Authors:D. Sternik, P. Staszczuk, M. Majdan, A. Gładysz-Płaska, E. Dąbrowska, and K. Bigda
The paper presents physico-chemical properties
of mixed adsorbents in the clinoptylolite (mordenite)/SiO2
system containing 30, 50, 80 mass% zeolite. Adsorption capacity towards polar
(water, butanol) and non-polar (n-octane)
substances as well as total surface heterogeneity (energetic and geometrical)
were determined. Desorption energy distribution functions as well as fractal
dimensions were also determined and compared with the low-temperature nitrogen
adsorption data. Irregular shapes of the curves q=f(Ed)
as well as large values of volumetric fractal dimensions (Df~2.6)
revealed heterogeneous properties of the zeolite/SiO2 system surfaces. Addition
of zeolite increases total heterogeneity of the material.
Authors:D. Sternik, P. Staszczuk, J. Sobieszek, M. Płanda-Czyż, and S. Wasak
The effect of albumin adsorption on neutral
active aluminium oxide was investigated in the presence of polar and non-polar
liquids. The adsorbed values were highest near the isoelectric point of albumin
and varied in the range 5–10 and 3–11 mg g–1
with phosphate buffer and potassium chloride respectively after 2 and 24 h.
In the case of aluminium oxide the effect of albumin adsorption on total heterogeneity
of adsorbents is not explicit. On the one hand, the modified samples showed
decreasing surface area with increase of surface coverage with albumin. On
the other hand, modifications under the same conditions but without albumin
caused similar changes. These effects suggest the strong influence of medium
pH on surface properties (due to surface polarization) and competitive co-adsorption
of ions on the process. The volumetric fractal dimensions of the studied materials
change in the range 2.25–2.32 for pure aluminium oxide and BSA modified
from the phosphate solution. Ed,max
values (desorption energy in the maximum of distribution function) diminish
(in the range 40–45 kJ mol–1) compared
with pure aluminium oxide (Ed,max=52
kJ mol–1) for water thermodesorption at modified
surfaces to the increase of a number of active centers of hydrophobic character,
and weakening of the adsorbent–adsorbate increases.
Authors:P. Staszczuk, M. Planda-Czyz, D. Sternik, M. Blachnio, G. Grodzicka, J. Pekalska, S. Wasak, and K. Pilorz
The paper presents the complex studies of adsorption
and porosity of pure and modified–aluminium oxides samples. The presence
of Mn2+ and Ni2+ modifiers
on the aluminium oxide surface causes increase in water adsorption capacity
and its decrease in the case of benzene and n-octane.
This is due to decrease of specific surface area, volume and radius of pores
as a result of surface impregnation and microcrystals formation during modification
with manganese and nickel chlorides. Microcrystals formation on the surface
and porosity decrease where confirmed by the AFM and SEM studies.
the Q-TG and Q-DTG data, the energies of liquid desorption from the surface
of the samples and the functions of desorption, energy distribution were calculated.
High degree of nonlinearity of the run of the functions resulting from great
heterogeneity of the studied surface was found. Adsorption of cations creates
more homogeneous surface of aluminium oxide, and it is responsible for the
change in adsorbate molecule interaction energy and changes mechanism of adsorption
and desorption as well as thickness and structure of the adsorbed film. From
the experimental data some parameters characterizing adsorption properties
and porosity of the studied samples were determined using the measuring methods
(thermal analysis, sorptomate, porosimetry, AFM).