Interaction of Ionic Species and Fine Solids with a Low Energy Hydrophobic Surface from Contact Angle Measurement

Influence of Aqueous Electrolytes on the Wetting Behavior of Hydrophobic Solid Polymers—Low-Rate Dynamic Liquid/Fluid Contact Angle Measurements Using Axisymmetric Drop Shape Analysis

“…They are also in line with the results of Zhou et al (9), who already suggested the absence of specific adsorption of the examined ions on hydrophobic paraffin wax, based upon the observed wetting behavior. According to Zhou et al, the low surface energy of the polymer (surface energy of paraffin wax is 25.5 mJ/m 2 (42)) prevents specific adsorption of ions, which would result in an energetically unfavorable increase of the total system energies.…”

“…For the polymers studied so far the effect of salt concentration and pH on water contact angles is controversially discussed. Zhou et al (9) investigated the interaction of ionic species with a low-energy hydrophobic surface using model systems of paraffin wax in aqueous solutions of metal chlorides at different pH levels. They observed a relatively constant water contact angle, irrespective of the type and concentration of metal chloride and the pH value of the solution.…”

Understanding Water‐Based Bitumen Extraction from Athabasca Oil Sands

“…However, due to the complex bitumen extraction process, some fine solids unavoidably report to the bitumen froth. In terms of thermodynamic criteria, hydrophilic solids (i.e., with zero water contact angle) would not coat on or attach to hydrophobic oil or bubble surfaces (Zhou et al, 1998). The following factors can account for the fine solids and clays reporting to the bitumen froth: a) Entrainment of fine solids (clays) in water carried over to the bitumen froth; b) Entrapment of fine solids (clays) between bitumen droplets attached to a bubble; c) Slime coating on bitumen droplets; and d ) Attachment of fine solids to bubbles due to changes in solid s u rface properties by adsorbed surfactants.…”

“…Although bitumen contains both soluble species (e.g., carboxylates and sulphonates) and insoluble surface-active species (e.g., higher molecular weight carboxylates, and asphaltenes), it is generally accepted that the accumulation of natural water-soluble surfactants at bitumen/water interface can interfere with bitumen/bubble attachment and bitumenbitumen coalescence, which in turn stabilizes water-in-oil emulsion (Zhou et al, 1998;Yan et al, 1999;Masliyah, 2003;Zhou et al, 2004a). However, recent studies (Gu et al, 2002) suggested that complete removal of the water-soluble surface active species from bitumen by continuous water extraction resulted in an increased stability of bitumen droplets and the formed emulsion.…”

Experimental studies of contact angle hysteresis phenomena on polymer surfaces — Toward the understanding and control of wettability for different applications

“…Assuming a very thin electrolyte-free water layer, the properties directly at the polymer/liquid interface and the air/liquid interface and consequently the contact angle would not change significantly. A possible explanation of this behavior is that the low surface free energy of the polymers prevents specific adsorption of ions, which would result in an energetically unfavourable increase of the total system energies [65]. In contrast, surfaces with ionizable functional groups may be charged by direct specific interactions with ions that modify the properties of the solid surface itself.…”