PDF Publication Title:
Text from PDF Page: 170
160 Ralf Steudel Fig. 1 Schematic model for the composition of the particles in hydrophilic sulfur sols consisting of long-chain polythionates Sn(SO3)2 and sulfur homocycles Sn The average density of the sol particles has been determined both before and after precipitation. For the dissolved particles a value of 1.92 g cm3 has been found at 16 C [30, 36] which is close to the density of liquid sulfur when extrapolated to 16 C [37]. A value of 1.9 g cm3 was obtained for sol particles precipitated by K+ or Ba2+ ions, while coagulation by Na+ ions yields particles with densities of between 1.2 and 1.4 g cm3 [36]. Evidently, the sodium salts of Raffo sol particles contain considerable amounts of H2O molecules and therefore can be peptized in water while the more or less water-free potassium and barium salts do not re-dissolve in water. The reversible coagulation of Raffo sols is strongly temperature depen- dent. The higher the temperature the more “soluble” the particles are. In other words, peptization is promoted by increasing temperatures, and since this dependence is exponential an increase in temperature T from 10 C to just 17 C may result in an increase in sulfur concentration c in the aqueous phase by a factor of 1000 (at a NaCl concentration of 0.101 mol l1) [14]. OdØn has shown that Raffo sols can be separated into fractions of differ- ing particle size by fractional precipitation with increasing concentrations of NaCl. As larger the particles as less NaCl is needed for precipitation [38]. Under special conditions monodispersed Raffo sols of particle size between 0.1 and 1.0 mm can be prepared directly from very dilute aqueous thiosulfate and sulfuric acid or hydrochloric acid without fractionation. These sols are characterized by higher order Tyndall spectra [39]. Several authors [12, 40] prepared Raffo sols free of cations other than H3O+ by removing the sodium ions by electrodialysis and studied the prop-PDF Image | Topics in Current Chemistry
PDF Search Title:
Topics in Current ChemistryOriginal File Name Searched:
Elemental-Sulfur-und-Sulfur-Rich-Compounds-I.pdfDIY PDF Search: Google It | Yahoo | Bing
Sulfur Deposition on Carbon Nanofibers using Supercritical CO2 Sulfur Deposition on Carbon Nanofibers using Supercritical CO2. Gamma sulfur also known as mother of pearl sulfur and nacreous sulfur... More Info
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)