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.
Authors:X. Wang, W. Zimmermann, K. Ng, A. Chakraboty, and J. Keller
This article presents results of the experimental investigation on the adsorption of the water vapor on silica gel. Two independent
experimental methods has been used, viz. the constant-volume-variable-pressure (CVVP) system and variable pressure thermogravimetry
(TG). Results from these two methods are compared with each other. Also the isosteric heat of adsorption of this system has
been determined from the equilibrium data. The silica gels investigated here are Fuji Davison type 'A' and type 'RD'. Adsorption
isotherm of water vapor have been measured under a variety of conditions all referring to chiller operation cycles, i.e. temperatures
from 303 to 358 K and pressures from 500 to 7000 Pa. The data collected from the two independent experiments compare very
favorably with each other and their trends are consistent with those of the adsorption chiller manufacturer. This lends significant
weight to our experimental data on silica gel+water systems as being valuable to the adsorption chiller manufacturers and
the scientific community.
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 Q-TG mass loss and first derivative Q-DTG mass loss accompanying benzene thermodesorption from silica gel samples under
quasi-isothermal conditions were studied with a Derivatograph Q-1500 D (MOM, Hungary). The isotherms of adsorption-desorption
of benzene vapour on different porous silica gels were measured gravimetrically by using a McBain balance. The benzene mass
loss in the adsorption region, obtained from the Q-TG curves, and the adsorption capacity, established gravimetrically, exhibited
a satisfactory correlation.
Authors:I. Sowa, D. Zajdel, R. Kocjan, M. Pizoń, and M. Wójciak-Kosior
The new obtained sorbent based on silica gel modified with polyaniline was used as a stationary phase in the ion chromatography of anions. NO3- and NO2- ions were analyzed by UV spectrophotometric detection (200 nm). It can be stated that the optimal mobile phase was a 0.05 M hydrochloric acid and the optimal flow speed was 0.3 mL min−1. The separation of both anions in the presented condition was satisfactory. The resolution factor (peak resolution) was 3.3. It suggests the possibility of the column application for simultaneous speciation analysis of nitrate ions.
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: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
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.
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.