Silver Ions In Aqueous Solution Research Articles

Fabrication of a novel hydrophilic ion-imprinted polymer based on silica-modified magnetic graphene oxide as a sensitive sorbent for the fast separation of silver ions from aqueous media

This paper aimed to evaluate the co-precipitation preparation of a novel magnetic graphene oxide ion-imprinted polymer (IIP) for the recognition and separation of silver ions in aqueous solutions. The synthesis of this adsorbent was established by thermal copolymerization of 4-vinyl pyridine (4-VP) as a functional monomer, salen as a ligand, silver ions as a template ion, ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent, acetonitrile and chloroform as the solvents, 2,2-azobisisobutyronitrile (AIBN) as an initiator by coating on the surface of magnetic graphene oxide as a magnetic core. The prepared polymer was morphologically characterized by the use of several characterization techniques. A batch-wise adsorption investigation was carried out to determine favorable conditions for proper adsorption, likewise selectivity and reusability. The kinetics of the adsorption process was pseudo-second order and followed the Langmuir isothermal model. The maximum adsorption capacity was 77.6 ± 0.6 mg g−1 at a pH of 4. The involvement of other competing ions revealed that the adsorbent benefits from the selective property of the imprinted cavities.

Polymer-analogous transformations of poly(N-vinylpyrrolidone) to produce new complexing macromolecular systems

A new polymer-analogous transformations of poly(N-vinylpyrrolidone) was used to prepare new complex-forming macromolecular systems containing thiourea and thio-semicarbazone sites. Two variants of modification were realized, namely, the method including the preliminary in situ activation of nucleophilic centres of the polymer amide fragments with dimethyl sulfate followed by introducing nucleophilic agents into the system, and the method including partial hydrolysis of poly(N-vinylpyrrolidone) followed by the amide coupling. The obtained modified polymeric materials react with silver ions in aqueous solution.

СИНТЕЗ ТА АНТИМІКРОБНА АКТИВНІСТЬ КОЛОЇДНИХ РОЗЧИНІВ БІКОМПОНЕНТНИХ НАНОЧАСТИНОК Ag/CuO СТАБІЛІЗОВАНИХ РАМНОЛІПІДОМ

Despite the extremely high activity of researchers in the direction of green synthesis of nano-particles of silver, copper, as well as bimetallic nanoparticles Ag/Cu-NPs, the many aspects of the synthesis of nanoparticles based on silver and copper remain unexplored, in particular, the studies on the influence of the nature of biosurfactants on the characteristics are relevant obtained nano¬particles, in particular their size, shape, etc., as well as the influence of the morphology and compo¬sition of nanoparticles on their antimicrobial properties. Therefore, the purpose of this work was to synthesize colloidal solutions of bicomponent Ag/CuO-NPs nanoparticles of different composition and to investigate their antimicrobial activity. Bicomponent Ag/CuO nanoparticles of different composition were obtained by the method of coprecipitation of Ag+ and Cu2+ cations in solution of rhamnolipid. It was found that the process of formation of monocomponent CuO nanoparticles is completed within 2.5 hours but the reduction of silver ions in aqueous solutions of RL occurs within a few minutes. The obtained Ag/CuO-NPs were studied using UV-visible spectroscopy and the method of powder diffraction of X-rays. It was found that the absorption spectra of Ag/CuO-NPs solutions are characterized by two maxima at 280 and 410 nm, which correspond to the surface plasmon resonance bands of CuO and Ag-NPs, res-pectively. Based on the obtained data, it is reasonable to assume that the obtained Ag/CuO-NPs can form core-shell structures in which the role of the core will be played by silver surrounded by a CuO shell. Taking into account the prospects of using the nanoparticles based on silver and copper as antimicrobial agents for the plant protection, the antimicrobial activity of the synthesized Ag/CuO-NPs was investigated. The gram-negative bacteria-phytopathogens were used as test microorganisms, namely Agrobacterium tumefaciens, which is the causative agent of crown gall disease of a wide range of agricultural crops and Xanthomonas campestris, which is the causative agent of the "black rot" disease in cruciferous vegetables. The antimicrobial activity of the synthesized colloidal solutions of Ag/CuO was evaluated by the minimum inhibitory concentration values. The results of the studies of antimicrobial activity of the synthesized Ag/CuO colloidal solutions showed that the obtained preparations effectively inhibit the growth of phytopathogenic bacteria Agrobacterium tumefaciens and Xanthomonas campestris and it was found that the obtained drugs are more active against the Xanthomonas campestris.

