中空载银纤维的银离子释放性能

银系纤维的抗菌性能主要来源于纤维表面或内部释放出来的银离子。采用电感耦合等离子体发射光谱仪对中空载银纤维的银离子释放性能进行测试分析,结果表明:中空载银纤维具有较为持久的释放性能,释放的银离子量随着浸渍时间的延长、浸渍温度的升高以及纤维本身载银量的增加而增加,随着纤维长度的增加而减少。     

Silver Extraction from Hydrochloric Acid Solutions with the Disulfide of Bis(2,4,4-trimethylpentyl)Dithiophosphinic Acid

Silver extraction from hydrochloric acid solutions with the disulfide of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (L) in toluene is described in this work. Based on the analysis of the extraction data, it was concluded that silver extraction is due to the formation of the compound AgCl?2L in the organic phase. An increase in the concentration of hydrochloric acid in the aqueous phase leads to a decrease in AgCl extraction because of the formation of non-extractable anionic complexes of silver. Solvent extraction efficiency decreases in the series octanol > decane > chloroform > toluene, which is due to the preferential solvation of the extracted complex by the solvent. A significant increase in the extraction of silver chloride with disulfide in the presence of octanol is caused by the strong interaction of the extracted compound and the alcohol, due to the chloride ion solvation by octanol. The possibility of using the disulfide for silver extraction from hydrochloric acid solutions containing metal impurities (Ni, Cu, Co, Zn, Fe (III), and Na) has been demonstrated. The degree of silver recovery in one stage was 98.62%, while the extractant showed high selectivity toward silver: the separation factors of silver over metal (β_Ag/_Me) ranged from 9000 to 30,000. Almost complete silver stripping from the organic phase was achieved when using a mixture of thiourea and sulfuric acid solutions. The extraction characteristics of the disulfide are much better as compared to that of the well-known commercially available extractant triisobutylphosphine sulfide. The disulfide of bis(2,4,4-trimethylpentyl)dithiophosphinic acid can be used for efficient extraction of silver from industrial hydrochloric acid solutions of different origin.     

Interaction of aqueous silver ions with the surface of pyrite

Electrochemical techniques (cyclic and linear sweep voltammetry) at rotating and stationary pyrite electrodes were used to study the interaction of pyrite with silver ions in nitrate supporting electrolyte, pH 3 and room temperature. At potentials just negative of the open circuit potential of pyrite, metallic silver was deposited by a nucleation-growth mechanism. Evidence for a surface ion exchange involving removal of Fe²⁺ from pyrite and replacement with silver ion was found (i) from an analysis of peak potentials for voltammograms taken after various immersion times and (ii) from the appearance of a peak at potentials negative to that for deposition of silver.     

Separation of the methyl esters of oleic,linoleic, and linolenic acids by column chromatography using cation exchange resin containing silver ion

By taking advantage of the tendency of silver ion to form complexes with unsaturated compounds, the methyl esters of oleic, linoleic, and linolenic acids have been cleanly separated in good yield by column chromatography. The silver ion was supported by means of a cation exchange resin; no silver was ever eluted from the column. Aqueous methanol, pure methanol, and ethanol saturated with butene-1 were employed as solvents.     

Rapid extraction of Cu(II) heavy metal from industrial waste water by using silver nanoparticles anchored with novel Schiff base

A new Schiff base named N-(4-hydroxy-3-methoxy benzylidine)-biphenyl-4-amine was synthesized from refluxing of equimolar quantity of vanillin and biphenyl-4-amine in alcoholic medium. Its composition, properties, and morphology were characterized by elemental analysis, FTIR (Fourier-transform infrared spectroscopy), UV–vis (ultraviolet visible spectroscopy), nuclear magnetic resonance spectroscopy, and mass spectral studies. Then, silver nanoparticles were synthesized by chemical reduction method and characterized by scanning electron microscope, UV–vis, FTIR, and mass spectra. The silver nanoparticles are then trapped with Schiff base by suitable method. The metal ion was analyzed by atomic absorption spectroscopy. Sugarcane bagasse (SCB) was used as solid phase for the removal of heavy metal from industrial waste water. Activation of solid phase was done with the base and acid, respectively. The Ag nano@Schiff base was adsorbed on the SCB. The effects of several parameters that affect the adsorption of Cu(II) metal ion including initial metal ion concentration, contact time, Schiff base weight, and pH were analyzed.     

