mathematical modeling

A stepwise experimental and mathematical modeling approach was used to assess silver release from nanocomposite Ag/alginate microbeads in wet and dried forms into water and into normal saline solution chosen as a simplified model for certain biological fluids (e.g., blood plasma, wound exudates, sweat, etc). Three phenomena were connected and mathematically described: diffusion of silver nanoparticles (AgNPs) within the alginate hydrogel, AgNP oxidation/dissolution and reaction with chloride ions, and diffusion of the resultant silver-chloride species. Mathematical modeling results agreed well with the experimental data with the AgNP diffusion coefficient estimated as 1.3 × 10−18 m2 s−1, while the first-order kinetic rate constant of AgNP oxidation/dissolution and diffusivity of silver-chloride species were shown to be inversely related. In specific, rapid rehydration and swelling of dry Ag/alginate microbeads induced fast AgNP oxidation/dissolution reaction with Cl− and AgCl precipitation within the microbeads with the lowest diffusivity of silver-chloride species compared to wet microbeads in normal saline. The proposed mathematical model provided an insight into the phenomena related to silver release from nanocomposite Ca-alginate hydrogels relevant for use of antimicrobial devices and established, at the same time, a basis for further in-depth studies of AgNP interactions in hydrogels in the presence of chloride ions.

Antibacterial Activity of Cetyltrimethylammonium Bromide Modified Silver-Bentonite

Organo-Ag-bentonite was prepared by the attachment of cationic surfactant cetyltrimethylammonium bromide on silver(A)g-exchanged bentonite. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and energy dispersive X-ray (EDX) analysis and antibacterial assay was performed against Escherichia coli in different percentage of saline solutions through minimum inhibition concentration (MIC) method. Organo-Ag-bentonite showed higher antibacterial activity than organo-bentonite and Ag-bentonite especially in saline solution suggesting that the precipitation of AgCl in the presence of Ag-bentonite in saline solution could be avoided by the attachment of cationic surfactant on Ag-bentonite surfaces, hence increased their antibacterial activity.

Impact of Different Washing Conditions on the Release of Ag Species from Textiles

The paper investigates the Ag release from textiles (socks available in shops, cotton and viscose filled with Ag nanoparticles–AgNPs) into a washing solution under different conditions. The released Ag amount depended on various factors, such as test media (chemical composition, temperature and water volume), metal contents, and textile impregnation conditions. Furthermore, it turned out that the textile type and colour were the main parameters affecting the Ag release. The Ag concentration in the washing solution ranged between 0.015 μg/l and 4.44 μg/l (socks) and between 0.61 μg/l and 103 μg/l (AgNPs–filled cotton). The total Ag percentage released into water during one washing varied considerably among textiles (from less than 1 to 34%). In the tap water presence, the released Ag load decreased from 6.82 to 1.35 μg/l due to the AgCl and/or Ag2CO3 precipitation. The bleaching process had a strong effect on the quality and speciation of Ag rleased during the washing process. For example, the Ag concentration in the washing solution changed from 0.8 μg/l to 12.9 μg/l and was higher by 20 times (white socks) to 170 times (black socks) when compared with washing in water without any oxidising agent. The washing of nano–Ag–treated textiles may have potentially released both ionic and particle forms as smaller AgNPs dissolved more rapidly than large AgNPs. The results of the present study demonstrate that the water solution containing Ag revealed a toxic effect on D. magna and V. fischeri. Among the tested species, D. magna was the most sensitive and revealed acute toxicity for low EC50 values. The V. fischeri response was less sensitive due to the physiological state of the bacteria.

Methylviologen mediated electrochemical reduction of AgCl—A new route to produce a silica core/Ag shell nanocomposite material in solution

Abstract Methylviologen mediated electrochemical reduction of AgCl precipitate to Ag 0 in the presence of alkylamino-modified silica nanoparticles (SiO 2 -NHR) in an aqueous medium was performed. The main products of reduction at potentials of the MV 2 + /MV •+ redox couple are spherical SiO 2 -NHR/Ag core/shell nanoparticles (size range 120–160 nm) in solution.

A half-reaction alternative to water oxidation: chloride oxidation to chlorine catalyzed by silver ion.

