Untitled

Abstract

The presence of surfactants may have profound effects on the transport of organic contaminants in multiphase systems. It is a common practice, however, to model the subsurface migration of liquids independently of the aqueous phase composition. As such, transport in these systems may not be adequately characterized. This study investigates the impact of pH on interfacial tension, wettability, and the drainage capillary pressure-saturation relationship in air-water-quartz and o-xylenewater-quartz systems containing dodecylamine, an organic base. In these systems, three mechanisms, speciation, partitioning, and sorption, are important in determining the interfacial tension and contact angle, and consequently, important in determining the capillary pressure. By adjusting the pH above and below, the pK a of the base, the relative importance of these mechanisms was altered. Below dodecylamine's pK a of 10.6, the base was primarily in a cationic form resulting in minimal partitioning into the nonaqueous liquid and greater sorption at the quartz surface. Above the pK a , the base was primarily in a neutral form which did not sorb to the quartz, and, furthermore, partitioned into the organic liquid phase where its surface activity was minimized. The combination of these processes caused the capillary pressure to change in a manner consistent with pore-scale theory of capillarity. The utility in this approach lies in the possibility of predicting transport properties in multiphase systems while incorporating the direct effects of solution chemistry.

Surface and Interfacial Properties of Octanoic Acid–Octylamine Mixtures in Isooctane–Water Systems: Influence of Acid: Amine Molar Ratio and Aqueous Phase pH

“…At equimolar concentrations of Octac and Octam, the equilibrium in Eq. [4] is probably completely shifted to the right, while at other mole fractions of Octac:Octam the concentration of the complex is lower relative to the concentrations of the individual Octac and Octam molecules.…”

“…This indicates that Octac and Octam form complexes in the oil phase according to Eq. [4]. At equimolar concentrations of Octac and Octam, the equilibrium in Eq.…”

“…Aside from its fundamental importance, interest in the topic is, also due to its significance within applications like liquid-liquid extraction (1,2), and as a model system for the study of processes related to subsurface transport of organic waste (3,4), wettability alteration (5), adhesion (6), etc.…”

CO2 Huff-n-Puff after Surfactant-Assisted Imbibition to Enhance Oil Recovery for Tight Oil Reservoirs

“…Fuyang formation initial CA shows that its wettability is intermediate- to oil-wet with a CA of 108°. This initial non-water-wet wettability is ascribed to the asphaltene deposition on the pore surface that changes its wettability . After determination of the initial wettability, surfactant-added fluids with a concentration of 0.3 wt % were employed for CA measurements to evaluate their ability of wettability alteration.…”

Adsorption from the Organic Phase in the Octanoic Acid–Octylamine–Silica System

“…In addition, the simultaneous adsorption from solutions containing mixtures of organic acids and bases has, to our knowledge, not been published previously. Adsorption processes in such systems are interesting due to their relevance as model systems for the study of processes of importance to subsurface transport of organic waste (11,12), wettability alteration (13), adhesion (14), etc. Thus, in this work we have studied the adsorption of octanoic acid (Octac) and octylamine (Octam), both individually and from their mixtures, onto silica from isooctane.…”