Heats of immersion of alpha and gamma alumina

Abstract

The heats of immersion of a-AI203 and y-Al2O3 in water, benzene, five n-butyl derivatives, and an epoxy resin in benzene, have been determined at 25°C. Values for the heats of immersion of alumina on substrate aluminium in the same liquids have been recalculated, and they show that the immersional properties of this solid approximate to those of y-Al2O3. Immersion of all three solids in water, a-Al2O3 in n-butyraldehyde and y-Al2O3 in n-butyl alcohol, give rise to high heats, which are indicative of a contribution from chemisorptive processes. The catalytic activities of the solids for parahydrogen conversion at 77°K have also been determined. The results are discussed in relation to current ideas on imersional processes and the surface properties of alumina.The measurement of heats of immersion of solids in liquids permit the investigation of a number of the properties of the solid surface. The thermodynamics of the immersion process, developed by Harkins,l has been reviewed by Eley 2 from the viewpoint of adhesion. Both the integral and differential heats of adsorption of vapours on solids can be determined from heats of immersion. The results of Hollabaugh and Chessick,3 on the adsorption of vapours on rutile, illustrate the close agreement that can be obtained between isosteric heats and those from immersion data. Zettlemoyer and coworkers 4 9 5 have shown that the variation in the heat of immersion of a solid in a series on n-butyl derivatives of differing dipole moment can be used to estimate an average value for the electrostatic field strength at the solid surface.The present contribution reports an investigation of the surface properties of welldefined alpha and gamma alumina by the heat of immersion technique. To permit a direct comparison between the present results and those for aluminium oxide on substrate aluminium,6 the aluminas were given the same outgassing treatment. It is doubtful whether evacuation for 72 h at 300°C and < 10-6 mm Hg removed all surface water,7* 8 but reproducible surfaces were obtained. The majority of the heats of immersion were determined using pure liquids, but benzene solutions (5 % by weight) were used with n-butyl alcohol, n-butyraldehyde and the epoxy resin, Araldite 6100. EXPERIMENTAL A P P A R A T U S

Estimation of the interfacial tension of biological cells by the contact angle method

“…Recently, an immiscible phase method developed by Albertson20 has also been used to obtain contact angles on cell layers. 4,21 Present results show that it is difficult to eliminate surface tension reduction for a water drop contacting a biological surface and the relation ylv < ylv0 will hold for most cases. Consequently, the simultaneous determination of both contact angle and surface tension under these experimental conditions is a necessary extension to current practice.…”

Vacuum-Deposited Thin Film of Linear π-Conjugated Poly(arylene)s. Optical, Electrochemical, and Electrical Properties and Molecular Alignment

“…The trend observed for the order of the perpendicular orientation of PPP (eq 2) also seems to be accounted for on the basis of surface energy or strength of interaction between PPP and the substrate. It has been reported that the heat of wetting H w of carbon, aluminum, and copper in benzene, which corresponds to the monomer unit of PPP, increases in the following order: 31 The large H w value of Cu seems to originate from π-coordination of benzene to the transition metal, and a number of π-benzene complexes of various transition metals including Cu and Ag have been isolated. 32 Thus, the higher order of the perpendicular orientation of PPP on the carbon substrate seems to be attributable to the weaker interaction of the PPP molecule with carbon.…”

Direct interfacial polymerization onto thin ceramic hollow fibers

“…To increase the amount of hydroxyl groups [26], and to allow for a larger reactant reservoir in ∼ 5 nm small pores, the fibers were coated with γ-alumina atop of the AKP-30 smoothing layer. The use of γ-alumina intermediate layers has been studied elaborately for, for instance, the fabrication of high performance inorganic gas separation membranes [27].…”