Time-dependent changes of adsorption and wetting properties of pillared montmorillonites
Authors: Dékány, I.; Seefeld, V.; Lagaly, G.
Source: Clay Minerals, Volume 35, Number 5, 1 December 2000 , pp. 763-769(7)
Publisher: Mineralogical Society
Abstract:The changes of adsorption properties of uncalcined Al-pillared montmorillonite were studied. A soda-activated bentonite from Slovakia was reacted with polymeric hydroxoaluminium salt solutions. During storage in air at room temperature for three years, the basal spacing decreased by 0.15 0.2 nm; the specific surface area was reduced by 80% and the total pore volume by 40-60%. Adsorption experiments from ethanol-cyclohexane mixtures revealed the decreasing adsorption capacity and the increasing hydrophobicity. The changing surface character was also evident in the decrease in enthalpy of immersion in ethanol from 65.3 J/g to 8.3 J/g (sample B) and from 37.8 J/g to 5.2 J/g (sample C). The alteration probably arises from gradual formation of gibbsite-like interlayers and the redistribution of charges.
Document Type: Research Article
Publication date: December 1, 2000