Authors:J. Poulis, E. Robens, C. Massen, and P. Staszczuk
Jntti published in 1970 a method to
obtain values of the sorption parameters at an early stage of gravimetric
sorption measurements. In the present paper we apply that method to volumetric
sorption measurements to discuss its applicability. A method is presented
to cope with inaccuracies when using Jntti’s method. This will
be of special importance for volumetric measurements where accuracy plays
a major part. In the paper a second order regression method is used. We use
a computer simulation as well as experimental data on desorption of nitrogen
from a silica aerogel at 77 K.
Authors:P. Staszczuk, D. Sternik, G. Chądzyński, E. Robens, and M. Błachnio
adsorption measured at 77 K was used to characterize the surface heterogeneity
of high-temperature superconductor surfaces. Properties relating to adsorption
and porosity of the solids (adsorption capacity, specific surface area, radii
and volume of the pores, pore-size distribution function) were determined
from nitrogen adsorption–desorption isotherms and atomic force microscopy
(AFM) for a series of oxide superconductors. It is shown that the adsorption
isotherms of all samples are S-shaped and belong to type II according to the
IUPAC classification. On the basis of the nitrogen adsorption isotherms and
AFM data, fractal dimensions were determined and correlations found with adsorption
and porosity parameters.
Authors:D. Sternik, P. Staszczuk, G. Grodzicka, J. Pękalska, and K. Skrzypiec
The paper presents the method of preparation and determination of physicochemical properties of silica gels with a chemically
bonded BSA phase as well as studies of the effect of support porosity on the synthesis. Wide-porous Z-300 and narrow-porous
Z-100 silica gels were studied. The investigations showed a significant effect of pore size on the synthesis of stationary
phases with BSA. Modification with protein results in changes of adsorption properties and porosity of adsorbent samples.
Changes of physicochemical properties result in significant changes of geometrical and structural heterogeneity of the support
(specific surface area, fractal coefficient) as well as energetic heterogeneity of the samples.
Authors:D. Sternik, M. Błachnio, P. Staszczuk, G. Chądzyński, and E. Kowalska
properties (adsorption capacity, desorption energy distribution and pore-size
distribution functions) of nanomaterial surfaces from selected materials,
based on sorptometric and liquid thermodesorption measurements under quasi-equilibrium
conditions, are presented. The fractal dimensions of nanotubes using sorptometric
and AFM data have been evaluated.
Comparison of thermogravimetric
and other data provide new information about the adsorption and pore structure
of the studied materials. The fractal dimensions of nanomaterial surfaces
using sorptometry are in good agreement with those from AFM.
Authors:P. Staszczuk, J. Bazan, M. Błachnio, D. Sternik, and N. Garcia
This paper presents possible applications of thermal analysis, sorptometry
and porosimetry to study physico-chemical properties of Na- and La-montmorillonite
samples, especially for determination of total surface heterogeneity. The
quasi-isothermal thermogravimetric (Q-TG) mass loss and its first derivative
(Q-DTG) curves with respect to temperature and time obtained during programmed
liquid thermodesorption under quasi-isothermal conditions have been used to
study adsorbed layers and heterogeneous properties of the Na- and La-montmorillonites.
Calculations of the desorption energy distribution functions by analytical
procedure using mass loss Q-TG and differential mass loss Q-DTG curves of
thermodesorption under quasi-isothermal conditions of polar and non-polar
liquid vapours preadsorbed on a material surface are presented. Parameters
relating to porosity of samples were determined by sorptometry, mercury porosimetry
and atomic force microscopy (AFM). From nitrogen sorption isotherms from sorptometry
and porosimetry methods, the fractal dimensions of montmorillonites have been
calculated. Moreover, a new approach is proposed to calculate fractal dimensions
of materials obtained from Q-TG curve; this is compared with values obtained
by the above methods. The total heterogeneous properties (energy distribution
function and pore-size distribution functions) of samples studied were estimated.
The radius and pore volume of the tested samples calculated on the basis of
thermogravimetry, sorptometry and porosimetry techniques were compared and
good correlations obtained.
Authors:G. Chądzyński, P. Staszczuk, D. Sternik, and M. Błachnio
Properties relating to porosity of solids (fractal dimensions, surface roughness parameters) were evaluated from atomic force
microscopy (AFM) and nitrogen adsorption-desorption isotherms measured at 77 K for selected high-temperature [(RE) Ba2Cu3O7−x, RE=Y, Sm] superconductors. Adsorption capacity, specific surface area, fractal dimensions were determined from adsorption-desorption
isotherms. The adsorption isotherms of all samples were S-shaped and belong to type II according to the IUPAC classification.
A linear relationship was demonstrated between the fractal coefficients calculated by using the two methods and values of
adsorption capacity of monolayer.
Authors:M. Błachnio, P. Staszczuk, G. Grodzicka, L. Lin, and Y. Zhu
Uniformly carbon-covered alumina (CCA) was
prepared via the carbonisation of sucrose highly dispersed on the alumina
surface. Using special thermogravimetry and sorptometry methods physicochemical
properties of carbon-covered alumina surfaces were investigated. A numerical
and analytical procedure for the evaluation of total heterogeneous properties
(desorption energy distribution and pore-size distribution functions) on the
basis of liquid thermodesorption from the sample surfaces under the quasi-equilibrium
conditions are presented. The desorption energy distribution was derived from
the mass loss Q-TG and the differential mass loss Q-DTG curves of thermodesorption
of pre-adsorbed polar and apolar liquid films. For the first time, the evaluation
of the fractal dimensions of carbon-covered alumina using the sorptometry,
thermogravimetry and AFM data is presented.
Authors:G. Chądzyński, D. Sternik, P. Staszczuk, and B. Kucharczyk
This paper presents possible applications of thermal analysis and sorptomatic methods to study physico-chemical properties
of the high-Tcsuperconductor Y1Ba2Cu3O7-x and perovskite LaCoO3. It is shown that both Y1Ba2Cu3O7-x and perovskite phase are highly sensitive to water vapour. Mechanism of adsorption of water on LaCoO3depends largely on time activation (tact). When the time of water vapour saturation was 0<tact<180 s, physisorption process was observed. In the case of longer times water vapour action, tact>180 s, chemical decomposition was observed.
Authors:P. Staszczuk, M. Błachnio, E. Kowalska, and D. Sternik
Calculations based on the fractal geometry in the estimation of surface
heterogeneity are superior compared with conventional calculation methods
(e.g. from the data of gas adsorption or X-ray radiation scattering) as they
can be applied without limitation as far as the range of surface sizes of
the studied structures is concerned. This paper presents structural characteristics
of carbon and carbon- free nanomaterials based on the determined surface and
volumetric fractal coefficients. Fractal coefficients were determined from
the data obtained by means of two independent methods: sorptometry and atomic
force microscopy (AFM). Correlation between porosity parameters and fractal
coefficients is presented.
Authors:D. Sternik, P. Staszczuk, J. Pękalska, G. Grodzicka, B. Gawdzik, J. Osypiuk-Tomasik, and P. Witer
The adsorption of a polar (water)
and a non-polar (n-octane) liquid on silica
gels, modified by adsorption of proteins, has been studied by thermal analysis.
Silica gels with physically adsorbed BSA and ovalbumin layers were used. Thermodesorption
energies were determined from Q-TG and Q-DTG curves recorded under quasi-equilibrium
conditions. Significant differences in liquid desorption were observed from
the surfaces due to heterogeneous changes (energetic and geometrical) as a
result of modification. These results are compared with those obtained for
the samples heated at 160C for 1 h.