Precipitation Of AgCl Research Articles

Preparation of ionic liquid-immobilized siloxane membranes by vapor-phase transport and anion exchange

Using the sol-gel method, we developed ionic liquid (IL)-immobilized siloxane membranes from ionic alkoxysilanes (silylated ILs). The developed membranes were adapted for the separation of inorganic and organic gases and organic liquid mixtures. In this study, we developed a new method for preparing IL-immobilized siloxane membranes using vapor-phase transport and anion exchange techniques. First, a siloxane membrane containing chloropropyl groups was prepared in a porous Al2O3 tube. The membrane was brought into contact and reacted with 1-methylimidazole vapor at 353 K. AgCl precipitation, and Cl 2p3/2 X-ray photoelectron spectroscopy revealed that the chloropropyl group was successfully converted into an imidazolium-type IL structure. Next, the membrane was immersed in aqueous HN(SO2CF3)2 to exchange the anion from Cl− to (CF3SO2)2N−. The change in permselectivity through the membranes before and after the vapor-phase transport and anion-exchange treatments was confirmed by steam/H2 and toluene/N2 separation tests. The developed techniques exhibit excellent potential for preparing a wide variety of IL-immobilized siloxane membranes.

Catalytic selective separation of chloride ions from acidic wastewater

A new two-step technique was developed for selective separation of chloride ions from acidic aqueous solutions. The process is operated at ambient temperature and pressure, and it is powered by H2 gas and atmospheric oxygen. The Pt-Ag-AC catalyst comprises activated carbon (AC) loaded with platinum (Pt) nano size crystals and metallic silver (Ag) particles. The aeration of acidic chloride solution results in the oxidation of Ag0 to Ag+, which in turn reacts with chloride ions to form an insoluble AgCl precipitate on the catalyst. The regeneration of the Pt-AgCl-AC is performed by hydrogenation, that leads to reduction of AgCl into Ag0, followed by the release of Cl− ions. The process was studied in a batch mode system using acidic NaCl-H2SO4 solutions (500 mgCl/L, [H2SO4]0 = 0.5 M) and Pt-Ag-AC made of granular activated charcoal. The carbon was loaded with 0.5 %Pt and 3.22, 6.25 or 9.09 % of metallic silver. A maximal chloride adsorption capacity of 16.31 mgCl/g was recorded. Full (100 %) separation of Cl− ions from NaCl solutions with [Cl−]0 = 200 mg/L and [H2SO4]0 = 0.5 M was demonstrated.

Boosting cisplatin chemotherapy by nanomotor-enhanced tumor penetration and DNA adducts formation

Despite many nano-based strategies devoted to delivering cisplatin for tumor therapy, its clinical benefits are compromised by poor tissue penetration and limited DNA adducts formation of the drug. Herein, a cisplatin loading nanomotor based janus structured Ag-polymer is developed for cisplatin delivery of deeper tissue and increased DNA adducts formation. The nanomotor displayed a self‐propelled tumor penetration fueled by hydrogen peroxide (H2O2) in tumor tissues, which is catalytically decomposed into a large amount of oxygen bubbles by Ag nanoparticles (NPs). Notably, cisplatin could elevate the intracellular H2O2 level through cascade reactions, further promote the degradation of Ag NPs accompanied with the Ag+ release, which could downregulate intracellular Cl− through the formation of AgCl precipitate, thereby enhancing cisplatin dechlorination and Pt–DNA formation. Moreover, polymer can also inhibit the activity of ALKBH2 (a Fe2+-dependent DNA repair enzyme) by chelating intracellular Fe2+ to increase the proportion of irreparable Pt–DNA cross-links. It is found that deep tissue penetration, as well as the increased formation and maintenance of Pt–DNA adducts induced by the nanomotor afford 80% of tumor growth inhibition with negligible toxicity. This work provides an important perspective of resolving chemotherapeutic barriers for boosting cisplatin therapy.Graphical

Regular-Type Liesegang Pattern of AgCl in a One-Dimensional System.

