Über pH-Werte nichtwässeriger Lösungen
TL;DR: In this paper, the acidity function of Hammett's acidity functions H0 and H− have been determined with an indicator of aniline type and a phenol type respectively.
Abstract: In three series of solutions: HCl, an acetate buffer and a triethanolamine buffer, the solvent water has been replaced successively by ethanol. Hammett's acidity functions H0 and H− have been determined with an indicator of aniline type and an indicator of phenol type respectively. The indicators show a strong individual behaviour and the acidity function is by no means simply dependent on the charge type of the indicator used. The product of the proton activity and the activity coefficient of the chloride ion also has been determined in these solutions as well as the pH value, measured in a conventional manner using a cell with a liquid junction.
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TL;DR: In this article, the basicity of several basic ionic liquids is studied quantitatively for the first time, and they can be switched repeatedly by bubbling CO2 and N2 through the solution alternately.
87 citations
TL;DR: In a review article published more than 30 years ago, the present author stated " … several scales, all masquerading under the name pH, are in common use".
Abstract: 1. INTRODUCTION A. Background "Plus ca change, plus c'est la meme chose." In a review article published more than 30 years ago, the present author stated " … several scales, all masquerading under the name pH, are in common use. Many investigators are thinking and computing in terms of one definition and measuring a different quantity."1 An improvement toward an understanding of the nature of the practical pH value has been seen in the last three decades, but the precise manner of interpreting these values is still largely a mystery. To emphasize this situation, one has only to survey a dozen modern texts used in the teaching of analytical chemistry. The results of such an examination are summarized in Table 1. As observed earlier … "this state of confusion results in part from the impossibility of determining exactly … the molality and the activity of hydrogen (hydronium) ion for a buffer solution of moderate concentration."1
72 citations
TL;DR: In this paper, the effect of pH and of catalysts on the course of the hydrolysis and condensation of tetraethoxysilane (TEOS) in water-ethanol solution was studied with the aid of chromatography, potentiometry and gelation tests.
61 citations
47 citations
TL;DR: In this article, the dissolution kinetics of lignin and hemicelluloses as well as the depolymerisation kinetics during the fractionation process are expressed in terms of the H-factor, a parameter combining fractionation temperature and duration.
Abstract: The study describes SO2–ethanol–water fractionation of spruce as a promising basis for future Biorefineries. The dissolution kinetics of lignin and hemicelluloses as well as the depolymerisation kinetics of cellulose during the fractionation process are expressed in terms of the H-factor, a parameter combining fractionation temperature and duration. The raw material moisture content is shown to have a very small effect on the fractionation kinetics. The liquor-to-wood ratio has little effect on the process during the (delignification) bulk phase, while in the residual phase the effect becomes pronounced. During the latter phase, lower liquor-to-wood ratios lead to higher residual lignin content, lower residual hemicelluloses and pulp viscosity, but higher hemicelluloses removal selectivity. Higher delignification rates and selectivities are obtained at ethanol-to-water ratios close to 1 : 1 (w/w) and high SO2 concentrations (≥12 w/w%). Based on the presented data, the optimum fractionation conditions for the production of paper and viscose-grade dissolving pulps are quantified.
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