Effect of Gemini surfactant structure on water/oil interfacial properties: A dissipative particle dynamics study

Exploring the Performance Advantages of p-Aminobenzenesulfonate-Based Zwitterionic Gemini Surfactants in Oil Recovery

To investigate the specific performance enhancement of oilfield surfactants by using sodium p-aminobenzenesulfonate as a connecting group, cationic surfactant N,N-dimethyl-N-(oxiran-2-ylmethyl)dodecan-1-aminium (DDPA) and zwitterionic gemini surfactant sodium 4-[bis(3-(dodecyldimethylamino)-2-hydroxypropyl)amino]benzenesulfonate (DDBS) were synthesized. The oil recovery performance of these surfactants was compared, revealing that DDBS outperforms DDPA in thermal stability, wettability, adsorption, and resistance to temperature and salinity variations, as well as surface/interface activity, except for emulsification. Core flooding experiments, simulating the conditions of the Xinjiang oilfield, demonstrated that DDBS can achieve the same enhanced oil recovery effect at a concentration that is 1/15 of that of DDPA. Compared with water, DDBS and DDPA can incrementally enhance recovery rates by 7.9% and 8.5%. Furthermore, the synergistic formulation of DDBS with sodium dodecylbenzenesulfonate (SDS) significantly optimized performance, achieving a reduction in interfacial tension to 0.0301 mN m-1. This study provides a research and data foundation for the application of new surfactants in petroleum extraction.

The Effect of Spacer Chain Length on Foam Stability of Mixed Amine Gemini Surfactant/NaOl by Molecular Dynamic Simulations

Foam stability critically determines the efficiency of the mineral flotation process. Although the mixed amine Gemini surfactant/anionic surfactants exhibit excellent flotation performance, atomic-level investigations of the mechanism of their impact on foam stability remain limited. This study employs molecular dynamics simulations to investigate the self-aggregation behavior of mixed amine Gemini surfactant/sodium oleate (NaOl) systems with varying spacer chain lengths at the air/water interface. The structural parameters of self-aggregation, surface tension, synergistic energy, and diffusion coefficient of water molecules were calculated in detail. The results of molecular dynamics simulations indicated that synergistic adsorption between surfactants occurred. Compared with single amine Gemini surfactant systems, the mixed surfactant systems exhibited an enhanced interfacial activity. The spacer chain length significantly affected the adsorption configurations of the mixed surfactant at the air/water interface. For spacer chains containing fewer than five methylene groups, carboxyl groups preferentially adsorbed between two intramolecular amine groups, forming independently clustered aggregates. Conversely, longer spacer chains promoted adsorption between carboxyl groups and intermolecular amine groups, forming interconnected network-like aggregates. Both structural configurations constrained interfacial water mobility, thereby reducing the liquid flow rate between foam films, suppressing water loss and enhancing the mechanical stability of flotation foams.

Comprehensive review of the interfacial behavior of water/oil/surfactant systems using dissipative particle dynamics simulation

A comprehensive understanding of interfacial behavior in water/oil/surfactant systems is critical to evaluating the performance of emulsions in various industries, specifically in the oil and gas industry. To gain fundamental knowledge regarding this interfacial behavior, atomistic methods, e.g., molecular dynamics (MD) simulation, can be employed; however, MD simulation cannot handle phenomena that require more than a million atoms. The coarse-grained mesoscale methods were introduced to resolve this issue. One of the most effective mesoscale coarse-grained approaches for simulating colloidal systems is dissipative particle dynamics (DPD), which bridges the gap between macroscopic time and length scales and molecular-scale simulation. This work reviews the fundamentals of DPD simulation and its progress on colloids and interface systems, especially surfactant/water/oil mixtures. The effects of temperature, salt content, a water/oil ratio, a shear rate, and a type of surfactant on the interfacial behavior in water/oil/surfactant systems using DPD simulation are evaluated. In addition, the obtained results are also investigated through the lens of the chemistry of surfactants and emulsions. The outcome of this comprehensive review demonstrates the importance of DPD simulation in various processes with a focus on the colloidal and interfacial behavior of surfactants at water-oil interfaces.