The Liesegang phenomenon can be used for micro- and nanofabrication processes to yield materials with periodic precipitation of diverse types of materials. Although there have been several attempts to control the periodicity of the Liesegang patterns, it remains unclear whether the periodic precipitation of AgCl in gel medium causes regular- or revert-type patterns. To confirm the periodicity of the AgCl pattern, we conduct one-dimensional experiments under various ion concentration conditions. From microscopic observations, three different precipitation modes were observed, i.e., continuous precipitation with a sharp front, periodic precipitation and continuous precipitation with a gradual front. For these three modes, numerical analyses of the pattern geometry are performed for the periodic precipitation. It was confirmed that the regular-type pattern appeared for all concentration conditions conducted in the present experiments. Furthermore, the pattern was found to obey the spacing law and the Matalon–Packter law. From our experiments, we concluded that AgCl forms regular-type Liesegang patterns, regardless of the dimension of diffusion.

Facile construction of Z-scheme AgCl/Ag-doped-ZIF-8 heterojunction with narrow band gaps for efficient visible-light photocatalysis

It is of great importance to fabricate photocatalyst with high photocatalytic activity, and the formation of Z-scheme heterojunction photocatalyst has been proved to be an effective way to restrain the recombination of photo-induced carriers. In this work, Z-scheme AgCl/Ag-doped-ZIF-8 heterojunction is synthesized via a two-step process involving appropriate amount of cationic Ag ion doping into the imidazole ring of ZIF-8 framework and the precipitation of AgCl onto this Ag-doped-ZIF-8. The successful doping of ZIF-8 which decreases the band gap energy, enhances the light harvesting. Besides, the separation efficiency of photo-induced carriers is further improved due to the formation of Z-scheme AgCl/Ag-doped-ZIF-8 heterojunction, which is confirmed by photoelectrochemical experiments. As a result, the as-prepared AgCl/Ag-doped-ZIF-8 photocatalyst possesses excellent photocatalytic activity under visible light illumination. This work will provide a novel perspective for the design and construction of Z-scheme heterojunction for highly efficient photocatalysis.

Recovery of Silver from Solar Panel Waste: An Experimental Study

The aim of this study was to develop a recycling process to recover silver metal from solar panel waste. Experimental procedure consisted of mechanical/physical separation, leaching of silver from silicon wafer and precipitation to retrieve silver chloride (AgCl) precipitate. The precipitated AgCl was reduced to silver precipitate form which was subsequently heated up to produce silver metal. The leaching process was first conducted by using 4 M of nitric acid for 24 hrs. The silver-containing leached solution would then be added by sodium chloride solution to precipitate AgCl. The precipitate was filtrated out from the solution and was rinsed with water ready for further step. The rinsed precipitate was dissolved in water, then sucrose and sodium hydroxide were added to achieve precipitated silver. Finally, the precipitated silver was burned with acetylene gas to finally obtain silver metal. Base on the experiment the purity of silver metal of 99.98% can be achieved and by considering recycling of solar panel of 1,000 kg the recycling product of pure silver of 0.23 kg could be acquired.

TiO2-supported Au-Ag plasmonic nanocatalysts achieved by plasma restructuring and activation

Plasmonic Au-Ag/TiO2 bimetallic nanocatalyst is regarded as a promising visible-light (VL) photocatalyst due to its wide light absorption and potentially enhanced activity. For its preparation, Au precursors usually contain Cl and co-impregnation/co-deposition suffers from AgCl precipitation, and consequently Au and Ag have to be sequentially supported. However, Au and Ag species of the sequential preparation are individually isolated and difficult to be homogeneously mixed. Here we report an Au-Ag plasmonic nanocatalyst achieved by plasma restructuring and activation from the sequential preparation. The isolated cationic Au and Ag species on the sequentially-prepared Au-Ag/TiO2 sample are restructured to be homogeneously mixed and highly activated by O2 plasma, which can be partially auto-reduced to Au-Ag bimetallic nanoparticles within the induction period of a few minutes in VL photocatalytic oxidation of CO. The Au-Ag plasmonic nanocatalyst exhibits a strongly enhanced activity in the VL photocatalytic reaction. The contribution of O2 plasma treatment and the enhancement mechanism for the Au-Ag plasmonic nanocatalyst are disclosed.

