Tunable stability of oil-containing foam systems with different concentrations of SDS and hydrophobic silica nanoparticles

Le²,

et al. 2023

Polymers

The stable maintenance effect of a chemical oil displacement agent on a foam liquid film usually creates problems with the oilfields surface system. To achieve comprehensive insights into the influence mechanism of these chemical agent components on the foam liquid film, an “SDBS/HPAM/OH-” water-based foam simulation system and corresponding control systems were constructed by adjusting the categories and quantities of component molecules by molecular dynamics (MD) simulation. The simulated results indicated that the foam stability follows the order of “SDBS/HPAM/OH−” system > “SDBS/HPAM” system > “SDBS” system. The smaller the inclination angle of the SDBS molecular tail chain, the greater the tendency of the SDBS molecular configuration to be “upright” at the gas−liquid interface, which is not conducive to preventing the aggregation and penetration of gas molecules at the gas−liquid interface. Although the presence of HPAM molecules can significantly enhance the stability of the liquid film by restricting the liquid film’s drainage and the diffusion of gas molecules, the addition of HPAM molecules would weaken the formation ability of the foam liquid film. Through decreasing the aggregation of cations around the co-adsorption layer, OH− not only enhances the interfacial activity of SDBS molecules, but also reduces the electrostatic repulsion between –COO− groups on the HPAM molecular chain, which makes the foam more stable. With an increase in the pH, SDBS concentration, and HPAM concentration, the stability of foam liquid film was strengthened. These results are helpful in facilitating new insights into the formation and stabilization mechanism of water-based foams. In particular, they provide support for the development and application of new defoaming technologies.

Section: Resultsmentioning

confidence: 99%

Molecular Dynamics Simulation of the Synergistic Effect of Alkali/Surfactant/Polymer on the Formation and Stabilization of Water-Based Foam Systems

Le²,

et al. 2023

Polymers

“…When the silica sol content is low, the cell size distribution of the modified foam is uniform and the morphology is good. During the foaming, silica sol plays an important role in cell nucleation, , which can affect the cell size and the cell wall thickness, inducing heterogeneous nucleation with high nucleation efficiency, thereby increasing cell stability. A small amount of silica sol can disperse evenly in the foam to increase the strength of foam.…”

Section: Resultsmentioning

confidence: 99%

Effective Halogen- and Phosphorus-Free Polyphenylene Ether Resin-Based Flame-Retardant Foam

Zhao

2021

ACS Omega

A novel halogen- and phosphorus-free intrinsic flame-retardant foam is fabricated from curable phenol-terminated polyphenylene ether resin with a high molecular weight using phenol, formaldehyde, and diphenyl ether as starting materials. The limiting oxygen index (LOI) of the pure foam is 24.90% ± 0.28. When 0.5 wt % silica sol is added, the LOI of the foam (SPF-0.5) is up to 28.5% ± 0.15 and both the combustion heat release rate and total combustion heat are low. Moreover, the SPF-0.5 foam exhibits high carbon residue, high compressive strength, and low pulverization rate and is superior to some previously reported phenolic foam. The flame-retardant mechanism includes the condensed-phase flame retardation and the gas-phase flame retardation, with the former being the main step, which is based on the high cross-linking density, the higher strength and smaller size of foam cells, and the formation of a carbon–silicon compound in the foam. This halogen- and phosphorous-free flame-retardant foam is also environmentally benign.

“…studied the effects of calcium on foam stability through molecular dynamics simulation by using three surfactants including linear alkyl benzene sulfonate (LAS), sodium dodecyl sulfate (SDS) and seven single lauryl ether glycol (C 12 E 7 ), then found that the foam stability of surfactants was less affected by calcium ions, which was related to the enhanced interaction con gurations. Sun [15] et al studied the stability of the oil-containing SDS stabilized nitrogen foam in water and revealed that the concentration and con guration of SDS could affect its interactions with SiO 2 nanoparticles and with oil molecule.…”

Section: Introductionmentioning

confidence: 99%

Molecular Viewpoint for the Stability Mechanism of SiO2/SDS Dispersion

Liu

Chen

et al. 2022

Preprint

The dispersion of silica dioxide (SiO2)/sodium lauryl sulfate (SDS) have been widely used in the oilfield development and the remaining oil displacement, but its instability is still a problem in the practical engineering application. In this paper, the mechanism of foam stability was investigated by combining the measurement of interfacial energy of nanoparticles at the gas-liquid interface with the dynamics simulation of molecular diffusion. The results showed that the addition of SiO2 nanoparticles improved the interfacial energy and interfacial activity at the gas-liquid interface, meanwhile limited the movement of SDS molecules and water molecules, which was beneficial for the foam stability. Notably, the addition of modified SiO2 nanoparticles further enhanced the interfacial energy at the gas-liquid interface and strengthened the restriction of water/SDS molecular movement, thereby slowing down the drainage and decay of the foam dispersions. The mechanism investigation was of benefit for foam flooding engineering application.