Chloride oxidation to chlorine is a potential alternative to water oxidation to oxygen as a solar fuels half-reaction. Ag(I) is potentially an oxidative catalyst but is inhibited by the high potentials for accessing the Ag(II/I) and Ag(III/II) couples. We report here that the complex ions AgCl2(-) and AgCl3(2-) form in concentrated Cl(-) solutions, avoiding AgCl precipitation and providing access to the higher oxidation states by delocalizing the oxidative charge over the Cl(-) ligands. Catalysis is homogeneous and occurs at high rates and low overpotentials (10 mV at the onset) with μM Ag(I). Catalysis is enhanced in D2O as solvent, with a significant H2O/D2O inverse kinetic isotope effect of 0.25. The results of computational studies suggest that Cl(-) oxidation occurs by 1e(-) oxidation of AgCl3(2-) to AgCl3(-) at a decreased potential, followed by Cl(-) coordination, presumably to form AgCl4(2-) as an intermediate. Adding a second Cl(-) results in "redox potential leveling", with further oxidation to {AgCl2(Cl2)}(-) followed by Cl2 release.

Electroless reduction of silver chloride precipitates for the preparation of highly sensitive substrates for surface-enhanced infrared absorption (SEIRA) measurements.

To prepare silver nanoparticles (AgNPs) on infrared-transmitting crystal for surface-enhanced infrared absorption (SEIRA) measurements, a new strategy is proposed and demonstrated using electroless reduction of preformed silver chloride (AgCl) particles. Silver chloride precipitates were formed using an additive of polyvinyl pyrrolidone (PVP) to vary the size and shape of the precipitates. After settling on germanium substrates, the preformed particles of AgCl were reduced electrolessly and spontaneously coagulated to AgNPs. The resulting AgNPs showed a multilayer structure, but the AgNPs were isolated, as shown by the lack of absorption-band distortion in the SEIRA measurements. Hence, the sensitivity and analyte-loading capacity for SEIRA measurements are improved significantly. To optimize the chemical deposition and electroless reduction method, we examined several parameters, including the concentrations of reagents during AgCl precipitation and the reaction time required in the deposition-reduction steps. We used para-nitrobenzoic acid (pNBA) to probe the intensity of the SEIRA effect for the prepared substrates. To better correlate the SEIRA performances with each variable, we examined the prepared substrates using a scanning electron microscope and SEIRA. The results indicate that two major morphologies of AgNPs are observed: nanoparticles and nanorods. The distributions of nanorods we observed were related to the procedures used to prepare the substrates. Based on SEIRA signals, we observed enhancement factors approaching three orders of magnitude compared to conventional transmission measurement. Also, based on the morphologies, the large signals were mainly caused by the formation of multilayers of non-percolated AgNPs.

A new silver based composite material for SPA water disinfection

A new composite material based on alumina (Al2O3) modified by two surface nanocoatings – titanium dioxide (TiO2) and silver (Ag) – was studied for spa water disinfection. Regarding the most common microorganisms in bathing waters, two non-pathogenic bacteria Escherichia coli (Gram-negative) and Staphylococcus epidermidis (Gram positive) were selected as surrogates for bacterial contamination. The bactericidal properties of the Al2O3–TiO2–Ag material were demonstrated under various operating conditions encountered in spa water (temperature: 22–37 °C, presence of salt: CaCO3 or CaCl2, high oxygen content, etc.). Total removal of 108 CFU mL−1 of bacteria was obtained in less than 10 min with 16 g L−1 of material. Best results were observed for both conditions: a temperature of 37 °C and under aerobic condition; this latest favouring Reactive Oxygen Species (ROS) generation. The CaCO3 salt had no impact on the bactericidal activity of the composite material and CaCl2 considerably stabilized the silver desorption from the material surface thanks to the formation of AgCl precipitate. Preliminary tests of the Al2O3–TiO2–Ag bactericidal behaviour in a continuous water flow confirmed that 2 g L−1 of material eliminated more than 90% of a 2.0 × 108 CFU mL−1 bacterial mixture after one water treatment recycle and reached the disinfection standard recommended by EPA (coliform removal = 6 log) within 22 h.

Synthesis and Thermal Studies of Chitin/AgCl Nanocomposite

Chitin/Silver chloride nanocomposite (Chitin/AgCl) has been successfully synthesized using Chitin, Lithium chloride (LiCl), Silver nitrate (AgNO3) and N,N-dimethyl acetamide (DMAc). Lithium chloride is used as the reactant to synthesis AgCl crystals during the precipitation of chitin from the solution. This method is based on the simultaneous formation of AgCl nanoparticles and precipitation of the Chitin, results homogeneous distribution of AgCl nanoparticles in chitin matrix. Synthesised nanocomposite is characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) studies, Differential scanning calorimetry (DSC) and Thermal gravimetric analysis (TGA). The experimental results confirmed the formation of Chitin/AgCl nanocomposite with high purity and improved thermal stability.