A Green Approach for Micro Determination of Silver(I) in Water and Soil Samples Using Vitamin C

A cloud point extraction/solvation method (CPE-SM) based on the use of vitamin C as a chelating agent was developed for the separation and determination of silver in environmental samples. TritonX-100 was used to extract silver ions in aqueous solutions after forming solvation species with vitamin C in the presence of salting-out (0.5 mol L-1 KNO3) at 90 C for 10 minutes. This study evaluated the main parameters affecting the CPE-SM method, such as the kind and concentration of the salting-out, organic reagents, silver ion, temperature, heating time, and volume of surfactant. Under the optimized experimental factors, the calibration curve was linear in the range (0.1 -10 μg/L). The relative standard deviation (RSD) was 1.1-2.9% for n:5 at 1,4,9 μg L-1, a low limit of detection (LOD), and a limit of quantification (LOQ) of 0.035, 0.116 μg L-1 respectively. The accuracy of the method was evaluated by two independent techniques (flame atomic absorption spectrometry – FAAS, and spectrophotometry - using dithizone as a complexing agent). The CPE-SM technique was used to preconcentrate and determine the silver ions in river water, tap water, and soil samples, and the results were favorable and good.

Highly sensitive detection of mercury(II) and silver(I) ions in aqueous solution via a chromene-functionalized imidazophenazine derivative

In this work, we designed and synthesized a chromene-functionalized imidazophenazine-based fluorescent sensor (PS) which can detect mercury ions and silver ion in aqueous solution by different fluorescence behavior. When Hg2+ was added to the solution of PS, the fluorescent color of PS changed from yellow to green, and the emission peak was shifted from 543 nm to 511 nm. Upon the addition of Ag+, the fluorescence of PS was quenched. The detection limits of the PS for Hg2+ and Ag+ were calculated as 1.2 × 10−7 M and 3.6 × 10−8 M, respectively. In addition, the Ag+-coordinated non-fluorescent complex (PS-Ag+) could be used as new chemosensor for selective fluorescent turn-on detection of Hg2+ through competitive coordination in aqueous solution with a detection limit of 1.5 × 10−8 M.

Sorption Preconcentration Of Silver For Atomic Absorption Analysis And Antibacterial Properties Of The Acid-Modified Clinoptilolite – Ag Composite

Sorptive properties of the acid-modified Transcarpathian clinoptilolite towards Ag(I) were studied under dynamic conditions. It was found that the most effective acid-modifier is 1 M HNO3 solution. The sorption capacity value of H-clinoptilolite under the optimal conditions is 6.15 mg of Ag per 1 g of zeolite. The solid-phase extraction procedure with acid-modified clinoptilolite was used to pre-concentrate trace amounts of silver ions in aqueous solutions and then finally to determine them by the atomic absorption method. Due to the acceptable recoveries (≥ 98 %) and RSD values (2.3-4.7 %) for tap and lake water, the developed method can be successfully applied for the determination of trace amounts of silver ions in the presence of major components of water. It was established that the initial form of clinoptilolite has a better antibacterial effect against E. coli than the H-form. However, antagonistic activity against S. aureus was lower than against E. coli in both forms. The combination of different forms of clinoptilolite with Ag(I) increases their antibacterial activity.

