Acta Phys. -Chim. Sin. ›› 2002, Vol. 18 ›› Issue (01): 62-65.doi: 10.3866/PKU.WHXB20020114

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Stoichiometric Displacement Model for the Adsorption of Propionic Acid and nButyric Acid by Silica Gel from Aqueous Solution

Chen Yu-Yin;Liu Fan   

  1. Department of Chemistry, Leshan Teacher′s College, Leshan 614004
  • Received:2001-06-11 Revised:2001-08-22 Published:2002-01-15
  • Contact: Chen Yu-Yin

Abstract: The adsorption of propionic acid and nbutyric acid from aqueous solution by silica gel has been studied at 293,303 and 313 K respectively.It was found that the adsorption obey stoichoimetric displacement model for adsorption at liquidsolid system (SDMA). The thermodynamics and mechanism of adsorption processes were studied on the basis of linear parameter from SDMA. The adsorption is a spontaneous, exothermic process of reduced entropy. Standard free energy change for the adsorption of nbutyric acid is larger than that of propionic acid. Standard enthalpy change for the adsorption of nbutyric acid is smaller than that of propionic acid. The equation of free energy change for adsorption was derived.

Key words: Silica gel, Adsorption, Propionic acid, n-Butyric acid,  Stoichiometric displacement model for adsorption, Adsorption thermodynamics