Simultaneous microwave-assisted synthesis, characterization, thermal stability, and antimicrobial activity of cellulose/AgCl nanocomposites

By means of a simultaneous microwave-assisted method and a simple chemical reaction, cellulose/AgCl nanocomposites have been successfully synthesized using cellulose solution and AgNO3 in N,N-dimethylacetamide (DMAc) solvent. The cellulose solution was firstly prepared by the dissolution of the microcrystalline cellulose and lithium chloride (LiCl) in DMAc. DMAc acts as both a solvent and a microwave absorber. LiCl was used as the reactant to fabricate AgCl crystals. The effects of the heating time and heating temperature on the products were studied. This method is based on the simultaneous formation of AgCl nanoparticles and precipitation of the cellulose, leading to a homogeneous distribution of AgCl nanoparticles in the cellulose matrix. The experimental results confirmed the formation of cellulose/AgCl nanocomposites with high-purity, good thermal stability and antimicrobial activity. This rapid, green and environmentally friendly microwave-assisted method opens a new window to the high value-added applications of biomass.

Tailoring Galvanic Replacement Reaction for the Preparation of Pt/Ag Bimetallic Hollow Nanostructures with Controlled Number of Voids

Here we report the synthesis of Pt/Ag bimetallic nanostructures with controlled number of void spaces via a tailored galvanic replacement reaction (GRR). Ag nanocubes (NCs) were employed as the template to react with Pt ions in the presence of HCl. The use of HCl in the GRR caused rapid precipitation of AgCl, which grew on the surface of Ag NCs and acted as a removable secondary template for the deposition of Pt. The number of nucleation sites for AgCl was tailored by controlling the amount of HCl added to the Ag NCs or by introducing PVP to the reaction. This strategy led to the formation of Pt/Ag hollow nanoboxes, dimers, multimers, or popcorn-shaped nanostructures consisting of one, two, or multiple hollow domains. Due to the presence of large void space and porous walls, these nanostructures exhibited high surface area and improved catalytic activity for methanol oxidation reaction.

Isolated Silver Intermediate of Gold Precatalyst Activation

AbstractThe silver chloride and gold chloride complex of the extremely sterically shielding N‐heterocyclic carbene ligand IPr** have been synthesized and characterized. Formally, eight methyl groups of IPr have been replaced by 4‐tert‐butylphenyl substituents, and two para‐methyl groups have been added. The world record for the ligand's buried volume (55.4 % for IPr**AuCl, and 56.7 % for IPr**AgCl) has been determined by single‐crystal X‐ray analyses. Reaction of IPr**AuCl with AgSbF6 in toluene yields AgCl and a cationic gold complex with toluene coordination. The same reaction in 1,2‐dichloroethane leads to precipitation of AgCl and an equilibrium of [IPr**Au]SbF6 and [IPr**AuClAg]SbF6. Single crystals of the latter were suitable for an X‐ray structure analysis, which reveal an Au–Cl–Ag triangle with an almost undisturbed IPr**–Au–Cl fragment and the coordination of two IPr** arenes to a silver cation. The structural parameters emphasize the role of NHC‐Au cations as highly electrophilic “soft protons”.

Syntheses of Au–Cu-rich AuAg(AgCl)Cu alloy and Ag–Cu-rich AuAgCu@Cu core–shell and AuAgCu alloy nanoparticles using a polyol method

Core–shell and alloy types of nanoparticles including Au, Ag, and Cu components were prepared by reducing mixtures of HAuCl4·4H2O, AgNO3, and Cu(OAc)2·H2O in ethylene glycol (EG) in the presence of poly(vinylpyrrolidone) (PVP) at 175 °C. At a HAuCl4·4H2O : AgNO3 : Cu(OAc)2·H2O molar ratio of 1 : 2 : 1, mixtures of Au–Cu-rich AuAg(AgCl)Cu alloy nanoparticles and AgCl precipitates were formed after 2.5–35 min heating. On the other hand, at a HAuCl4·4H2O : AgNO3 : Cu(OAc)2·H2O molar ratio of 0.0065 : 2 : 1, at which the formation of AgCl precipitate was suppressed, Ag–Cu-rich AuAgCu alloy particles were prepared via AuAgCu@Cu core–shell particles after 2.5–34 min heating. The growth mechanisms of AuAg(AgCl)Cu, AuAgCu@Cu, and AuAgCu particles were examined using TEM-energy dispersed X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES), and ultraviolet (UV)-visible (Vis)-near infrared (NIR) extinction spectral data. The time dependence of UV-Vis-NIR spectral data indicated that the Cu components of AuAg(AgCl)Cu and AuAgCu alloy particles retained good anti-oxidation properties about 1 month after preparation.