A novel solid-phase extraction method for preconcentration of silver and antimicrobial properties of the Na-clinoptilolite–Ag composite

Sorptive properties of the Na-modified Transcarpathian clinoptilolite towards Ag(I) were studied under dynamic conditions. The sorption capacity value of Na-clinoptilolite under the optimal conditions is 7.46 mg Ag per 1 g of zeolite. Silver was quantitatively removed from the solid-phase extraction column with 0.1 M RbNO3 solution. The solid-phase extraction procedure with Na-clinoptilolite was used to preconcentrate trace amounts of silver ions in aqueous solutions to be finally determined by the atomic absorption method. It was established that the Na-form of clinoptilolite exhibits insignificant antimicrobial effect against E. coli and S. aureus. The doping of this form of clinoptilolite with silver increases the ability of this composite to suppress the growth of E. coli and S. aureus.

Specific Features of Interactions of Polyvinylpyrrolidone Molecules with Zinc and Silver Ions in Aqueous Solutions According to IR Spectroscopy Data

Aqueous solutions containing polyvinylpyrrolidone and zinc and silver nitrates are studied by IR spectroscopy. It is shown that introduction of zinc and silver nitrates into polyvinylpyrrolidone solutions leads to a shift of the polymer absorption bands to lower wavenumbers. The results obtained indicate the possibility of formation of complexes consisting of polymer molecules and metal ions.

Corn-derived dendrimer-like carbohydrate phytoglycogen nanoparticles as selective fluorescent sensor for silver ions

A dendrimer-like carbohydrate phytoglycogen (PG) extracted from corn was modified as a fluorescent nanocarrier via a simple method. Fluorescein was successfully linked to PG by covalent bonds through APTES as the bridge. NMR, XPS, UV, fluorescence and confocal microscopy validated the high feasibility and efficiency of the preparation of fluorescent phytoglycogen (F-PG). The morphology of F-PG was investigated by TEM and XRD analysis which showed amorphous nature and spherical or cauliflower-like shape with highly branched structures inside. The fluorescent carbohydrate nanoparticles inherited the high stability and excellent dispersibility in water, which was proved by DLS measurements. Furthermore, ratiometric response towards silver ions could be obtained from fluorescence spectroscopy in aqueous media without the need of adding organic solvents, with good linearity (R2 = 0.993) and high selectivity, indicating a great potential of applying this renewable biopolymer as a sensor for silver ions in aqueous solution.

Synthesis, dissolution, and regeneration of silver nanoparticles stabilized by tannic acid in aqueous solution

Silver nanoparticles (AgNPs), especially with small size, are easy to release silver ion in aqueous solution owing to various reasons, which would significantly affect the stability, properties, and application of AgNPs. In this paper, monodisperse AgNPs with small size of ca. 10 nm were successfully prepared based on solid-state reactions. Ascorbic acid (AA) was used as reductant and tannic acid (TA) was used both as reductant and stabilizer in this environmentally friendly reaction. The dissolution and regeneration of the as-prepared TA-AgNPs in pure water were investigated by UV−vis spectra, TEM observations, and differential pulse anodic stripping voltammetry. The results indicated that the TA-AgNPs showed a little higher dissolution than conventional PVP-coated ones with similar size. However, the dissolved silver ion in the TA-AgNPs aqueous solution could be recovered just by adjusting the pH of the solution, which could be attributed to the reductant performance of TA at alkaline conditions. After regeneration, some smaller nanoparticles appeared in TA-AgNPs aqueous solution, indicating that new nucleation formed and the dissolved silver ions were actually recovered to Ag0.

First report of silver ion recognition via a silatrane-based receptor: excellent selectivity, low detection limit and good applicability

This study involves the synthesis of a silatrane-based receptor using Knoevenagel condensation and click chemistry approach for the recognition of silver ions in aqueous solution.

