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 (C₁₀-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 C₁₀-APG and SDS or DATB and the ternary mixtures of C₁₀-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 CO₂ is a promising technique that combines shale gas extraction and CO₂ 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 CH₄ and CO₂ in the kerogen matrix and slit nanopores and explore the displacement efficiency of the residual CH₄ by CO₂ in kerogen slit nanopores. The adsorption energy of CH₄ and CO₂ on the kerogen fragment surface and the isosteric heat of CH₄ and CO₂ in kerogen slit nanopores were examined to demonstrate the competitive adsorption of CO₂ over CH₄ in kerogen slit nanopores, and the different intensity of interactions between the CH₄ and CO₂ molecules with the pore surface plays a key role. An effective displacement process of the residual adsorbed CH₄ by CO₂ in kerogen slit nanopores was performed. The efficiency of displacement was enhanced with the increasing bulk pressure, and the sequestration amount of CO₂ in kerogen slit nanopores increased at the same time. Moreover, it was found that part of CH₄ adsorbed firmly inside the intrinsic pores of the kerogenmatrix was very hard to be displaced by the CO₂ injection. This work demonstrates the microbehaviors of CH₄ and CO₂ in kerogen slit nanopores and the microscopic mechanism of the displacement of CH₄ by CO₂, for the purpose of providing useful guidance for enhancing shale gas extraction by injecting CO₂

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 (N₂, O₂, and CO₂) 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

Additional file 1 of Integrated physiological, metabolomic, and transcriptomic analyses elucidate the regulation mechanisms of lignin synthesis under osmotic stress in alfalfa leaf (Medicago sativa L.)

Supplementary Material