Lead-tin mirror formation from mixtures of red lead and tin sulphide

Mosaic gold, tin (IV) sulphide, is a yellow pigment which was known in antiquity but whose use was superseded by other more easily obtainable yellow pigments by the Renaissance. The identification of mosaic gold residues in a burnished golden mirror decoration on a XIIIth Century Spanish polychrome statue is important in that the first reference to the use of mosaic gold in the European literature dates from the XIVth Century, although the use of this material in China had been recorded some time before. In this paper, Raman spectroscopy, XRD and SEM are used in the analysis of the conditions required for the formation of golden mirrors using tin (IV) sulphide in admixture with dilead (II) lead (IV) tetroxide and mercury (II) sulphide. From these results, it is proposed that the major reactions are the reduction of Sn(IV) to Sn(0) with the accompanying oxidation of lead (II) oxide to lead (IV) oxide and the formation of lead (0) and lead (II) sulphide. From these results it was possible to explain the process of creation of the golden mirror from mosaic gold in the XIIIth Century.     

Seperations involving sulphides : Separation of alkaline earth metals from some elements that form sulphides

It has been shown that 2N sodium sulphide reagent can be used efficiently for separating. 1.Barium from rhenium, platinum, gold, bismuth, palladium, lead or cadmium. 2.Strontium, calcium and magnesium from rhenium, platium, gold, mercury, bismuth, palladium, lead or cadmium     

Separations involving sulphides : Separation of platinum,gold, selenium,arsenic, rhenium and molybdenum from lead

It has been shown that it is possible to determine platinum, gold, selenium, arsenic, rhenium or molybdenum in the presence of lead with 2N sodium sulphide reagent but not tellurium, antimony and tin.     

A study of the effect of some pollutant gases on cathodes used in membrane-covered amperometric oxygen detectors

The effects of various gaseous pollutants on the electrochemical activity of materials used as cathodes for membrane-covered amperometric oxygen detectors are described. It is shown that gold and platinum cathodes are not unduly affected by concentrations of sulphur dioxide and chlorine many times greater than those likely to be encountered in test solutions, and that a gold cathode is also unaffected by hydrogen sulphide. A platinum cathode is rapidly and significantly poisoned on contact with hydrogen sulphide; an analysis of the fall in the rate of oxygen reduction as a function of time indicates that the poisoning occurs by the blocking of surface sites by sulphide. The effect of hydrogen sulphide on silver, nickel and nickel sulphide electrodes is also reported. Of these materials, only nickel sulphide is an effective electrocatalyst for oxygen reduction in the presence of sulphide.     

纳米半导体硫化银单层膜的自组装

本文使用Triton X-100作为模板剂制备半导体硫化银纳米颗粒,并研究了其吸收光谱的兰移特性。在金属铝或金基底上自组装有机双功能分子单层膜后,将其浸入所制备的纳米硫化银颗粒的微乳液中,自组装得到硫化银纳米颗粒单层膜并研究了其表面形貌特征。     

Determination of gold in copper-bearing sulphide ores and metallurgical flotation products by atomic-absorption spectrometry

A method is described which is specific for the determination of gold in sulphide copper ores and concentrates. Direct decomposition with aqua regia was found to be incomplete. A carefully controlled roasting stage followed by treatment with hydrochloric acid and then aqua regia was effective for dissolving all the gold. The gold is extracted into 4-methylpentan-2-one (methyli-sobutylketone) then aspirated into a very lean air—acetylene flame and the gold determined by atomic-absorption spectrometry. No interferences were observed from large concentrations of copper, iron or nickel.     

Liquid-liquid extraction of palladium and gold by the sulphide podand 1,12-di-2-thienyl-2,5,8,11-tetrathiadodecane

The extraction properties of the sulphide podand 1,12-di-2-thienyl-2,5,8,11-tetrathiadodecane (TTD), an open-chain neutral polythioether with six sulphur donor atoms in 1,2-dichloroethane, chloroform and MIBK for Pd and Au in hydrochloric, nitric and perchloric acid media have been examined. The kinetic aspects of the extraction of palladium(II) from hydrochloric acid by TTD and dioctyl sulphide (DOS) were compared. The rate of Pd extraction with TTD is considerably higher than that with DOS, especially with chloroform. Combined use of a reducing agent and TTD enhances the extraction of gold(III) into 1,2-dichloroethane.     

