Adsorption of Liquids and Swelling of Wood. Part VI. Saturated Amounts and Some Thermodynamic Values of Adsorption

Abstract

To understand the swelling phenomenon of wood in liquids, the saturated amount of adsorption of liquids onto wood and the standard free energy changes of the adsorption were determined. The saturated amount of adsorption obtained by regression for several liquids decreased with increasing molecular size of the solvents. The mechanism of wood swelling is discussed systematically taking all the liquids examined in previous experiments into account. Since methanol molecules require more energy for release from cohesive interactions within bulk liquids in the adsorption onto pre-swollen wood, the values of free energy change of adsorption for methanol were lower than the values for acetone, although the relative swelling with methanol was higher. These results suggest that although the cohesive interaction within the bulk liquids reduces adsorptivity, the phenomenon of wood swelling is influenced not only by monolayer adsorption but also by multilayer adsorption. Therefore, the cohesive interaction within the bulk liquids reduces adsorptivity but enhances the condensation which strongly influences the swelling of wood. KeywordsAdsorption Wood swelling Organic liquids Saturated amount of adsorption Standard free energy change Standard enthalpy change Brought to you by | HEC Bibliotheque Maryriam ET J.

Hygroscopic properties of six tree species with four tangential thicknesses

“…With the increase of RH, the EMC of Quercus spp. and X. melanoxylon gradually became smaller than that of Z. schneideriana and Carpinus L, which may be due to the high density and extract content, resulting in low expansion rate and reduced multi-layer molecular adsorption (Morisato et al 2002). The EMC of Carpinus L was always lower than that of Z. schneideriana because the content of Z. schneideriana holocellulose was high and the crystallinity was lower than that of Carpinus L. In phase D, the EMC of the four kinds of wood decreased with the increase of tree species density, which may be due to the minimum density of Z. schneideriana and the high content of holocellulose.…”

“…and X. melanoxylon have higher wood density, high extractives content, and compact structure. When the sample thickness increases, it is difficult for water to enter the wood, with less hydrogen bond fracture and volumetric expansion produces fewer cracks (Mantanis et al 1994;Morisato et al 2002), resulting in reduced EMC.…”

“…and X. melanoxylon have higher wood density, high extractives content, and compact structure. When the sample thickness increases, it is difficult for water to enter the wood, with less hydrogen bond fracture and volumetric expansion produces fewer cracks(Mantanis et al 1994;Morisato et al 2002), resulting in reduced EMC.The increase of EMC in phase D of the moisture absorption test was much greater than that in phases A, B, and C. The possible explanation is the adsorption of free water in the capillary(Hill 2006). The other explanation is related to the glass transition of hemicellulose(Vrentas and Vrentas 1991;Thygesen et al 2010) and the water molecular…”

Swelling of acetylated wood I. Swelling in organic liquids

“…Meanwhile Mantanis et al 4,5 performed a precise measurement on the swelling rate of wood in various liquids and they concluded that the apparent activation energy in the swelling process well corresponded to that for the scission of internal hydrogen bonds among wood constituents. In recent thermodynamic approaches by Morisato et al [6][7][8] they discussed the cohesive interaction within the bulk liquids in the phased adsorption processes of wood. Although the correlations between wood swelling and liquid properties are not always clear, it is generally accepted that the swelling of wood involves competitive processes of the adsorption by hydrogen bonding and the scission of internal hydrogen bonds between the amorphous molecules of wood constituents, therefore it depends on the hydrogen bonding properties of liquids.…”