ChemInform Abstract: The Electro‐Oxidation of Some Insoluble Inorganic Sulfides, Selenides, and Tellurides in Cationic Surfactant‐Aqueous Sodium Hydroxide Systems

Abstract

ChemInform Abstract is studied using two types of cells, a slurry cell and a sandwich cell. Voltammetric and coulometric measurements show that a cationic surfactant such as Hyamine 2389 is useful in performing electrolytic oxidations of insoluble, difficultly oxidizable sulfides, selenides, and tellurides. The controlled potential coulometric studies show that it is possible to perform oxidations to produce X0, XO32-, and XO42-(X: S, Se, Te) with a current efficiency of 100%. The half-wave potentials for the oxidation of the sulfides of Pb(II), Mn(II), Ni(II), and Mo(IV) are close to each other and the oxidation potentials of the selenides studied are identical to each other but different from the corresponding sulfides. The fact that the oxidations to form Se0 and Te0 all occur at the same potential and that this potential agrees reasonably well with the potential for the oxidation of the surfactant indicates that the oxidation mechanism involves electrooxidation of the surfactant and subsequent chemical oxidation of the chalcogenide.

Acrylonitrile-Induced Synthesis of Polyvinyl Alcohol-Stabilized Selenium Nanoparticles

“…9 Selenous acid and sodium selenite are the most frequently used selenium precursors in reduction methods, and the commonly used reducing agents are glutathione, hydrazine, dextrose, ascorbic acid, sodium ascorbate, and so forth. Also, there are a few reports on the formation of selenium nanoparticles by oxidation methods, such as reaction of hydroxyl radicals with selenourea, using a radiolysis technique, 13 electrochemical oxidation of selenide ions, 14 and so forth. We have recently reported acidinduced formation of selenium nanoparticles from sodium selenosulphate, 15 analogous to the well-known acid-induced formation of colloidal sulfur from sodium thiosulphate, and subsequently, it has also been reported by Stroyuk et al 16 In the present study, we report a new simple wet chemical method for the synthesis of polyvinyl alcohol (PVA)-stabilized selenium nanoparticles by reaction of sodium selenosulphate with acrylonitrile monomer, at ambient conditions.…”

The Electro‐oxidation of Some Insoluble Inorganic Sulfides, Selenides, and Tellurides in Cationic Surfactant‐Aqueous Sodium Hydroxide Systems

“…This paper is a report on an extension of the previous studies (9)(10)(11) to electro-oxidation of several other sulfides and some selenides and tellurides suspended in surfactant systems. The purpose of these studies was to investigate the possible use of these surfactant systems in electroanalysis of insoluble powders and in areas of massive electrolysis such as electrolytic roasting of minerals.…”

“…The previous studies (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) have shown that cationic surfactants affect these electro-oxidations in two ways. They solubilize the solids and form a hydrophobic film on the electrode, increasing the oxidation potential of water by 0.9V.…”

“…Recently, as part of a series of studies on the uses of cationic surfactants in the electro-oxidation of insoluble, difficulty oxidizable compounds (1)(2)(3)(4)(5)(6)(7)(8), it was reported that it was possible to electrolytically oxidize iron pyrite (9,10) and galena (11) powders in a cationic surfactant-aqueous sodium hydroxide system. Previously, electrolytic oxidation studies of these sulfide minerals to obtain answers to questions in the field of mineral processing have primarily utilized crystalline electrodes or powders mounted in graphite paste or epoxy cements (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26).…”

“…Anionic and neutral surfactants solubilize insoluble solid powders but do not appreciably increase the oxidation potential of water. In order to separate these two effects two types of cells (9,11) have been used: (i) a beaker cell for study of slurries of the powdered compounds (in this cell both the solubilization and filming effects were evident); (ii) a sandwich cell (in this cell the solid was trapped next to the electrode by a piece of filter paper and thus one observed only the filming effect).…”