双硫腙萃取分离原子吸收光谱法测定铅电解液中微量银含量

采用HCl—NaCl处理铅电解液,将银转为可溶性配位离子,用EDTA掩蔽基体和少量其他干扰元素,于pH=5～6的乙酸钠缓冲液中,用0.002%双硫腙—四氯化碳萃取银,然后用0.5mol/L的HCl—1%NaCl反萃取液反萃取,水相原子吸收分光光度法测定。方法流程较短,操作简单,回收率在95%以上。     

聚乙二醇在银粉制备中的应用

以乙醇为溶剂,PVP为保护剂,研究非离子表面活性剂聚乙二醇在银粉制备过程中的分散作用,并采用扫描电镜(SEM)和X射线衍射等对还原产物进行形貌观察和结构表征。结果表明:PEG对制备样品的纯度、分散性和颗粒大小有着重要的影响。在一定聚合度范围内,聚乙二醇相对分子质量大,分散效果好。采用PEG-400分散剂可制备出高分散、窄粒级的超细银粉。随着聚合度的增大,聚乙二醇在乙醇中溶解度下降,降低了其分散性能。     

载银煤/LLDPE抗菌复合材料

采用固-液吸附及熔融挤出相结合的方法制备一种新型的栽银煤/LLDPE抗菌复合材料(ACCPE).利用现代分析测试手段如IR、XRD、SEM对制备的复合材料进行表征.探讨复合材料的机械性能、流变性能、Ag~+释放特性及抗菌性能.结果表明:复合材料具有良好的机械性能、加工性能和抗菌性能,并且在大肠杆菌的抗菌实验中,Ag~+与煤显示出良好的加合作用.     

Selective silver ion adsorption onto mesoporous graphitic carbon nitride

A 3D cubic structure of mesoporous graphitic carbon nitride (3D-g-CN) was fabricated by nano casting using the mesoporous silica hard template KIT-6. The abundant intrinsic amine functionalities of 3D-g-CN were applied as a selective adsorbent for silver ions using the unique affinity of silver and amine functionalities. The large surface area of 3D-g-CN resulted in increased amine functionalities at the surface and enabled it to form complexes with silver ions. As a result, almost 400 mg/g of silver ion could be removed from 100 mM of initial solution at 293.15 K. The isotherm of silver ion adsorption onto 3D-g-CN was described by the Freundlich and Sips models and indicated heterogeneity of the adsorbent surface. Thermodynamic parameters determined from temperature dependent isotherms were verified by the endothermic silver ion adsorption process of 3D-g-CN. The adsorption capacity of silver ion on 3D-g-CN was maintained during several reuses without a significant decrease in capacity. Overall, the results indicate that 3D-g-CN has intrinsic amine functional groups with a large surface area and could therefore be utilized as an efficient selective adsorbent of silver ions for water purification.     

