Daftar Isi: Studies in Physico-Chemical Properties of Caseins. Part V. Sorption of Ethanol and Methanol Vapours

Daftar Isi:

Department of Chemistry, Panjab University, Chandigarh-14 Received 30 August 1971 Sorption isotherms of methanol and ethanol on caseins were determined, using a quartz spring balance technique, at 40°. The isotherms permit the application of B.E.T. as well as Harkins and Jura equations. The methanol areas of caseins, as obtained from B.E.T. plots, are in good agreement with the corresponding values reported earlier from water isotherms. The ethanol areas, however, are somewhat lower. The value of k of Harkins and Jura equation for methanol has been shown to be about 3.67 whereas the value for water, reported in the literature, is 3.86. The heats of adsorption as well as free energy changes involved, as calculated from the respective isotherms, decrease in the order; water > methanol > ethanol. The Vm value of methanol and ethanol corresponds to coverage of about 1.5 and 3 ionic sites, per molecule, respectively, as compared to the corresponding value of 1 for water vapour. The results indicate parallel orientation of the adsorbates along casein surface.