Separations involving sulphides : Separation of bismuth,cadmium and indium from various other elements that form thiosalts

It has been shown that 2N sodium sulphide reagent can be successfully used in separating tellurium, molybdenum, antimony or rhenium from bismuth., platinum, gold, selenium, rhenium, arsenic, molybdenum or tellurium from cadmium; platinum, gold, selenium, rhenium, arsenic, molybdenum, tellurium or antimony from indium.It is not possible to separate quantitatively arsenic, platinum, gold or selenium from bismuth; antimony from cadmium; and tin from bismuth, cadmium or indium.     

Laser spectroscopy for atmospheric chemistry: selected applications involving the fluorescence technique

The application of laser-based techniques to the study of different problems related to atmospheric chemistry is well established. Among the various laser spectroscopic methods, the focus here is directed towards selected applications of the laser photofragmentation and fluorescence techniques, which are used to investigate the complex chemistry of tropospheric sulphur species, with particular emphasis on the oxidation of dimethyl sulphide (DMS) and the consequent formation of sulphuric acid, and to the possibility of detecting with very high sensitivity and selectivity a particular element (e.g., gold) in size-segregated aerosol particles in view of its possible release as a tracer in the atmosphere. The atomic fluorescence technique is also applied to the real time detection of lead in a miniature air-acetylene flame, in which monodisperse aerosol particle are introduced.     

Bis(4-methylpiperidine-1-carbodithioato)-lead(II) and Bis(4-benzylpiperidine-1-carbodithioato)-lead(II) as Precursors for Lead Sulphide Nano Photocatalysts for the Degradation of Rhodamine B

Bis(4-methylpiperidine-1-carbodithioato)-lead(II) and bis(4-benzylpiperidine-1-carbodithioato)-lead(II) were prepared and their molecular structures elucidated using single crystal X-ray crystallography and spectroscopic techniques. The compounds were used as precursors for the preparation of lead sulphide nano photocatalysts for the degradation of rhodamine B. The single crystal structures of the lead(II) dithiocarbamate complexes show mononuclear lead(II) compounds in which each lead(II) ion coordinates two dithiocarbamato anions in a distorted tetrahedral geometry. The compounds were thermolyzed at 180 ℃ in hexadecylamine (HDA), octadecylamine (ODA), and trioctylphosphine oxide (TOPO) to prepare HDA, ODA, and TOPO capped lead sulphide (PbS) nanoparticles. Powder X-ray diffraction (pXRD) patterns of the lead sulphide nanoparticles were indexed to the rock cubic salt crystalline phase of lead sulphide. The lead sulphide nanoparticles were used as photocatalysts for the degradation of rhodamine B with ODA-PbS1 achieving photodegradation efficiency of 45.28% after 360 min. The photostability and reusability studies of the as-prepared PbS nanoparticles were studied in four consecutive cycles, showing that the percentage degradation efficiency decreased slightly by about 0.51–1.93%. The results show that the as-prepared PbS nanoparticles are relatively photostable with a slight loss of photodegradation activities as the reusability cycles progress.     

Laser spectroscopy for atmospheric chemistry: selected applications involving the fluorescence technique

The application of laser-based techniques to the study of different problems related to atmospheric chemistry is well established. Among the various laser spectroscopic methods, the focus here is directed towards selected applications of the laser photofragmentation and fluorescence techniques, which are used to investigate the complex chemistry of tropospheric sulphur species, with particular emphasis on the oxidation of dimethyl sulphide (DMS) and the consequent formation of sulphuric acid, and to the possibility of detecting with very high sensitivity and selectivity a particular element (e.g., gold) in size-segregated aerosol particles in view of its possible release as a tracer in the atmosphere. The atomic fluorescence technique is also applied to the real time detection of lead in a miniature air-acetylene flame, in which monodisperse aerosol particle are introduced.     

Separations involving sulphides : Separation of thorium or titanium from some elements that form thiosalts

Sodium sulphide can be used to separate arsenic, antimony, tellurium, selenium, molybdenum, mercury, gold, platinum or rhenium from thorium and antimony, tellurium, selenium or mercury from titanium     

An investigation of the sulphur(−II)/sulphur(0) system on bold electrodes

Sulphur deposited on gold by the anodic oxidation of sulphur(−II) species in solution has been studied by X-ray photoelectron spectroscopy. The initial layer behaved as gold sulphide. Multilayers of sulphur had a lower volatility and a smaller electron binding energy than bulk elemental sulphur, indicating that there is interaction with the underlying gold or gold sulphide.The anodic oxidation of sulphur(−II) to sulphur, and the reverse process, has been investigated on gold using the rotating ring disc electrode technique. Polysulphide ions were formed as intermediates in both processes. Polysulphides were also produced by chemical reaction of deposited sulphur with sulphur(−II) species in solution. The polysulphide intermediates were identified as S²⁻₅ at pH 13, a mixture of species with average stoichiometry S²⁻_3.3 at pH 9.2 and S²⁻₂, possibly HS⁻₂, at pH 6.8.     