Characterization of silver catalysts for the oxidation of methanol

The selection of a silver catalyst system for further study was determined on a basis of cost and its ability to oxidize formaldehyde selectively. In addition a silver catalyst can provide a low light off temperature for the conversion of methanol to carbon dioxide and water vapor. Silver catalysts were prepared by the deposition of solutions of silver nitrate or silver chloride on gamma alumina washcoat supported on cordierite monolith. These silver catalysts were characterized by a variety of analytical techniques including TEM, SEM, EMP, STEM, XRF, XRD and FTIR.It is concluded that the best silver catalyst is prepared by deposition of silver from a solution of silver ammnonium chloride onto a cordierite supported high surface area gamma alumina washcoat, drying at 100°C in air, followed by reduction in flowing 3% H₂ in N₂ at 500°C for 4 h. This procedure will produce a silver catalyst with highest activity, largest retention and most uniform distribution of silver. The procedure also retains the concentration of silver and the gamma phase of alumina at temperatures as high as 1000°C in air for as long as 6 h.Due to the inability of normal TEM imaqing modes to obtain silver particle size information in the presence of the small gamma alumina washcoat particles a model system was made to test the ability of a dedicated STEM to furnish that information. The model system consisted of silver particles in the range of 1 to 50 nm which had been evaporated onto a uniform thin film of alumina. High resolution X-ray maps obtained from the model system demonstrate the ability to determine location and size of silver particles > 5 nm.A number of catalysts containing noble and base metals supported on gamma alumina washcoat on a cordierite monolith have also been studied. Laboratory flow reactor studies and chassis dynamometer studies using a Mercury Lynx modified to burn neat methanol have shown the following order of activity for conversion of methanol burned in experimental or engine exhaust gas: Pd > Ag > Pt + Rh > CuO + ZnO + Cr₂O₃ > Ni.     

Polyamide/silver antimicrobials: effect of crystallinity on the silver ion release

Polyamide/silver (PA/Ag) composite materials are regarded as potential antimicrobials by virtue of their efficacy to release the Ag⁺ ions in an aqueous medium. The effects of the matrix crystallinity on the Ag⁺ ion release characteristics of PA/Ag composites are discussed. It is found that matrix crystallinity is very decisive for the silver ion releasing properties and hence the antimicrobial efficacy of silver‐based antimicrobial polyamides. The crystallinities of the composites were evaluated using differential scanning calorimetry. The silver ion release characteristics of these composites were measured by anode stripping voltammetry. Silver ion release was higher in systems possessing lower degrees of crystallinity. Water‐diffusion characteristics of the composites control the silver ion release. The effect of crystallinity on silver ion release rate depends on the time of soaking of the specimens in water. Copyright © 2005 Society of Chemical Industry     

Determination of the Optimal Conditions for Synthesis of Silver Oxalate Nanorods

In this study, an orthogonal array design (OAD), OA₉, was employed as a statistical experimental method for the controllable, simple and fast synthesis of silver oxalate nanorods. Ultrafine silver oxalate rods were synthesized by a precipitation method involving the addition of silver ion solution to the oxalate reagent. The effects of reaction conditions, i.e., silver and oxalate concentrations, flow rate of reagent addition and temperature, on the diameter of the synthesized silver oxalate rods were investigated. The effects of these factors on the width of the silver oxalate rods were quantitatively evaluated by the analysis of variance (ANOVA). The results showed that silver oxalate nanorods can be synthesized by controlling the silver concentration, flow rate and temperature. Finally, the optimum conditions for the synthesis of silver oxalate nanorods by this simple and fast method were proposed. The results of ANOVA showed that 0.001 mol/L silver ion concentration, 40 mL/min flow rate for the addition of the silver reagent to the oxalate solution and 0 °C temperature are the optimum conditions for producing silver oxalate nanorods with 107 ± 45 nm width.     

Separation of Palladium and Silver from a Nitric Acid Solution by Liquid Surfactant Membranes

Abstract

The recovery of palladium from a nitric acid solution containing silver has been conducted by application of liquid surfactant membranes (LSMs) containing LIX 860, a β-hydroxyoxime, as a mobile carrier in a stirred tank. The extraction equilibria of palladium and silver using several different extractants were also studied. Palladium was selectively extracted from a silver-containing liquor with LIX 860 while it was also observed that both palladium and silver were extractable with a sulfur-containing extractant. The recovery of palladium with LIX 860 was selectively achieved by using perchloric acid solution as the LSM internal phase dosed with thiourea. In the LSM operation, the effects of several chemical parameters on the selective recovery of palladium were studied. The use of hydrochloric acid as an internal receiving phase prevented the transport of silver into the emulsion due to the formation of silver chloride in the external feed solution. Commercially available Span 80 was found suitable for the selective extraction of palladium as a surfactant in LSM operation. Under optimum conditions, palladium was successfully separated from silver and concentrated into a receiving phase in W/O emulsions.     