Plasmonic Ag as electron-transfer mediators in Bi2MoO6/Ag-AgCl for efficient photocatalytic inactivation of bacteria

Solar-driven photocatalysis undoubtedly represents one of the most promising alternative water disinfection technologies, however, its practical application is still restrained by the fast recombination of carriers. To overcome this limitation, plasmon-induced photocatalytic processes have gained attention due to their extended optical absorption and enhanced charge separation when metal nanoparticles act as co-catalysts. In this work, to enhance the photocatalytic disinfection of Bi2MoO6/AgCl, the formation of plasmonic Ag nanoparticles as electron transfer mediators was promoted on the surface of Bi2MoO6 photocatalysts. Specifically, the co-modified Bi2MoO6/Ag-AgCl photocatalysts were synthesized via a two-step process involving the precipitation of AgCl and photo-reduction of Ag on the Bi2MoO6 surface. It was found that Bi2MoO6/Ag-AgCl photocatalysts exhibited higher photocatalytic disinfection activity under visible light irradiation than those of Bi2MoO6 and Bi2MoO6/AgCl. The photocatalytic mechanism of Bi2MoO6/AgCl could be attributed to the excellent synergistic effect of Ag and AgCl, where plasmonic Ag nanoparticles promote light absorption and work as electron-transfer mediators to transfer electrons from Bi2MoO6 to AgCl, meanwhile AgCl work as interfacial catalytic active sites to product free radicals based on the powerful characterizations, such as PL spectra, photoelectrochemical methodology and theoretical calculations. This work may provide new insights to employ synergistic effect of heterogeneous photocatalysts for improving the catalytic activities in water purification.

Development and Investigation of Lanthanum Sulfadiazine with Calcium Stearate and Epoxidised Soyabean Oil as Complex Thermal Stabilizers for Stabilizing Poly(vinyl chloride).

Lanthanum sulfadiazine (LaSD) was synthesized from sulfadiazine and lanthanum nitrate using water as solvent under alkaline conditions, and was used as a novel rare earth thermal stabilizer to stabilize poly(vinyl chloride) (PVC). The structure of LaSD was characterized by elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR) and thermo- gravimetric analysis (TGA). The influence of lanthanum sulfadiazine with calcium stearate (CaSt2) and epoxidized soybean oil (ESBO) on stabilizing PVC was studied by using the Congo red test, oven discoloration test, UV-vis spectroscopy and thermal decomposition kinetics. The results showed that the addition of LaSD as a thermal stabilizer can significantly improve the initial whiteness and long-term stability of PVC. In addition, the synergies between LaSD, ESBO, and CaSt2 can provide outstanding improvement in the long-term thermal stability of PVC. When the ratio of LaSD/ESBO/CaSt2 is 1.8/0.6/0.6, its thermal stability time is 2193 s which is the best state for stabilizing PVC. Furthermore, comparing the reaction energy (Ea) and the variations in the conjugate double bond concentration in PVC samples, the order of thermal stability of PVC was PVC/LaSD/ESBO/CaSt2 > PVC/LaSD/ESBO > PVC/LaSD. The thermal stability mechanism of LaSD on PVC was studied by the AgCl precipitation method and FTIR spectrum. The results showed that the action of LaSD on PVC was achieved through replacing unstable chlorine atoms and absorbing hydrogen chloride.

