A simple static method based on gravimetric measurements has been adopted to measure the solubility of benzenecarboxylic acid, 2-hydroxy-benzenecarboxylic acid, 4-hydroxy-benzenecarboxylic acid and ...1,8-dihydroxyanthraquinone along several isotherms in the temperature range 318–357 K and the pressure interval 7–23 MPa. Solubility data have been correlated with the Zieger–Eckert approach, using the Fedor atomic and group contribution method to estimate the solubility parameter and the molar volume of the solutes. A good agreement was obtained between data reported in the literature and those determined using the proposed method which allows one to measure solubility mole fraction as low as 10
−5. Provided that a suitable analytical technique is adopted the method can be extended also to multicomponent systems.
The interactions of iodine with each of the electron donors 1-aza-15-crown-5 (AC) and 3,6,9,14-tetrathiabicyclo9.2.1tetradeca-11,13-diene (TTBCTD) in CHCl
3 have been described in terms of 1:1 and ...1:2, base: I
2 complexes, respectively, forming the complexes of the type (AC)
2I
+·I
3
− and (TTBCTD)(I
2)
2. The (AC)
2I
+·I
3
− shows the characteristic absorptions of I
3
− ion at 265 and 365
nm while the charge-transfer transition of (TTBCTD)(I
2)
2 occurs at 320
nm. The formation of the two complexes was further confirmed by far infrared measurements. The values of the complex formation constant,
K, and the absorpativity,
ε in CHCl
3 are calculated for the complex (AC)
2I
+·I
3
−.
This study provides an experimental investigation on the corrosion behaviour of three carbon steels used for pipeline application. The susceptibility of these materials to corrosion damage was ...analysed in order to simulate its service conditions particularly under disbonded coating. Monitoring of open‐circuit potential (Efree), polarization resistance (Rp) and measuring of the weight loss during immersion time were used to evaluate the corrosion behaviour of the studied materials. All the corrosion experiments were performed in two aqueous solutions: natural seawater and synthetic one (3 wt% NaCl solution). The morphology of the corrosion products was examined by optical microscopy. The results obtained from electrochemical tests have shown different behaviour for the studied steels into the retained corrosive environments: more stable potentials (Efree), higher Rp‐values with large fluctuations evolution were found in natural seawater. The gravimetric measurements have also shown a continuous variation of the weight loss throughout the exposure period in the sodium chloride solution. However, it seemed that a passive behaviour was observed in natural seawater. A little difference was observed between all the studied steels in terms of corrosion kinetics. The steel, having the little ferritic grain size, seems to be more resistant to corrosion damage. Qualitatively, a porous and non‐adherent oxide film was observed on the corroded surface in the synthetic solution; while, the rust layer, which is formed in the natural seawater, has acted as a barrier of corrosion process. Finally, all the results obtained from both electrochemical tests and weight loss measurements were in reasonably good accordance. The important common point that can be concluded was that all the tested materials seem to be more suitable for natural seawater than 3 wt% NaCl solution. Also, they are not recommendable to be used in an environment where chloride attack is possible and important.
A new version of the Russian absolute field gravimeter GABL-M with a green Nd:YAG laser developed at the Institute of Automation and Electrometry of the Siberian Branch of the Russian Academy of ...Sciences is discussed. The gravimeter is described briefly and its technical characteristics are given, along with some results from the first measurements under various conditions. (Field measurements were made in a tundra region.)
Acta Scientiarum Polonorum. Geodesia et Descriptio Terrarum 7
Streszcz., słowa kluczowe oraz podpisy pod ryc. i tab. również w jęz. ang.
Acta Scientiarum Polonorum. Geodesia et Descriptio Terrarum 7
...Streszcz.Keywords and signatures in Figure and tab. Also in a moan. English
Mass transfer in single porous particles is studied by measuring uptake rates in porous single particles and by modelling these rates with a non-isothermal, non-isobaric Maxwell–Stefan model. Uptake ...curves of carbon dioxide, methane and ethane in specially prepared activated carbon extrudates were measured in a gravimetric analyser in a broad range of temperatures, concentrations and pressures. The model describes mass transfer due to pore diffusion (bulk and Knudsen diffusion), viscous flow and surface diffusion. To identify the different types of mass transport in the porous particles two types of kinetic uptake measurements were performed: responses to pure component pressure steps and responses to concentration steps at constant feed pressure. All transport mechanisms contribute significantly to the total molar flux. Surface diffusion is an important transport mechanism at low temperatures and at small step changes in both concentration and pressure. Viscous flow is not only important in experiments with a total pressure change but also in concentration step experiments at constant total pressure.
This paper reports transient weight curves of La
0.2Sr
0.8CoO
3−
δ
(LSC) membrane (crashed in small grains) subject to an instantaneous change of oxygen activity in the gas phase. When the ...surrounding gas changes between pure oxygen and helium, the LSC sample experiences a slow weight loss in the oxygen desorption period and a rapid weight gain in the oxygen absorption period due mainly to the difference in the driving force. The LSC sample undergoes phase transformation/chemical reaction with the surrounding gas changing between the pure oxygen and methane. A mathematical model considering surface reaction as the rate-limiting step is presented to describe the oxygen transport through the membrane material, and employed to obtain the surface reaction rate constants. A simple correlation between the oxygen permeation flux and rate constants measured by the transient thermogravimetric analysis (TGA) method is given. The oxygen permeation fluxes calculated from the data measured by the present TGA method are consistent with the data measured by the permeation method. The TGA method is found particularly useful for studying the surface reaction rates of oxygen permeation through thin mixed-conducting ceramic membranes.
Acta Scientiarum Polonorum. Geodesia et Descriptio Terrarum 7
Streszcz., słowa kluczowe oraz podpisy pod ryc. i tab. również w jęz. ang.
Acta Scientiarum Polonorum. Geodesia et Descriptio Terrarum 7
...Streszcz.Keywords and signatures in Figure and tab. Also in a moan. English
PDF