Water retention by disperse hydrophilic materials as affected by surface tension

Abstract The W 1 /W 2 ratio (W 1 being water retention when using pure water with surface tension γ 1 = 72 mN m −1 , and W 2 being water retention when using 1-hexadecanol solution with surface tension γ 2 = 35 mN m − ) of highly hydrophilic powders like glass, quartz sand and CaSO 4 ·H 2 O, with a contact angle with water θ 1 , and with a contact angle with 1-hexadecanol solution θ 2 = 0°, depends only on the γ 1 /γ 2 ratio: W 1 W 2 = γ 1 γ 2 The W 1 /W 2 ratio for hydrophilic materials with O° 1 /γ 2 = 2 at θ 1 = 0° to 0 at θ 1 = 90°. W 1 W 2 = γ 1 γ 2 cos θ 1 cos θ 2 If θ 2 is O°, then W 1 W 2 = caseγ 1 γ 2 cos θ 1 Due to the inverse relation between γ and cos θ, the following equality applies to materials with W 1 /W 2 → 1, like clay: γ 1 cos θ 1 ≈ γ 2 cos θ 2