The reaction of trimethyllaluminum with lead sulfide

The reaction of trimethylaluminium with lead sulphide gives tetramethyl-lead, lead and bis(dimethylaluminium) sulphide. Under the experimental conditions the maximum degree of conversion of the methyl groups was 22.5% (0.5 h, 135°). The products were analysed by NMR spectroscopy.     

The surface morphology of ion-selective membrane electrodes: Part 3. Studies on the Lead Ion-selective Membrane

Studies of the changes in the surface state of the ion-selective membrane and in the performance of the silver sulphide-lead sulphide (2:1) precipitate-based electrode are described. A scanning electron microscope was used to examine the surface of the electrode membrane. The results indicate that passivation of the lead-selective electrode caused by chemical and electrochemical oxidation is due to transformation of the lead sulphide at the membrane surface. The electrode surface becomes depleted in lead sulphide; lead sulphate crystals are formed during chemical oxidation with hydrogen peroxide, and lead oxide crystals during anodic oxidation.     

Investigations of reactions involved in flameless atomic absorption procedures: Part VI. A Study of some factors influencing the determination of lead in sulphate matrices

The degree of interference from various sulphates in the determination of lead by flameless a.a.s. is high (e.g. the decrease in the signal from lead is 10% for 2 nanomol of sodium sulphate) and decreases in the order sodium ? potassium ? calcium ? magnesium. The interference from magnesium sulphate can be eliminated by ashing the sample at 870 ± 10°C. Results obtained from high-temperature equilibrium calculations show that gaseous lead sulphide is responsible for the interferences in the presence of sodium sulphate. Theoretical conditions for the formation of gaseous lead sulphide are outlined. The influence of carbon on the reactions involved was investigated by use of standard graphite as well as glassy carbon tubes; the results are compared with those found theoretically. In the presence of a tenfold excess of lanthanum(III), the recovery of lead is higher than 90% for all the sulphates investigated, at least up to an amount of 0.2 μ mol. The addition of oxygen as well as hydrogen to the inert gas decreases the interference from sodium sulphate, in accordance with the theoretical predictions.     

The application of thiosalts in analysis: A new scheme of qualitative analysis - Part C

1. Seveial modifications for improving the efficiency of the new scheme of qualitative analysis have been proposed. 2. It has been shown that 1N sodium sulphide is a more efficient and convenient reagent and may be substituted for concentrated ammonium sulphide. 3. If sodium carbonate is added along with sodium, sulphide, barium, strontium and calcium are precipitated completely with the sulphides and hydroxides and the division of these metals into two groups is prevented. 4. It has been shown that the tedious separation of cerium and thorium from the iron group by means of oxalic acid is unnecessary and these metals can be tested for conveniently with the metals of the iron group. 5. The division of thallium into the iron and copper groups can be avoided and the metal precipitated completely with the copper group by adding potassium iodide in the treatment with 1N hydrochloric acid. 6. Modified procedures liave been provided tor the detection of nickel, tellurium and gold.     

Studies with the Selectrode: Determination of Oxalate Ion Activity

Abstract

A solid state oxalate sensor is reported utilizing a commercial ion-selective electrode, the Selectrode^TM. Comparative measurements in aqueous solution of similar carboxylate ions and common inorganic anions, indicates appreciabl'e selectivity for oxalate. The Selectrode^TM was activated with a mixture of silver sulphide, lead sulphide, and lead oxalate.     

Separations involving sulphides: Separation of zinc from some elements that form thiosalts

It has been shown that 2 N sodium sulphide reagent can be used for separating arsenic, antimony, tellurium, selenium, molybdenum, mercury, gold, platinum or rhenium from zinc.     

New macroporous polymers for the selective adsorption of gold (III) and palladium (II). I. The synthesis,characterization, and effect of spacers on metal adsorption

New macroporous polymers with a functional group based on triisobutylphosphine sulphide are synthesized and characterized for the selective adsorption of gold and palladium. Five coordinating polymers are prepared from chloromethylated divinylbenzene polystyrene, by either direct attachement of the phosphine sulphide to the polymer or through a spacer chain that is modified to introduce O and S heteroatoms. The influence of the length and composition of the spacer chain on resin capacities is studied. The presence of O and S heteroatoms in the spacer increases the hydrophilicity of the polymers, and it is found to be essential for the adsorption of Au(III) and Pd(II). This is attributed to the coordination of the metal with the heteroatoms of the spacer. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 269–278, 2000