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Thermodynamics of methane adsorption on the microporous carbon adsorbent ACC

“…(1) takes the fol lowing form: (2) where z = pv g /(RT) is the compressibility coefficient of the gas phase at the pressure р, temperature Т, and specific volume of the gas phase v g ; R is the universal gas constant; v(a,T) = V 1 (a,T)/m 0 is the specific reduced volume of the adsorbent-adsorbate adsorption system (m 0 is the weight of the degassed adsorbent); а is the amount adsorbed defined as the total content of the substance in the adsorbent field.…”

“…1 On the basis of the dependences of similar thermodynamic functions on the adsorption equilibrium parameters one can judge about both the state of the adsorbent-adsorbate system and changes of the adsorbate in pores of the solid body and the adsorbent itself. 2 In the framework of the study of the general regularities in the behavior of the thermodynamic functions of the adsorption systems it seems most interesting to examine the adsorbents with a narrow pore size distribution and the chemical state of the surface close to homogeneity. This makes it possible to analyze the changes in the thermody namic functions of the adsorption system for a specified pore structure, i.e., for a certain adsorption mechanism.…”

The role of adsorption compression in nanocapillarity

“…These internal forces were noticed in experiments with ceramic nanoparticles [32,33]. Systematic experimental studies of such forces were performed by high-precision measurements of expansion of various nanoporous solids loaded with fluid adsorbates [34][35][36][37][38]. These include nanoporous glass [34], zeolites [35], nanosilicates [36] and activated carbons [37].…”

“…5 and 6 illustrate that oscillatory adhesion forces [39,43] and phenomenon of adsorption compression [13][14][15][16][17] have the same thermodynamic origin. Note that adsorption compression results in significant internal forces when various fluid molecules are adsorbed in pores of solids [32][33][34][35][36][37][38]. These forces have the same nature as oscillatory adhesion forces; the difference is that there is a distribution of pore sizes and oscillations are averaged.…”

“…Experimentally, it is difficult to vary pore sizes in an accurate, controllable way and measure internal forces as functions of pore sizes. However, these internal forces do exist causing expansion of crystalline solids such as porous glass [34], zeolites [35], silicates [36], and activated carbon [37].…”