Showing papers on "Argentometry published in 1990"
TL;DR: The inorganic ion exchanger chromium(III) hexacyanoferrate (III) has been found to be specifically selective for silver ions, with a sorption capacity of ca 10 mequiv g/1 of the exchanger as mentioned in this paper.
Abstract: The inorganic ion exchanger chromium(III) hexacyanoferrate(III) has been found to be specifically selective for silver ions, with a sorption capacity of ca 10 mequiv g–1 of the exchanger Sorption of the silver ions from acidic (10 mol dm–3 HNO3) and salt solutions (8 mol dm–3 NH4NO3), containing different levels of silver nitrate, has been studied The studies, which were aimed at using the exchanger for the recovery of silver ions from the waste, generated from chemical oxygen demand determinations, showed ca 80–95% recovery of silver ions from concentrated waste The exchanger also selectively removed silver ions from simulated waste containing Bi, Ca, Cd, Co, CuII, Mg, Mn, Ni, Pb and Zn ions
48 citations
01 Jun 1990-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the rotating disk technique was used to study silver dissolution with thiourea as a function of sulfuric acid, ferric sulfate, and thiaourea concentrations.
Abstract: The rotating disk technique was used to study silver dissolution with thiourea as a function of sulfuric acid, ferric sulfate, and thiourea concentrations. The effect of many foreign ions (Mn, Cu, Co, Ca, Na,etc.) and various additives was also examined. The dissolution of silver was zero order with sulfuric acid, first order with ferric sulfate, and second order with thiourea. Among the foreign ions, copper had a dramatically negative effect. The strong oxidants such as hydrogen peroxide and manganese dioxide were also detrimental for silver dissolution. According to the temperature effect studied (5 °C to 35 °C), the activation energy was 22.6 kJ/ mole. Silver does not dissolve with thiourea in the absence of ferric ions. Sulfuric acid does not participate in the dissolution reaction. The most important parameter for silver dissolution is the ferric sulfate/thiourea ratio. In excess ferric sulfate, a solid silver-thiourea complex is formed, which precludes transfer of silver into solution. In excess thiourea, the free thiourea reacts with formed solid silver-thiourea complex, and silver goes into the solution, predominantly as the dimers of AgTU+
3 complexes. The solid silver-thiourea complex in question was characterized by various spectroscopic, microscopic, and chemical analysis techniques. According to chemical composition, it corresponds to Ag2SO2·3TUH2O compound.
25 citations
TL;DR: In this paper, the effects of HOL and Bu-A concentrations, pH and temperature on flotation efficiency were examined, and nearly 99% of silver ions were floated under the optimum conditions.
Abstract: The flotation of silver ions from aqueous solutions using butylamine (Bu-A) and oleic acid (HOL) as a surfactant has been investigated. The effects of HOL and Bu-A concentrations, pH and temperature on flotation efficiency were examined. Nearly 99% of silver ions was floated under the optimum conditions. The addition of some cations to the flotation medium markedly affects the floatability of silver ions. This effect could be eliminated by adding EDTA. The technique was successfully extended to float silver ions from a synthetic mixture. In the determination of silver by atomic absorption spectrophotometry, Bu-A was used to eliminate the interference effects of some organic compounds by adding it to both the sample and the standard solutions. The mechanism of this elimination is discussed. Moreover, estimation of silver ions in synthetic mixtures was demonstrated.
6 citations
TL;DR: In this article, the authors proposed a method for measuring the effect of a small amount of fuel on the performance of a large amount of users. But the method was limited to 5 ml and the number of users was limited.
Abstract: クロム酸銀と塩化物イオンとの置換反応を利用する方法(クロム酸銀法)によって,フレッシュコンクリート中の塩化物の分析法を検討した.緩衝溶液として0.1M(1M=1 mol dm-3)ホウ酸ナトリウム-0.1 M硝酸溶液を用い,置換反応を行うと良好な結果が得られることが分かった. 100mlメスフラスコにフレッシュコンクリート濾液及び0.1M硝酸を各1 ml採り,これに緩衝溶液5 mlを加える.蒸留水を標線まで満たした後, 100～200メッシュのクロム酸銀200mgを加え, 2分間激しく振り混ぜる.過剰のクロム酸銀及び生成した塩化銀をNo.5Cの濾紙で濾別し濾液に4Mアンモニア水1 mlを加える.置換反応で生じたクロム酸イオンを厚さ1cmのセルを用いて波長405nmで吸光光度定量し,塩化物の濃度を求めた.検量線は塩化物イオン1～90mg dm-3の範囲で直線となり,この方法によって,フレッシュコンクリート中の3～170mMの塩化物イオンが相対標準偏差2～7%で定量できることが分かった.
5 citations
1 Jul 1990
TL;DR: In this article, the formation of silver chloride was studied in a rotating silver disc electrode by oxidation with [CoIII(NH3)5Cl]2+ in acid solution and subsequently reduced galvanostatically in order to determine quantitatively the amount of silver formed during the chemical oxidation.
Abstract: Silver chloride was formed on a rotating silver disc electrode by oxidation with [CoIII(NH3)5Cl]2+ in acid solution and subsequently reduced galvanostatically in order to determine quantitatively the amount of silver(I) formed during the chemical oxidation. By varying both the oxidation time and the concentration of the cobalt complex as well as that of chloride the kinetics of the formation of silver chloride was studied indirectly. As long as the concentration of chloride exceeds that of the cobalt(III) complex the reaction is first order in [CoIII(NH3)5Cl]2+ and almost zero order in Cl−. The diffusion controlled process can be explained with the theory of mixture potential and mixture current and may therefore be regarded as a corrosion process.
3 citations
Patent•
27 Aug 1990TL;DR: In this paper, a pyrometallurgical process is provided in which chloride residues are smelted with an agent such as sodium silicate that provides alkali metal oxide without generating gases, such as carbon dioxide, that would result in foaming during smelting to a material extent.
Abstract: This invention relates to the recovery of silver values from silver chloride or mixed chlorides including silver chloride. A pyrometallurgical process is provided in which chloride residues are smelted with an agent such as sodium silicate that provides alkali metal oxide without generating gases, such as carbon dioxide, that would result in foaming during smelting to a material extent.
2 citations
Patent•
11 Jan 1990
TL;DR: In this article, a reduction of silver halides with aldoses in the presence of an alkali metal hydroxide was proposed to recover good yield by reduction of the halides.
Abstract: Silver is recovered in good yield by reduction of silver halides with aldoses in the presence of an alkali metal hydroxide.
1 citations
TL;DR: In this paper, the potential changes of this electrode during the reaction of silver ions with iodide were theoretically explained and agree well with those measured, and it was tested for the argentimetric determination of iodide ion.