Some theoretical and experimental limitations in the determination of surface free energy of siliceous solids

Effect of electrolyte on surface free energy components of feldspar minerals using thin-layer wicking method

“…The same values determined by Giese et al [33] for ground glass using TLW are γ LW = 31.1, γ + = 0.4, and γ − = 37.1 mJ/m 2 . Bilinski and Holysz [11], listed the literature data on the components determined from contact angles or TLW for various siliceous solids in the range of γ LW = 28.6-44.9, γ + = 0.0-0.1, and γ − = 8.9-62.4 mJ/m 2 ; these are comparable to our results.…”

“…Washburn, about a century ago, developed the Washburn equation for capillary and friction forces [11][12][13][14]. Bartell and Whitney [15] used this equation to determine the contact angles by the capillary rise method in the 1930s.…”

“…Chibowski and co-workers presented theoretical derivations on different substrates [3,4,13,[16][17][18][19] by considering the other forces influencing the rate of rise. The TLW method for measuring the contact angles of powdered materials was successfully applied to all minerals, even those with irregular shapes, including nonswelling clays [20], talc [12,[20][21][22], dolomite [21], basalt [13], limestone [13], a variety of silicates [11,20,[23][24][25], and the cuboids hematite, kaolin [20], calcite [21,24,25], anatase [22], alumina [12], hydroxyapatite [26], octacalcium phosphate [26], fluorapatite [26], various hydrotalcites [12], and muscovite [12].…”

A Novel Method for Surface Free-Energy Determination of Powdered Solids

“…(4)(5)(6)(7)(8). The values of both apolar and acid-base components are in the range of values found in the literature for different silicaoriginating solids (8,(17)(18)(19)(20)(21)(23)(24)(25)(26)(27). However, the range of the components is so broad that, in fact, it is always possible to find similar values.…”

Ranking proposed models for attaining surface free energy of powders using contact angle measurements

“…Due to the immobility of molecules in a solid phase, solid surface tensions are difficult to measure directly [5]. Hence, in order to estimate the surface free energy of a powder various indirect methods have been developed [6][7][8][9][10][11][12][13][14][15]. Some are based on measuring the contact angle of a liquid on the compressed disc of the powder under test [6,7], whilst others use inverse gas chromatography [8,9], adsorption gas chromatography [10,11], parameters of dissolution and/or crystallization [12,13] and contact angle measurement of different liquids using the modified Lucas-Washburn's equation [14,15].…”