Reactions of the organoplatinum complex [Pt(cod) (neoSi)Cl] (neoSi = trimethylsilylmethyl) with the non-coordinating anions SbF6– and BPh4–

Abstract Reactions of the organoplatinum complex [Pt(cod)(neoSi)Cl] (neoSi = (trimethylsilylmethyl) with the Ag(I) salts of oxo or fluoride containing anions A– = NO3 –, ClO4 –, OTf – (trifluoromethanesulfonate) and SbF6 – lead to the desired abstraction of the chlorido ligand and precipitation of AgCl. However, further reaction of the resulting Pt complexes [Pt(cod)(neoSi) (solvent)]+ with diverse N-heterocyclic ligands L such as pyridines, caffeine, and guanine did not yield the targeted complexes [Pt(cod)(neoSi)(L)](A) in most of the cases, but to extensive decomposition yielding [Pt(cod)(Me) (solvent)]+, thus transforming the neoSi into a methyl ligand. A detailed study on the reaction with SbF6 – combining DFT calculations with NMR and MS revealed that Pt catalysed decomposition of SbF6 ‒ and fluorination of the neoSi silicon atom leading to FSiMe3. When reacting the parent complex with Ag(BPh4), the arylated derivative [Pt(cod)(neoSi)(Ph)] was obtained and characterised by multinuclear NMR, MS and single crystal XRD.

Antibacterial activity of Ag nanoparticle-containing hydroxyapatite powders in simulated body fluids with Cl ions

Abstract In vitro dissolution and antibacterial activity of Ag nanoparticle-containing hydroxyapatite (HA) powders (AgNPHAP) synthesized by precipitation method were evaluated in this study. AgNPHAP were immersed in Tris-HCl solution with 30 mM Cl ions to estimate the in vitro dissolution behavior. The amount of Ag ions in Tris-HCl solution first increased and then decreased because Ag ions reacted with Cl ions to form AgCl. The antibacterial activity of AgNPHAP increased with increasing amounts of AgNPs attached to the HA powders in both 1/500 nutrient broth (NB) and undiluted NB solutions, which had Cl ion concentrations of 0.2 and 100 mM, respectively. These results indicate that HA powders as Ag nanoparticle carriers can effectively prevent bacterial infections despite AgCl precipitation, even under simulated biological conditions such as in undiluted NB solution.

"Weakly Ligated, Labile Ligand" Nanoparticles: The Case of Ir(0) n ·(H+Cl-) m.

It is of considerable interest to prepare weakly ligated, labile ligand (WLLL) nanoparticles for applications in areas such as chemical catalysis. WLLL nanoparticles can be defined as nanoparticles with sufficient, albeit minimal, surface ligands of moderate binding strength to meta-stabilize nanoparticles, initial stabilizer ligands that can be readily replaced by other, desired, more strongly coordinating ligands and removed completely when desired. Herein, we describe WLLL nanoparticles prepared from [Ir(1,5-COD)Cl]2 reduction under H2, in acetone. The results suggest that H+Cl–-stabilized Ir(0)n nanoparticles, herein Ir(0)n·(H+Cl–)a, serve as a WLLL nanoparticle for the preparation of, as illustrative examples, five specific nanoparticle products: Ir(0)n·(Cl–Bu3NH+)a, Ir(0)n·(Cl–Dodec3NH+)a, Ir(0)n·(POct3)0.2n(Cl–H+)b, Ir(0)n·(POct3)0.2n, and the γ-Al2O3-supported heterogeneous catalyst, Ir(0)n·(γ-Al2O3)a(Cl–H+)b. (where a and b vary for the differently ligated nanoparticles; in addition, solvent can be present as a nanoparticle surface ligand). With added POct3 as a key, prototype example, an important feature is that a minimum, desired, experimentally determinable amount of ligand (e.g., just 0.2 equiv POct3 per mole of Ir) can be added, which is shown to provide sufficient stabilization that the resultant Ir(0)n·(POct3)0.2n(Cl–H+)b is isolable. Additionally, the initial labile ligand stabilizer HCl can be removed to yield Ir(0)n·(POct3)0.2n that is >99% free of Cl– by a AgCl precipitation test. The results provide strong support for the weakly ligated, labile ligand nanoparticle concept and specific support for Ir(0)n·(H+Cl–)a as a WLLL nanoparticle.

