Authors:A. Nasser, M. Gal, Z. Gerstl, U. Mingelgrin, and S. Yariv
The adsorption of the tertiary aromatic amide alachlor by Na-montmorillonite and Al-polyhydroxy-montmorillonite was investigated
by DTA, XRD, SEM and Thermo-FTIR Spectroscopy. This molecule is adsorbed into the interlayer space of the montmorillonite,
replacing interlayer water. In this organo-clay complex the interlayer water forms hydrogen bonds with N or O atoms of the
tertiary amide group. Samples which were aged during six months degraded by hydrolysis to give mainly secondary amide. This
reaction was catalysed by Al-polyhydroxy-montmorillonite more than by Na-montmorillonite.
Jntti introduced a method to reduce the time required for the stepwise measurement of adsorption isotherms. After each pressure
change he measured the adsorbed mass three times and calculated its equilibrium value at the new pressure. In the present
paper, we discuss the applicability of this method in a broader scope without starting from a given combination of sorptive
and adsorbent and the influence of measuring inaccuracies. The method is applied to detect whether the adsorption process
is based on more than one adsorption mechanism or not.
The influence of microporous carbon surface oxidation on energetics of methane adsorption at 308 K is discussed. Obtained
adsorption heats and integral molar entropies of the adsorbate show that microporous carbon surface oxidation changes the
methane adsorption process. This is probably resulted by the existence of an endothermic effect during adsorption in oxidized
Authors:G. Yurchenko, A. Matkovsky, A. Shimansky, and A. Chuiko
Adsorption of n-pentane, triethylamine, diethyl ether, acetonitrile and chloroform has been investigated on pyrogenic alumina (S=140 m2 g−1). The results of our studies have shown the presence of active sites on the surface of pyrogenic alumina with irreversible
adsorption of electron-donating molecules and CHCl3 and the dependence of energetic surface properties on electronic structure of adsorbate, quantity of adsorbed substance and
hydration degree of the surface. On the hydrated oxide surface the water molecules screen the active sites of the surface,
which resulted in changing of interaction energy of adsorbent-adsorbate and decreasing the region of irreversible adsorption
of organic bases and CH-acid.
Authors:P. Gauden, G. Rychlicki, A. Terzyk, and R. Wojsz
A new adsorption isotherm equation based on the extension of the potential theory of adsorption on microporous fractal solids
and corresponding thermodynamic functions were formulated and applied for description of the experimental data of adsorption
on a microporous carbon. The comparison of the obtained results with the original Dubinin-Astakhov equation is presented.
In this paper the dependence of thermodynamic functions (the differential molar enthalpy of adsorption ΔH and the differential
molar entropy of adsorption ΔS) on the fractal dimension D are discussed, as well.
DSC and TG-DTA techniques were used to investigate micro-sized silver powder particles and the adsorption of ethyl cellulose
on these particles in a solution of ethyl acetate. The apparent specific heat of the silver particles was determined, and
the kinetics of temperature-programmed desorption (TPD) of these adsorbed silver particles was investigated. Results show
that the apparent specific heat and desorption kinetic parameters obtained by thermal analysis techniques could be used to
characterize certain physico-chemical properties of such a particulate system.
Authors:J. Poulis, E. Robens, C. Massen, and G. Reichenauer
Jntti introduced a method to calculate the adsorption equilibrium by measuring the actual adsorbed amount three times after
a change to the gas pressure. By this method the experimental time for adsorption measurement can be considerably shortened.
The procedure was developed for use in adsorption measurements where the adsorbed masses are directly measured with a balance.
In the present paper we will demonstrate that the method is particularly useful in volumetric (manometric) measurements.
Specific surface area and pore size distribution are determined usually from adsorption isotherms at low temperatures using
nitrogen or noble gases. These are not absolute parameters and the measuring methods are fraught with serious difficulties.
General problems of sorption measurements and recent developments are discussed. To obtain information for practical purposes
these measurements need to be supplemented by investigations of the sorbate/sorbent system used in practice. Results of the
measurement of nitrogen and water vapour adsorption on different materials are compared.