4 research outputs found
Study of the molecular array behaviours and interfacial activities of green surfactant alkyl polyglycoside and the mixed systems with other surfactants on oil–water interface
<p>The widely performance of surfactants is closely related to their interfacial activity, which is essentially determined by the molecular array behaviours at the interface, of which the studies are significance for clearly understanding their structure-performance relationships. In this paper, the detailed molecular array behaviours of green surfactant alkyl polyglycoside (APG) and the mixed systems with other types of surfactants on oil/water interface have been studied using molecular dynamics simulations, and the key theoretical principle was confirmed by quantum chemistry calculations. It was found that the hydrophilic maltose ring head groups of decyl polyglycoside (C<sub>10</sub>-APG) are prone to lie flatly at the oil–water interface, the steric hindrance results in the low interfacial density, which critically determines the limit of the interfacial activity. The interfacial adsorption behaviours of the binary mixtures of C<sub>10</sub>-APG and SDS or DATB and the ternary mixtures of C<sub>10</sub>-APG, SDS and DATB were studied in detail, how the efficient synergism effect could be achieved for the mixture to get super high interfacial activity was discussed. This study provides a strategy to reveal how the molecular interfacial behaviours determine the key interfacial characteristics of the novel surfactants, which might provide help to promote their applications.</p
Molecular Insights into the Enhanced Shale Gas Recovery by Carbon Dioxide in Kerogen Slit Nanopores
Full exploitation
and utilization of the unconventional reservoirs
of shale gas have become a central issue due to the increasing worldwide
energy demand. Enhancing shale gas recovery by injecting CO<sub>2</sub> is a promising technique that combines shale gas extraction and
CO<sub>2</sub> capture and storage (CCS) perfectly. In this study,
a kerogen-based slit-shaped pore with a width of ∼21 Å
was constructed by two kerogen matrices, and the grand canonical Monte
Carlo (GCMC) and molecular dynamics (MD) simulation methods were used
to investigate the adsorption and diffusion properties of CH<sub>4</sub> and CO<sub>2</sub> in the kerogen matrix and slit nanopores and
explore the displacement efficiency of the residual CH<sub>4</sub> by CO<sub>2</sub> in kerogen slit nanopores. The adsorption energy
of CH<sub>4</sub> and CO<sub>2</sub> on the kerogen fragment surface
and the isosteric heat of CH<sub>4</sub> and CO<sub>2</sub> in kerogen
slit nanopores were examined to demonstrate the competitive adsorption
of CO<sub>2</sub> over CH<sub>4</sub> in kerogen slit nanopores, and
the different intensity of interactions between the CH<sub>4</sub> and CO<sub>2</sub> molecules with the pore surface plays a key role.
An effective displacement process of the residual adsorbed CH<sub>4</sub> by CO<sub>2</sub> in kerogen slit nanopores was performed.
The efficiency of displacement was enhanced with the increasing bulk
pressure, and the sequestration amount of CO<sub>2</sub> in kerogen
slit nanopores increased at the same time. Moreover, it was found
that part of CH<sub>4</sub> adsorbed firmly inside the intrinsic pores
of the kerogenmatrix was very hard to be displaced by the CO<sub>2</sub> injection. This work demonstrates the microbehaviors of CH<sub>4</sub> and CO<sub>2</sub> in kerogen slit nanopores and the microscopic
mechanism of the displacement of CH<sub>4</sub> by CO<sub>2</sub>,
for the purpose of providing useful guidance for enhancing shale gas
extraction by injecting CO<sub>2</sub>
Understanding about How Different Foaming Gases Effect the Interfacial Array Behaviors of Surfactants and the Foam Properties
In
this paper, the detailed behaviors of all the molecules, especially
the interfacial array behaviors of surfactants and diffusion behaviors
of gas molecules, in foam systems with different gases (N<sub>2</sub>, O<sub>2</sub>, and CO<sub>2</sub>) being used as foaming agents
were investigated by combining molecular dynamics simulation and experimental
approaches for the purpose of interpreting how the molecular behaviors
effect the properties of the foam and find out the key factors which
fundamentally determine the foam stability. Sodium dodecyl sulfate
SDS was used as the foam stabilizer. The foam decay and the drainage
process were determined by Foamscan. A texture analyzer (TA) was utilized
to measure the stiffness and viscoelasticity of the foam films. The
experimental results agreed very well with the simulation results
by which how the different gas components affect the interfacial behaviors
of surfactant molecules and thereby bring influence on foam properties
was described