Calorimetry of Adsorption

AQ is the integral heat of adsorption evolved during the finite increment [6,31] k is a calibration constant 

AT is the difference between thermostat temperature and the sample temperature during adsorption t is time [50] 

The Physical Chemistry of Materials Energy and Environmental Applications 

FIGURE 6.3 Schematic representation of a calorimeter and a volumetric system. 

The differential heat of adsorption was calculated with the help of Equation 6.8 in increment form 

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In a broad sense, an acid site can be defined as a site on which a base is chemically adsorbed. Conversely, a basic site is a site on which an acid is chemically adsorbed. Specifically, a Bronsted acid site has a propensity to give a proton, and a Bronsted base has the tendency to receive a proton. Additionally, a Lewis acid site is capable of taking an electron pair and a Lewis basic site is capable of providing an electron pair. These processes can be studied by following the color modifications of indicators, and by using infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies, and calorimetry of adsorption of the probe molecules (see Chapter 4). 

The adsorption of ionic surfactants onto mineral substrates is a complex phenomenon simultaneously controlled by the nature of the adsorbing species, the properties of the solid surface and the composition of the aqueous solution. As a consequence, there is no complete theoretical model which can describe, both qualitatively and quantitatively, all the experimental information available. Calorimetry of adsorption may be very useful in studying the nature of the interactions in the adsorption system, but alone it is not capable of solving satisfactorily many detailed problems which still remain to be explained. Hovewer, the evolved model of the phenomenon should be able to contain the experimental results from all the bulk, calorimetric and spectroscopic studies reported on the system. 

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