Stabilization of Colloidal Crystals Engineered with DNA.

A postsynthetic method for stabilizing colloidal crystals programmed from DNA is developed. The method relies on Ag+ ions to stabilize the particle-connecting DNA duplexes within the crystal lattice, essentially transforming them from loosely bound structures to ones with very strong interparticle links. Such crystals do not dissociate as a function of temperature like normal DNA or DNA-interconnected superlattices, and they can be moved from water to organic media or the solid state, and stay intact. The Ag+ -stabilization of the DNA bonds is accompanied by a nondestructive ≈25% contraction of the lattice, and both the stabilization and contraction are reversible with the chemical extraction of the Ag+ ions, by AgCl precipitation with NaCl. This synthetic tool is important, since it allows scientists and engineers to study such crystals in environments that are incompatible with structures made by conventional DNA programmable methods and without the influence of a matrix such as silica.

Analysis of 3H, 36Cl, 133Ba, 134Cs and 22Na from synthetic granitic groundwater: an in situ through diffusion experiment at ONKALO

A method for analyzing 3H, 36Cl, 22Na, 133Ba and 134Cs from simulated groundwater (SGW) samples was introduced. Gamma emitting radionuclides 22Na, 133Ba and 134Cs were measured by using an HPGe-detector. Beta emitting 3H and 36Cl were separated from gamma emitting 22Na, 133Ba and 134Cs. AgCl precipitation was used for the separation of 36Cl from SGW samples with yields of 98 ± 2%. 3H was separated by distillation with recoveries of 97 ± 3%. This method was used for the determination of activity concentrations of 3H, 36Cl, 22Na, 133Ba and 134Cs in SGW samples collected from an in situ through diffusion experiment.

Unimolecular Nucleophilic Substitution (SN1): Structural Reactivity Evidenced by Colored Acid–Base Indicators

The different reactivities between 1°, 2°, and 3° butyl chlorides by the unimolecular nucleophilic substitution (SN1) mechanism were easily observed at 60 °C by a solvolysis reaction in ethanol with ether formation. The hydrogen ion from the byproduct HCl reacted with an acid–base indicator such as methyl red to induce a color change. At room temperature, the addition of AgNO3 was used to detect the released chloride ion by AgCl precipitation. The reactivity order (3° > 2° ≫1°) was visually confirmed by both a color change in an indicator and precipitate formation by these safe, quick, and easy assays.

Quantitative Analysis of Major and Minor Elements in Lead-free Solder Chip by LA-ICP-MS.

A method was established for the quantitative analysis of the elements (Cu, Ag, Pb, and Sn) in solder samples by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), with Sn-based matrix matched standard solutions for defining the calibration curves. It was found that chloride-ion presented in commercially available Sn standard solution resulted in a precipitation of AgCl and caused the deterioration of the linearity of the calibration curve for Ag. Therefore, a laboratory-made chloride-free Sn solution was used to prepare Sn matrix matched standard solutions so as to ensure the stability of the elements including Ag. For the quantitative analysis of solder samples by LA-ICP-MS, the operating conditions of the LA instruments were set to obtain a fluence of over 12 J cm-2. This is mainly because of larger LA-induced elemental fractionations using a fluence of <10 J cm-2. The results for Ag, Cu, Pb, and Sn in a certified reference material (NMIJ CRM 8203-a) were close to, or in agreement with, the certified values, indicating that the present method was valid for the quantitative analysis of the elements in solder samples. In comparison to the certified values, relatively larger uncertainties were obtained for the analytical results by LA-ICP-MS, which could be attributed to the dependence on the homogeneity of the sample because the sample aliquots used for analysis were much smaller than those required for the traditional analytical procedures (i.e., sample quantity ratio of ca. 1:13000). Further improvement of the uncertainty might be obtained by using a larger sample quantity for the analysis by LA-ICP-MS so as to improve the representativeness of the sample.

