Sandwich Structures at Oil–Water Interfaces under Alkaline Conditions

• Published in: Journal of colloid and interface science Vol. 253; no. 2; pp. 427 - 434
• Main Authors: Horváth-Szabó, Géza, Czarnecki, Jan, Masliyah, Jacob H.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 15.09.2002; Elsevier
• Subjects: Chemistry; Exact sciences and technology; Gas-liquid interface and liquid-liquid interface; General and physical chemistry; Surface physical chemistry; emulsion stability; crude oil; enhanced oil recovery; bitumen; naphthenates; interface elasticity; polarization microscopy; flooding models, naphthenic acids; liquid crystal; Interfacial layer; Water oil emulsion; Naphthenic acid; Hydrocarbon; Crude oil; Stabilization; Liquid liquid interface; Sandwich structure; Aqueous solution; Experimental study; Liquid crystals; Sodium hydroxide
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1006/jcis.2002.8524

Equilibrium liquid crystal (LC) layer on an interface between crude oils and water was observed at high pH. This layer is composed mainly of sodium naphthenates produced in situ at the water/oil interface. Transient LC layer was also evolved at the interface of aqueous phase of sodium hydroxide solutions and oleic phase of naphthenic acid (NA) solutions as result of a chemical reaction between NaOH and NA. This chemical reaction causes transport process resulting in a disturbance of the interface. Optical observation of this interface disturbance reviled that the interface covered with LC shows considerably lower flexibility as compared to LC free interface. The LC layer eventually dissolves in the water phase at low oil-to-water ratio, while at high oil-to-water ratio it can form an equilibrium phase, which spreads spontaneously at the oil–water interface.