ADSORPTION OF LIQUIDS AND SWELLING OF WOO D .1. ADSORPTIVITIES OF SOME ORGANIC LIQUIDS ONTO PRESWOLLEN WOOD

This series of studies deals with the swelling mechanism of wood by va rious kinds of liquids from the aspect of the adsorptivities of the li quids onto wood. This first paper deals with the adsorptivities of eig ht organic liquids onto preswollen wood from their solutions of nonpol ar solvents which were studied thermodynamically. Adsorption isotherms , shown with reference to mole fractions, indicate a wide variety of a dsorptivities among the test liquids, and liquids having large positiv e deviations of activities in their solutions, differing from the idea l behavior of solutions, tend to have greater adsorptivities. However, adsorption isotherms, shown with reference to activities, diminished in a wide variety of adsorptivities. These results mean that the adsor ptivity judged from the adsorption isotherms shown with reference to m ole fractions are influenced largely by the interaction between adsorb ates and solvents, so that adsorptivities of adsorbates for adsorption sites should be evaluated from adsorption isotherms shown with refere nce to activities. Standard free energy changes of adsorption, as a th ermodynamic measure of adsorptivity, were determined by means of Langm uir's adsorption theory. The values for liquids having both proton acc epting and donating properties were smaller than those for liquids hav ing only a proton accepting or a donating property. These results show that adsorptivities of liquid adsorbates onto adsorbents are because of the withdrawal of the liquid molecules from the cohesion in the pur e liquid state. The values of the free energy change of adsorption of the test liquids did not correspond to the swelling of the wood in the liquids almost at all. It should be recognized that molecular sizes o f liquids need to be taken into consideration in the study of relation ships between the adsorptions of liquids onto wood and the swellings o f wood in the liquids.