Components of Surface Free Energy of Some Clay Minerals

Abstract

Abstract--The wetting contact angle was measured for water drops settled on the surface of pressed discs of kaolinite, alumina, bentonite, marble, montmorillonite, and quartzite immersed in hexane, octane, dodecane, cis-decalin, and air. Minimum and maximum values of the contact angle were obtained for the given systems of solid-water drop-hydrocarbon, depending on the manner of disc preparation. Using both minimum (0min) and maximum (0m~x) values of the contact angle, values of the dispersion component (3,s ~) of surface free energy of these solids were calculated from the equation which was derived on the basis of an equilibrium state of the system solid-water drop-hycrocarbon for two different hydrocarbons. The values of3,s ~ for kaolinite, alumina, bentonite, marble, montmorillonite, and quartzite obtained from Oma, are 83.5, 98.1, 98.9, 80.2, 95.9, and 89.7 mJ/m 2, and from Om~x are 73. 1, 85.0, 84.4, 75.8, 85.5, and 75.5 mJ/m 2. These values for marble and quartzite are similar to those in the literature (marble = 67.7 mJ/ma; quartzite = 71.3 and 76.0 m J/m2). The values of the dispersion components of surface free energy for marble and quartzite covered with a water film (q, sf a) were found to be: 41.8, 36.9; 49.2, 42.5; 49.6, 42.2; 40.2, 38.1; 48.1, 42.8; and 44.9, 38.0 mJ/m 2, respectively. Values of ~/s~ for kaolinite, bentonite, and montmorillonite agreed well with those obtained from hydrocarbon adsorption isotherms determined by differential thermal analysis (35.5, 36.5, and 37.4 mJ/m2).Using values of ~/sf ~ and contact angles measured in the system solid-water drop-air, the nondispersion component of the surface free energy of solids with adsorbed water film (~sr n) was calculated from the modified Young equation. The values of ~sf" for kaolinite and quartzite are as follows: 55.8, 69.0; 85.6, 94.0; 52.1, 75.0; 64.7, 68.9; 54.9, 71.3; and 59.2, 74.4 mJ/m z. The values of the nondispersion components determined for kaolinite, bentonite, and montmorillonite agreed well with those obtained by differential thermal analysis (67.6, 78.3, and 65.5 mJ/m 2, respectively). Further, based on the assumption that the adsorbed water film decreased the surface free energy of these solids by the value of the work of spreading wetting, the nondispersion component ('ys n) of the surface free energy of the solids was calculated to be: 86.9, 129.6; 169.5,187.7; 67.1,144.8; 117.5,129.3; 83.0, 135.7 and 100.2, 143.4 mJ/m 2. These calculated values of the nondispersion component of marble and quartzite surface free energy agree with those obtained from adsorption isotherms determined by chromatographic and differential thermal analysis (marble = 103.8, 106.4; quartzite = 112, 115, 153.6 mJ/m2).

Pre-activation of ice-nucleating particles by the pore condensation and freezing mechanism

“…Rather low values of equal to or less than 30 • were found for several clay minerals (Janczuk and Bialopiotrowicz, 1988). In order to estimate the effect of a non-zero contact angle, we have redone our calculations for a contact angle of 30 • .…”

Interactions between Talc Particles and Water and Organic Solvents

“…Many authors have tried -Talcs are highly polar compounds essentially because to quantify this phenomena. B. Janczuk et al (57) have of their high surface acidity. shown the decrease of the surface tension of alumina and -In the presence of ambient moisture, the acid sites are quartz as a function of moisture.…”

Wettability study of organic-rich solids separated from Athabasca oil sands

“…Preliminary adhesion measurements were performed on all three humic matter samples with a water-methanol suspending liquid surface tension range of 25-72 dyn/cm. These tests indicated that the surface tensions of all three samples were between 35 and 50 dyn/cm.…”