Volume filling, during adsorption

IUPAC defines the lower limit of mesopores as 2 nm [1] which was considered as the limit below which the adsorption will occur by volume filling. However, in our recent article, based on the tensile stress hypothesis, we have shown that this limit is different than IUPAC limit. Using the mechanical stability criterion for the cylindrical meniscus (during adsorption), the critical size is obtained from... 

Dubinin and coworkers, during the course of their extensive studies on activated carbons, have developed the so-called theory of volume filling of micropores. Based on numerous experimental data, Dubinin and collaborators have added a second postulate to the Polanyi theory, which complements it. For an identical degree of filling of the volume of adsorption space, the ratio of adsorption potentials for any two vapors is constant ... 

As it can be seen, the main features that are observed in the actual experiment are obtained. The activity increases sharply from during a very short time interval, corresponding to the filling of the reactor volume and the adsorption of the first species on the surface of the catalyst. After this induction period, which is very short and depends mainly on the rate of the... 

Kadlec, O., Mechanisms of volume filling of micropores during adsorption of vapours, Adsorpt, Sci. Technol., 1(2), 133-150(1984). 

The grey zone in this figure represents the volume of activated carbon at the bottom of the bed. During adsorption, the temperature in this zone will increase at a rapid rate as exothermic adsorption occurs. As sites are filled with solvent molecules and the adsorbent rate declines, so also does the rate of temperature increase. Completion of the bed s use may be recognized by comparing the response of the temperature sensor in the bottom bed volume to a fixed reference value over time, or by use of an integrating transducer to continuously calculate the rate of temperature change with time and compare that to another fixed reference value. 

During the adsorption or occlusion of various molecules, the micropores fill and empty reversibly. Adsorption in zeoHtes is a matter of pore filling, and the usual surface area concepts are not appHcable. The pore volume of a dehydrated zeoHte and other microporous soHds which have type 1 isotherms may be related by the Gurvitch rule, ie, the quantity of material adsorbed is assumed to fill the micropores as a Hquid having its normal density. The total pore volume D is given by... 

Finally, the capacity of activated carbons to adsorb surfactants in dynamic conditions has been evaluated. Dynamic adsorption has been carried out in filter columns (diameter 29 nun) in conditions proposed in France [39] bed depth - 6 cm, graining of carbon 0,6—1,2 mm, filtration rate — 6 m/h. Colunuis have been filled with 3 fractions of carbon grain in equal volumes (the total volume of carbon - about 39.6 cm ). Carbons have been flooded with water and then de—aerated in vacuo during Ih. Adsorption has been carried out by passing solution of sodium laurylosulphate SLS (1 mg/dm ) through the bed. 

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