Effect of polymer coating composition on the aggregation rates of Ag nanoparticles in NaCl solutions and seawaters

The aggregation behaviour of polymer-coated silver nanoparticles (AgNPs) was characterized in NaCl solutions, and in two seawaters of different salinities and dissolved organic matter (DOM) contents. Representative organic coatings i.e. tannic acid (TA), alginic acid (ALG), two gum Arabic samples (GAL and GAH), branched polyethylenimine (BPEI), and non-ionic surfactants (reference material NM-300K) were selected to cover a wide range of zeta-potentials. The stability in NaCl solutions, as determined from the rate of variation in hydrodynamic size within a timeframe of one hour, followed the order BPEI≫NM-300K≈GAL≫ALG≈TA≫GAH. In the seawater samples the order was NM-300K≈GAL≫ALG>GAH>TA≈BPEI, and only TA, GAL and NM-300K batches behaved as expected from the NaCl experiments. Remarkably, the BPEI sample showed the largest aggregation rate in the seawater sample with the highest DOM concentration (277μM C). The GAH sample displayed a non-monotonic variation in aggregation rate with NaCl concentration, apparently due to concomitant precipitation of AgCl. The results indicate that non-electrostatic stabilization mechanisms and DOM-coating interactions are important for the prediction of stability and persistence of polymer-coated AgNPs in seawater.

Synthesis, vibrational spectra and single-crystal structure determination of lithium tricyanomethanide Li[C(CN)3

Abstract The long-elusive structure of lithium tricyanomethanide Li[C(CN)3] has been determined on the basis of material synthesized via a metathesis reaction of Ag[C(CN)3] with LiCl in water driven by AgCl precipitation and subsequently recrystallization from methanol. Li[C(CN)3] crystallizes in the non-centrosymmetric orthorhombic space group Ima2 with the unit-cell parameters a=751.06(4), b=1059.75(6) and c=563.27(3) pm adopting a unique structure with planar [C(CN)3]− anions exhibiting nearly ideal trigonal planar D 3 h symmetry. The Li+ cations are coordinated by five independent tricyanomethanide anions forming a distorted square pyramid with Li–N distances between 202 and 249 pm. The vibrational frequencies were also determined and along with other properties of Li[C(CN)3] compared with those of related compounds.

Magnifying Opportunities in Mg Batteries through Metastability

In the March issue of Chem, Andrews, Banerjee, and colleagues devise a clever strategy to synthesize a metastable one-dimensional polymorph of V2O5 and demonstrate reversible chemical and electrochemical Mg intercalation, with 90 mAh/g capacity retained after 50 cycles at an average cell potential of 1.65 V versus Mg metal. Their approach proves fruitful not only in identifying a new functional multivalent cathode material, but also in validating a general concept that metastable compounds can offer sufficiently low migration energies to support reversible cycling with multivalent ions.

Electrodeposition and Microstructure Characterization of Bimetallic Copper-Silver Films from the Methanesulfonic Acid Baths

In this work, the bimetallic copper-silver deposits with variable compositions are prepared by electrodeposition from the methanesulfonate bath containing chloride ions. The precipitation of AgCl in this acid copper-silver bath can be avoided by the introduction of thiourea (TU) as the complexing agent. The composition and microstructure of such deposits are significantly affected by the introduction of TU, silver ion concentration, and deposition potential. The silver content varying from 0.7 to 43 w/o (weight percent) in the deposits is effectively adjusted by the systematic variation in the electrolyte composition and current density. The microstructures, such as the silver content, grain size, crystalline preferential orientation, and roughness of this series of Cu-Ag deposits are systematically compared for future electronic applications.