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Abstract  

Jäntti published in 1970 a method to obtain equilibrium values at an early stage of gravimetric sorption measurements. In former papers the authors criticised and extended that method. In the present work we discuss problems of its applicability on practical measurements.

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Abstract  

The time for adsorption measurements can be substantially reduced by measuring several values at short time intervals at the beginning of the kinetic curve and extrapolation of the equilibrium value. The method used by Jntti for simple adsorption processes has been extended for complicated processes using a second order differential equation. A simulated example is calculated.

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Abstract  

A new approach is presented to determine the dimensions of cylindrical nanopores from adsorption measurements.

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Abstract  

Jäntti introduced a method to calculate the adsorption equilibrium by the measurement of the actual adsorbed amount at three times after a change of the gas pressure. He applied that method for gas/solid systems in which simple adsorption processes occur and for an infinite number of adsorption sites. In the present paper we discuss the case that the number of sites is decreasing with increasing coverage.

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Abstract  

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.

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Abstract  

Jntti et al. published a method to reduce the time necessary for adsorption measurements. They proposed to extrapolate the equilibrium in the stepwise isobaric measurement of adsorption isotherms by measuring at each step three points of the kinetic curve. For that purpose they approximated the kinetic curve by an exponential function which they derived empirically from there measurements. In the present paper we discuss the applicability of the method for adsorption measurements under continuously varying gas pressure.

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Abstract  

Several decades ago, when working in the field of magnetism, we had to use a balance the sensitivity of which was limited only by Brownian motion. This balance was a very slow one and to calculate the moment of force measured by it we used its equation of motion, T=Jα+kα+Cα, where we measured the values of all the quantities present on the right-hand side of this equation. At the 21st Conference on Vacuum Microbalance Techniques in Dijon, we suggested that, with the help of a computer, this procedure could also be made applicable to the handling of fast balances. The present paper contributes to this topic by presenting a computer simulation of such a fast balance.

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Abstract  

At the 3rd Conference on Vacuum Microbalance Techniques in Los Angeles in 1962, we suggested the use of the equation of motion of a balance T=J+α+kα+Cα for the calculation of the unknown torque T, and the measurement for that purpose of the values of all the other quantities in this equation. The present paper discusses the consequences of two sources of error relevant for this method. First, the errors caused in the first and second derivatives of the deflection are considered, deduced from two or three deflection measurements separated by small time intervals. Secondly, the consequences of the errors caused by the uncertainties in the deflection measurements are discussed. Consideration of the two errors together leads to an optimal set of values of parameters for the balance handling.

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Abstract  

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.

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Abstract  

On the basis of a molecular model for adsorption kinetics Jntti introduced a method to calculate equilibriums shortly after a change of the pressure of the sorptive gas. In the present paper we show that this method is useful in many more situations than those intended originally.

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