Silver Nanoparticles: The Powerful Antidote for Bacterial Blight Disease of Pomegranate

Successful cultivation is difficult to pomegranate growers due to <i>Xanthomonas axonopodis</i> pv. punicae which cause bacterial blight disease to pomegranate has become serious threat. However, everyone is looking for solution; this problem is resolved by synthesizing silver nanoparticles by the reduction of silver ions in aqueous solutions with the help of green synthesis method. The causative agent was isolated from the infected pomegranate fruits and was tested with silver nanoparticles which are synthesized from leaf extracts of tulsi and neem; and it was found that silver nanoparticle from tulsi extract with 15 mM concentration showed maximum zone of inhibition 22 mm and 19 mm for neem, while at 1 mM concentration shows minimum. This study showed that synthesized silver nanoparticles are powerful weapon to control the growth of <i>Xanthomonas axonopodis</i> pv. punicae.<div><br></div>

A reusable bifunctional fluorescent sensor for the detection and removal of silver ions in aqueous solutions

In this work, a novel bifunctional fluorescent sensor (FQ) was developed for simultaneous detection and removal of Ag+ in aqueous solutions by grafting a naphthalimide-based fluorescent probe onto the surface of the mesoporous silica nanoparticles. FQ exhibited good selectivity towards Ag+ in water samples, and showed 2.5-fold enhancement of fluorescence intensity with the addition of Ag+. Meanwhile, FQ showed a very good linearity at a low concentration of Ag+ with a detection limit of 7.2 × 10−6 M. In addition, FQ can also serve as an adsorbent for the removal of Ag+ in water samples with the maximal adsorption capacity of 14.8 mg g−1. FQ can be regenerated easily by modulating the pH value of the aqueous solution, and can be recycled at least eight times. All results demonstrate that FQ has potential applications for the detection and removal of Ag+ in aqueous samples.

Preparation of Fluorescent Thiol Group‐Functionalized Silica Microspheres for the Detection and Removal of Silver Ions in Aqueous Solutions

We demonstrate that silica microspheres can act as a sensitive fluorescent sensor and adsorbent of Ag+ in aqueous media. These thiol‐functionalized silica microspheres are doped with quantum dots (QDs) using organosilane chemistry in a one‐step preparation. Ligand exchange takes place between the thiolated organosilane and acid‐capped QDs, making the doping easy. Ag+ adsorption by the silica microspheres causes the decrease of fluorescence intensity of the QDs. The detection limit for Ag+ is found to be 10 μmol/L. The abundance of thiol groups on the surface of the microspheres could effectively remove Ag+ through strong interaction. When microspheres with a diameter of 1.1 μm are used as the adsorbents, the adsorption capacity for Ag+ reached 102 mg/g. This excellent adsorption ability is due to the abundance of thiol groups that act as the active sites, facilitating the adsorption of the massive metal ions on the surface of the microspheres. Furthermore, the adsorption isotherm data follows the Freundlich model. The structure and content of the silica microspheres were investigated by scanning and high‐resolution transmission electron microscopy, energy dispersive X‐ray spectroscopy, and Raman analysis, and the fluorescence properties were characterized by fluorescence microscopy.

Triazole-imidazole (TA-IM) derivatives as ultrafast fluorescent probes for selective Ag+ detection.

1,2,3-Triazole-imidazole derivatives (TA-IM) were prepared as fluorescent probes for silver ion detection. The design principle is the incorporation of an intramolecular H-bond between the imidazole and triazole moiety that enables a co-planar conformation to achieve fluorescence emission in the UV-blue range. Screening of different metal ions revealed excellent binding affinity of this new class of compounds toward silver ions in aqueous solution. The novel probe provided ultrafast detection (<30 s) even for a very low concentration of silver ions (in the nM range) with good linear correlation, making it a practical sensor for detection of silver ions.

Control of Bacterial Blight Disease of Pomegranate Using Silver Nanoparticles

Successful cultivation is difficult to pomegranate growers due to Xanthomonas axonopodis pv. punicae which cause bacterial blight disease to pomegranate has become serious threat. However, everyone is looking for solution; this problem is resolved by synthesizing silver nanoparticles by the reduction of silver ions in aqueous solutions with the help of green synthesis method. In the present study the causative agent was isolated from the infected pomegranate fruits and was tested with silver nanoparticles which are synthesized from leaf extracts of Tulsi, Neem, Tridax and Drumstick at variable concentrations and it was found that silver nanoparticle containing Tulsi extract with 15 mM concentration showed maximum zone of inhibition (22 mm), then Tridax (20 mm), Neem (19 mm) and Drumstick (18 mm) while at 1 mM concentration it shows minimum. The bioreduction was tested by using UV-Vis Spectrophotometer. This study showed that by using synthesized silver nanoparticles we successfully controlled the growth of Xanthomonas axonopodis pv. Punicae. They can be used in the field of medical as well as in the management of plant diseases