Influence of the Eu2+ on the Silver Aggregates Formation in Ag+–Na+ Ion‐Exchanged Eu3+‐Doped Sodium–Aluminosilicate Glasses

Europium‐doping sodium–aluminosilicate glasses are prepared by melt‐quenching method, in which europium ions were spontaneously reduced from their trivalent to divalent state. The silver was introduced into glasses by Ag⁺–Na⁺ ion exchange and the interactions between europium ions and silver species were investigated. Owing to energy transfer (ET) from Ag⁺/silver aggregates to Eu³⁺, significant enhancements of Eu³⁺ emission were observed for 285/350‐nm excitation, respectively. The divalent europium ions promote the formation of silver aggregates in the process of ion exchange.     

Selective Extraction of Precious Metal Ions with Novel Trident Molecules Containing Pyridyl Groups

Trident molecules containing pyridyl groups have been prepared for use as novel extraction reagents to investigate their physicochemical properties for dissolution into the aqueous phase and their ability, together with their corresponding monomeric analogues, to extract precious metal ions. Differences in their behavior were related to the pK _a values of the trident molecules and the position of the nitrogen atom in the pyridyl groups. The trident molecules exhibit the ability to selectively extract silver from mixtures of other precious metals. The extraction mechanism and the coordination site of the silver ion with a 2-pyridyl derivative were determined by slope analysis and peak shift of the ¹H-NMR spectra of the extraction reagent before and after silver loading.     

高浓度∑Fe对硝酸银滴定法测定Cl-干扰的消除

采用硝酸银滴定法测定含高浓度铁离子溶液中的Cl-时,需要调整pH到6.5~10.5,产生氢氧化铁与氢氧化亚铁沉淀,影响滴定终点的判定,导致分析结果不准确。本研究在含不同高铁浓度模拟溶液中加入氢氧化铝胶体洗涤出铁离子,再用硝酸银滴定法分析Cl-浓度,结果显示在Cl-浓度20 mg/L时,相对偏差小于5%,浓度为200 mg/L时,相对偏差最大为1.03%,并把该方法应用在分析花岗岩铀矿浸出液中的Cl-浓度,与采用选择氯离子电极法分析结果对比,结果表明了这两种方法的分析结果相差不大。因此该方法消除高铁对硝酸银滴定法分析氯离子是可行的。     

The chemistry involved in the loading of silver(I) into poly(amic acid) via ion exchange: A metal-ion-induced crosslinking behavior

Metal-ion-induced crosslinking of poly(amic acid) (PAA) was observed in the incorporation of silver ions into PAA through ion exchange. Studies on the interaction of silver ions with 3,3′,4,4′-benzophenonetetracarboxylic acid/4,4′-oxidianiline (BTDA/ODA)-based PAA suggest that the ion exchange reactions between poly(amic acid) and silver ions are not so simple as what we generally believed. It involves not only the formation of silver carboxylate but also the generation of diversified silver chemical entities arising from the strong chemical bonding of metal ions with the functional groups, such as carbonyl groups and amide groups, in the polymer chain, which are suggested to be responsible for the crosslinking behavior. Moreover, silver ions loaded into the film are readily self-reduced and provides us a convenient route to disperse very small metal nanoparticles into the polymeric matrix. Meanwhile, strong accelerating effect of silver ions was observed on the hydrolysis of PAA molecules and the characterization results indicate that about 14-16 wt% precursors were dissolved during the ion exchange in the aqueous silver ion solutions. Fortunately, it is found that the metal-ion-induced crosslinking structure formed in the silver-doped film has helped to prevent the damaging effect of silver ions and the essential structural features of PAA were retained in the remaining polymer matrix.     

