Authors:Yuri I. Aristov, Yulia A. Kovalevskaya, Michael M. Tokarev and Igor E. Paukov
experimental measurement of the heat capacity of a complex system which consists of two components of comparable weight fractions, namely, a silicagel KSK and calcium chloride confined to its pores [ 1 ]. The main motivation was to obtain for this composite
Benzoylthiourea derivatives (N,N-diphenyl-N′-(3-methylbenzoyl)thiourea and diphenyl-N′-(4-methylbenzoyl)thiourea) were impregnated onto silica gel. The preconcentration of uranium(VI) from aqueous solution was
investigated. Extraction conditions were optimized in batch method prior to determination by uv–visible absorption spectrometry
using arsenazo(III). The optimum pH for quantitative adsorption was found as 3–7. Quantitative recovery of uranium (VI) was
achieved by stripping with 0.1 mol L−1 HCl. Equilibration time was determined as 30 min for 99% sorption of U(VI). Under optimal conditions, dynamic linear range
of for U(VI) was found as 0.25–10 μg mL−1. The relative standard deviation as percentage and detection limit were 5.0% (n = 10) for 10 μg mL−1 U(VI) solution and 8.7 ng mL−1, respectively. The method was employed to the preconcentration of U(VI) ions in soil and tap water samples.
Authors:Hasan Demir, Moghtada Mobedi and Semra Ülkü
and adsorptive, shape and size of pores, etc. Aristov et al. [ 8 ] obtained sorption behavior of water vapor on Fuji RD silicagels which have 820 m 2 g −1 BET surface areas and particle size between 0.3 and 1.0 mm using CAHN 2000 thermo
The chromatographic behavior of uroporphyrin I, uroporphyrin III, coproporphyrin I, coproporphyrin III, and protoporphyrin IX has been examined using silica gel 60F
, polyamide 11F
, and cellulose F TLC plates as stationary phases. Homologous series of
-alcohols, acetonitrile, and tetrahydrofuran were used as mobile phases. Chromatographic retention data and a possible retention mechanism are discussed. The electrostatic interactions operating in these chromatographic systems were analyzed by studying relationship between log (1/
) values and the molecular polarizabilities of the solvents.
Authors:Łukasz Komsta, Patrycja Smardz, Rafał Pietraś, Robert Skibiński and Anna Gumieniczek
The retention (RM) values of nine one-point adsorption model compounds: diphenylamine, indol, 2-naphtol, 1-naphtol, 1-naphtylamine, 4-toluidine, carbazole, 4-chloraniline, and thymol were investigated on silica gel using six modifiers: acetone, dioxane, hexane, isopropanol, methylethylketone, ethyl acetate, and tetrahydrofurane (in hexane). These compounds showed small but visible curvilinearity of dependence of RMvs. modifier concentration. This curvilinearity is very similar among the investigated compounds, so relative differences of extrapolated RM are almost the same (strictly intercorrelated) regardless of the regression technique used. We have compared several robust and weighted regression methods and investigated their impact on extrapolated values. It can be concluded that one should primarily consider weighted regression with 1/x weights during retention extrapolation. It seems to be a better alternative than classical regression (better extrapolation) and also better than polynomial approaches (better stability).
Authors:E. Illeková, M. Miklošovičová, O. Šauša and D. Berek
quality of diesel fuel and other fuel mixtures [ 1 ].
Silicagel is a solid formed by silicon dioxide, SiO 2 . It may contain admixtures of different inorganic and organic substances. Due to the presence of Si–OH groups (silanols), surface of non
Authors:D. K. Sawant, H. M. Patil, D. S. Bhavsar, J. H. Patil and K. D. Girase
silicagel so that a very slow reaction occurs with the formation of a sparingly soluble compound. When the concentration of this compound exceeds the solubility limits, crystals will be formed, while the main function of the gel is to control the flow of
The use of ionizing radiation to achieve some desired effect on silica gel, applicable to the adsorption of radionuclides
has been investigated as a function of the dose-rate over a wide range of doses, in experiments with strongly alkaline aqueous
solutions containing an excess of UO
relative to trace concentrations of88Y,103Ru,134Cs and141Ce. The results obtained revealed that γ-irradiation of silica gel was reproduced with an uptake comparable to that measured
for the unirradiated-silica gel. Radiation resistance is strongly influenced by the basic macromolecular structure, the presence
of water, and the particular environmental exposure conditions.
Thermogravimetric analysis of silica gel has shown that the loss in weight between 30° and 910°C can be quantitatively explained
on the basis of water being lost from three distinct and different populations of sites on the silica gel surface. The results
indicate that the site energies of the three different populations are randomly distributed and, consequently, the resulting
weight loss steps from each population can be described by the integral of a simple normal distribution with temperature.
The calculated weight loss obtained by assuming three different site-groups having randomly distributed adsorption energies
is, within experimental error, coincident with the experimental data. It is also shown that the water evolved from the second
population of sites originates from strongly bound water and may also contain water generated by the condensation of (geminal)
silanol groups contained in the overlapping and neighbouring population.
Microcrystalline zirconium phosphate (-ZrP), hydrous manganese dioxide (HMnO), ammonium molybdophosphate (AMP) and silica gel supported forms of these materials as well as silica gel (SG) itself were investigated by thermoanalytical, electron microscopic, X-ray diffraction and infrared spectrometric methods. Chemical composition, structure and some related properties of the inorganic ion exchangers mentioned above are reported.