Polyethylenimine complexes with silver ions in aqueous solutions as precursors for synthesis of monodisperse silver iodide particles

The conditions of formation and composition of polyethylenimine complexes with silver ions in aqueous solutions are found. The complex is formed according to the model of a uniform distribution of ions throughout the macromolecule, and the composition of the complex may vary depending on pH of the medium. The size parameters are determined and the volume fractions of polyethylenimine macromolecular coils in solution are calculated. The synthesis of silver iodide particles is carried out under conditions where the silver ions are bound in the complex with polyethylenimine macromolecules and are distributed homogeneously over the volume of solution. The use of the polyethyleneimine complex with silver ions as a precursor of silver iodide allows the preparation of particles 1.2 nm in diameter with a narrow size distribution.

Fabrication of silver nanoparticles from silver salt aqueous solution at water-glass interface by visible CW laser irradiation without reducing reagents

Abstract We have investigated the excitation wavelength and intensity dependencies of fabrication of silver nanoparticles (Ag NPs) on a glass substrate through the laser-induced photoreduction of silver ions in aqueous solution. It was found that the nucleation of Ag NPs could occur not in an aqueous solution of silver nitrate but at a water-glass interface without any reducing reagents. The nucleation could be triggered by photoexcitation at visible to Near-IR wavelength regions where the silver nitrate solution has no absorption band. From the excitation wavelength dependence using five CW lasers at 325, 442, 532, 690, and 1064 nm, it has been presumed that one-photon absorption of unique surface chemical species such as silver oxide (Ag 2 O) on the glass substrate is responsible for the reaction leading to the nucleation. Numerical simulation of a single Ag NP and a Ag@Ag 2 O core-shell NP on the basis of Mie theory revealed the photoproducts consists of Ag, but not Ag 2 O.

Solid phase extractive preconcentration of silver from aqueous samples and antimicrobial properties of the clinoptilolite–Ag composite

Sorptive properties of the Transcarpathian clinoptilolite compared to Ag(I) were studied in a dynamic way. The sorptive capacity value of clinoptilolite under the optimal conditions is 11.7 mg of Ag per 1 g of zeolite. The solid-phase extraction procedure with natural clinoptilolite thermally activated at 550℃ was used to preconcentrate trace amounts of silver ions in aqueous solutions to be finally determined by the atomic absorption method. It was established that the Ag–clinoptilolite composite has a powerful antimicrobial effect against gram-negative bacteria and yeasts as well as affects significantly vital activity of Staphylococcus aureus.

Iron oxide nanoparticles coated with green tea extract as a novel magnetite reductant and stabilizer sorbent for silver ions: Synthetic application of Fe3O4@green tea/Ag nanoparticles as magnetically separable and reusable nanocatalyst for reduction of 4‐nitrophenol

Green tea extract having many phenolic hydroxyl and carbonyl functional groups in its molecular framework can be used in the modification of Fe3O4 nanoparticles. Moreover, the feasibility of complexation of polyphenols with silver ions in aqueous solution can improve the surface properties and capacity of the Fe3O4@green tea extract nanoparticles (Fe3O4@GTE NPs) for sorption and reduction of silver ions. Therefore, the novel Fe3O4@GTE NPs nano‐sorbent has potential ability as both reducing and stabilizing agent for immobilization of silver nanoparticles to make a novel magnetic silver nanocatalyst (Fe3O4@GTE/Ag NPs). Inductively coupled plasma analysis, transmission and scanning electron microscopies, energy‐dispersive X‐ray and Fourier transform infrared spectroscopies, and vibrating sample magnetometry were used to characterize the catalyst. Fe3O4@GTE/Ag NPs shows high catalytic activity as a recyclable nanocatalyst for the reduction of 4‐nitrophenol at room temperature.