TY - JOUR

T1 - Ionic hydration-induced evolution of decane-water interfacial tension

AU - Wen, Boyao

AU - Sun, Chengzhen

AU - Bai, Bofeng

AU - Gatapova, Elizaveta Ya

AU - Kabov, Oleg A.

PY - 2017/6/14

Y1 - 2017/6/14

N2 - Building a connection between the variations in interfacial tension and the microstructure of the oil-water interface is still very challenging. Here, we employ a molecular dynamics method to study the effect of monovalent ions on the decane-water interfacial tension and reveal the relationship between ionic hydration and the variation of interfacial tension. Our results indicate that interfacial tension presents a non-monotonic dependence on the ionic concentrations owing to the distinctive adsorption characteristics of ions. At low ionic concentrations, the hydration of the discrete ions at the interface causes an enhancement in the virial term of the interfacial tension, resulting in an increase of the interfacial tension with increasing ionic concentrations. At high ionic concentrations, the ion pairs at the interface weaken the ionic hydration, thus the virial term of the interfacial tension decreases and the interfacial tension decreases slightly. In addition, the kinetic energy term of interfacial tension increases only with increasing temperature, while the virial term decreases with an increase in either temperature or pressure on account of the weakening ionic hydration; therefore, the increase of temperature and pressure induces different degrees of the decrease in the interfacial tension owing to the major contribution of the virial term, particularly at high ionic concentrations.

AB - Building a connection between the variations in interfacial tension and the microstructure of the oil-water interface is still very challenging. Here, we employ a molecular dynamics method to study the effect of monovalent ions on the decane-water interfacial tension and reveal the relationship between ionic hydration and the variation of interfacial tension. Our results indicate that interfacial tension presents a non-monotonic dependence on the ionic concentrations owing to the distinctive adsorption characteristics of ions. At low ionic concentrations, the hydration of the discrete ions at the interface causes an enhancement in the virial term of the interfacial tension, resulting in an increase of the interfacial tension with increasing ionic concentrations. At high ionic concentrations, the ion pairs at the interface weaken the ionic hydration, thus the virial term of the interfacial tension decreases and the interfacial tension decreases slightly. In addition, the kinetic energy term of interfacial tension increases only with increasing temperature, while the virial term decreases with an increase in either temperature or pressure on account of the weakening ionic hydration; therefore, the increase of temperature and pressure induces different degrees of the decrease in the interfacial tension owing to the major contribution of the virial term, particularly at high ionic concentrations.

KW - MOLECULAR-DYNAMICS

KW - CRUDE-OIL

KW - LIQUID/LIQUID INTERFACES

KW - LOW-SALINITY

KW - X-RAY

KW - SURFACTANT

KW - NANOPARTICLES

KW - TEMPERATURE

KW - TRANSPORT

KW - SYSTEMS

UR - http://www.scopus.com/inward/record.url?scp=85024132240&partnerID=8YFLogxK

U2 - 10.1039/c7cp01826f

DO - 10.1039/c7cp01826f

M3 - Article

AN - SCOPUS:85024132240

VL - 19

SP - 14606

EP - 14614

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 22

ER -