Search results for "SOLUBILITY"

Electrochemical conversion of pressurized CO2 at simple silver-based cathodes in undivided cells: study of the effect of pressure and other operative…

2020

Abstract Electrochemical reduction of pressurized CO2 is proposed as an interesting approach to overcome the main hurdle of the CO2 electrochemical conversion in aqueous solution, its low solubility (ca. 0.033 M), and to achieve good faradaic efficiency in CO using simple sheet silver cathodes and undivided cells, thus lowering the overall costs of the process. The effect on the process of CO2 pressure (1–30 bar), current density, nature of the supporting electrolyte and other operative conditions, such as the surface of the cathode or the mixing rate, was studied to enhance the production of CO. It was shown that pressurized conditions allow to improve drastically the current efficiency o…

Solubilization control by redox-switching of polysoaps

2008

Reversible changes in the self-organization of polysoaps may be induced by controlling their charge numbers via covalently bound redox moieties. This is illustrated with two viologen polysoaps, which in response to an electrochemical stimulus, change their solubility and aggregation in water, leading from homogeneously dissolved and aggregated molecules to collapsed ones and vice verse. Using the electrochemical quartz crystal microbalance (EQCM), it could be shown that the reversibility of this process is better than 95% in 16 cycles.

Effects of the nature and concentration of substrates in aqueous solutions on the solubility of aroma compounds

2005

The solubility of nine aroma compounds (acetone, 2-butanone, 2-hexanone, 2-octanone, ethyl acetate, ethyl butanoate, ethyl hexanoate, n-hexanal, and n-hexanol) in both water and various aqueous solutions was measured at 25 °C using the mutual solubility method. The aqueous solutions consisted of sucrose, glucose, sorbitol, glycerol, polyethylene glycol 200, or maltodextrins at different concentrations. Aroma solubility in water decreased with increased hydrophobicity. For aroma molecules which have the same number of carbon atoms in their structure, aqueous solubility decreased as follows: aldehyde > methyl ketone > alcohol > ethyl ester. When using a group contribution method, the estimate…

Water-Soluble Polysaccharides from Ephedra alata Stems: Structural Characterization, Functional Properties, and Antioxidant Activity

2020

In this study, the physicochemical characterization, functional properties, and antioxidant activity of polysaccharides extracted from Ephedra alata (EAP) were investigated. EAP were extracted in water during 3 h with a liquid/solid ratio of 5 in a water bath at 90 &deg

1986

The kinetics of polyamidation was investigated for the reaction of diphenyl terephthalate as activated diester with trimethylhexamethylenediamine (1 : 1 mixture of 2,2,4- and 2,4,4-trimethyl isomers) in dimethyl sulfoxide. The good solubility of the resulting polyamide (Trogamid®(poly(iminoterephthaloylimino-x,y,z-trimethylhexamethylene))) assured a reaction in which all reactants, especially the polyamide, were soluble. The conversion was followed by analysis of the phenol set free and by measuring the number-average degree of polymerization Pn of the polyamide. The reaction obeyed an overall second order with the principle of equal reactivity of functional groups fulfilled for Pn ≿ 16. De…

Speciation and oxidation kinetics of arsenic in the thermal springs of Wiesbaden spa, Germany.

2001

Since 1886 arsenic has been known to be present as a trace component in the Wiesbaden thermal waters at concentrations of over 100 microg L(-1). In this study for the first time molecular level speciation of arsenic was measured both in the water (by HG-AAS) and in wellstone scale deposits (by XANES). Most of the arsenic in the anoxic NaCl-type waters is in the reduced arsenite form. Hydrous ferric oxide (HFO) precipitates in the scale deposits scavenge only the minor dissolved arsenate portion which is, however, accumulated up to 3% w/w. Isothermal precipitation experiments at in-situ temperatures showed a difference between the progress of both arsenic and iron oxidation and precipitation…

Deconvolution procedure of the UV-vis spectra. A powerful tool for the estimation of the binding of a model drug to specific solubilisation loci of b…

2015

UV-vis-spectra evolution of Nile Red loaded into Tween 20 micelles with pH and [Tween 20] have been analysed in a non-conventional manner by exploiting the deconvolution method. The number of buried sub-bands has been found to depend on both pH and bio-surfactant concentration, whose positions have been associated to Nile Red confined in aqueous solution and in the three micellar solubilisation sites. For the first time, by using an extended classical two-pseudo-phases-model, the robust treatment of the spectrophotometric data allows the estimation of Nile Red binding constant to the available loci. Hosting capability towards Nile Red is exalted by the pH enhancement. Comparison between bin…

Über die Autoxydation ungesättigter Verbindungen VIII. Mitteilung. Eine Methode zur erfassung des anfangsverlaufs der Autoxydation

1959

Es wird eine Methods beschrieben, die den Anfangsverlauf der Autoxydation von substanzen mit niedrigem Dampfdruck (Linolsauremethylester) manometrisch zu verfolgen gestattet. Die Reaktionsgefase sind mit einer Ampullenzertrummerungsvorrichtung ausgestattet, so das die Substanz erst zu einem genau festgelegten Zeitpunkt mit Sauerstoff in Beruhrung gebracht werden kann. Es ist so moglich, die Lolichkeit des Sauerstoffs in der Substanz zu bestimmen. A method is described which measures manometrically the beginning of the autoxidation of substances of low vapour pressure (methyllinoleate). The reaction vessela are fitted out with an equipment to break the ampoules, so that the substance can be …

Investigation of the He solubility in H2O-CO2 bearing silicate liquids at moderate pressure: a new experimental method

2000

We have designed the first available experimental method capable to investigate the solubility of inert gases in H2O–CO2 bearing silicate melts in a large range of pressures. The method overcomes the difficulties imposed by the physical state of volatiles at room conditions. Experiments were done by using an internally heated pressure vessel, where sealed capsules containing the sample are introduced. The peculiarity of the method consists in the capability of loading, in accurately known proportions (even lower than ppm), volatiles in a gaseous state at room conditions. Gas is loaded as a weighed amount of a gas-bearing glass, which was previously prepared by using the same gas as a pressu…

Aqueous phase/nanoparticles interface: hydroxypropyl cellulose adsorption and desorption triggered by temperature and inorganic salts

2012

The study highlighted the main forces driving the adsorption of hydroxypropyl cellulose (HPC) onto clay nanoparticles with a disk-like shape (Laponite RD). Modeling the isothermal titration calorimetry data provided the key thermodynamic properties, which enabled us to discuss the microscopic aspects contributing to the energetic and the entropic changes of the polymer adsorption at the nanoparticle/liquid interface. We evidenced that the process is strongly enthalpy-driven and that the interactions lead to constraints of the HPC configuration at interface. The functionalized nanoparticles enhanced the polymer solubility in water expanding the one-phase area of the binodal curve. Temperatur…