Three-Phase Contact Formation and Flotation of Highly Hydrophobic Polytetrafluoroethylene in the Presence of Increased Dose of Frothers

Abstract

The time of a single bubble attachment to a rough hydrophobic solid surface with contact angle greater than 90° in aqueous solutions at different frothers (n-octanol, α-terpineol and N-octyl-trimethylammonium bromide) in the concentration ranges of 10–6 to 10–3 M was compared with flotation performed under corresponding conditions. A relationship between the time of three-phase contact (TPC) formation at the bubble/liquid/solid interface and flotation rate was obtained. It was found that above a certain frother dose, irrespective of frother type, one could observe significantly longer bubble–solid surface attachment time, which increases from about 2 ms to above 50–60 ms for higher frother concentrations. Accordingly, the flotation rate for the corresponding frothers concentrations decreased from ca. 0.8 s–1 to values below 0.01 s–1. The obtained results confirm that air can be entrapped at rough highly hydrophobic solid surfaces and show the importance of the bubble attachment time for the flotation kine...