The synthesis and sodium-silver ion exchange of sodalites

Aluminosilicate sodalites of three different types--chlorosodalite, basic sodalite, and oxalate sodalite--have been synthesized in their sodium forms using hydrothermal synthesis. The syntheses were investigated in terms of their relative rates of crystallization and final crystallinities using powder X-ray diffraction. These sodalites were subsequently loaded with silver by aqueous ion exchange. The exchange was studied primarily by monitoring the solution phase. Rate of exchange and equilibrium behavior have been established over the temperature range of 25-80°C for all three types. Extreme selectivity toward silver over sodium was observed, with little dependence on temperature. Both sodium and silver sodalites were characterized by powder diffraction, and crystallographic data for silver sodalites have been derived using Rietveld refinement. Electron micrographs of sodalites have been used for investigations of crystallite morphology and size. Silver sodalites have been observed to manifest various optical properties including photochromic, barochromic, thermochromic, and fluorescent behavior.     

Silver ion high-performance liquid chromatography of the triacylglycerols ofCrepis alpina seed oil

The triacylglycerols ofCrepis alpina oil were characterized because this oil has a high concentration of crepenynic (cis-9-octadecen-12-ynoic) acid, a fatty acid useful in the chemical synthesis of deuterated fats for human metabolism studies. The triacylglycerols were separated from the crude oil by solid-phase extraction. Resolution, quantitation and isolation of the individual triacylglycerols were performed by silver ion high-performance liquid chromatography on a commercial column, an acetonitrile in hexane isocratic mobile phase and flame-ionization detection. Isolated triacylglycerols were identified by capillary gas chromatography of their fatty acid methyl esters. Of the eleven eluted triacylglycerols ofCrepis alpina oil, 85% included 35% tricrepenynoyl, 34% linoleoyldicrepenynoyl and 16% dilinoleoylcrepenynoyl glycerols. Triacylglycerols eluted according to the numbers of alkene and alkyne bonds. Elution times, resolution and quantitation were reproducible over a three-month period. The flame-ionization detector response required no response factors for quantitation of the triacylglycerols present inCrepis alpina oil. The silver ion chromatography system permitted the identification of 95% of the triacylglycerols compared to 70% of the triacylglycerols previously identified with reversed-phase high-performance liquid chromatography.     

Analysis of north atlantic and baltic fish oil triacylglycerols by high-performance liquid chromatography with a silver ion column

Triacylglycerols from Atlantic herring (Clupea harengus), sandeel (Ammodytes sp.) and Baltic herring (Clupea harengus membras) have been fractionated by silver ion high-performance liquid chromatography. An ion exchange column loaded with silver ions was the stationary phase, and a gradient in the mobile phase from 1,2-dichloroethane/dichloromethane (1∶1, v/v) to acetone and then to acetone/acetonitrile (2∶1, v/v) was used to effect the separation with light-scattering (i.e., mass) detection. Fractions were collected via a streamsplitter, and fatty acid methyl esters were prepared by transesterification in the presence of an internal standard for identification and quantification by gas liquid chromatography. Triacylglycerols were separated according to the number of double bonds in the fatty acyl residues. Resolution was excellent at first, when the least unsaturated molecules eluted (trisaturated to dimonoene-monodiene fractions). Base-line resolution could no longer be achieved when molecules containing trienoic or more highly-unsaturated fatty acids began to elute because of overlapping components. Nonetheless, some valuable separations of species containing two saturated and/or monoenoic fatty acids and one polyenoic fatty acid were achieved. Double bond indices (average number of double bonds in each triacylglycerol molecule) were calculated to estimate the separations possible. Fractions containing at least 11–14 double bonds per molecule were obtained.