scholarly journals Salt Effects on Formation and Stability of Colloidal Gas Aphrons Produced by Anionic and Zwitterionic Surfactants in Xanthan Gum Solution

2020 ◽  
Vol 4 (1) ◽  
pp. 9
Author(s):  
Behnam Keshavarzi ◽  
Mohsen Mahmoudvand ◽  
Aliyar Javadi ◽  
Alireza Bahramian ◽  
Reinhard Miller ◽  
...  
Keyword(s):  
Surface Tension ◽  
Salt Concentration ◽  
Half Life ◽  
Xanthan Gum ◽  
Sodium Dodecyl ◽  
Life Time ◽  
Dynamic Surface Tension ◽  
Zwitterionic Surfactant ◽  
Dynamic Surface ◽  
Colloidal Gas Aphrons

This work is devoted to the influence of NaCl salt concentration on the formation and stability of colloidal gas aphrons (CGA) produced by the anionic surfactant sodium dodecyl sulfate (SDS) and zwitterionic surfactant coco amido propyl betaine (CAPB) in the presence of xanthan gum (XG) as a stabilizer. Dynamic surface tension measurements as well as volume and half-life time of the produced foams are considered for stability analysis. A sharp decrease of the half-life time and volume of the CGAs at NaCl concentrations larger than 20,000 ppm was observed, which was attributed to the precipitation of SDS in the solution. The mentioned SDS precipitation altered the dynamic surface tension behavior, dilational surface elasticity, and turbidity of the solution. The main reason for the precipitation of SDS is the increased Krafft point caused by the addition of salt. However, for the zwitterionic surfactant CAPB, the effects of added NaCl on the interfacial properties required for CGAs production was negligible due to the simultaneous effects on the cationic and anionic head groups in the CAPB leading to negligible changes in the net repulsion forces. Yet, an overall reduction in the half-life time of CGAs with increasing salt concentration, even when we have no precipitation, was observed for both surfactants, which could be explained by the reduction in the ability of XG to increase the viscosity with increasing salt concentration.

scholarly journals The unusual symmetric reopening effect induced by pulmonary surfactant

2014 ◽  
Vol 116 (6) ◽  
pp. 635-644 ◽  
Author(s):  
Eiichiro Yamaguchi ◽  
Matthew J. Giannetti ◽  
Matthew J. Van Houten ◽  
Omid Forouzan ◽  
Sergey S. Shevkoplyas ◽  
...  
Keyword(s):  
Surface Tension ◽  
Pulmonary Surfactant ◽  
Sodium Dodecyl ◽  
Dynamic Surface Tension ◽  
Dynamic Surface ◽  
Airway Reopening ◽  
Image Velocimetry ◽  
Microparticle Image Velocimetry ◽  
The Stability ◽  
Do So

This study investigates the stability of a finger of air as it propagates into a liquid-filled model of a liquid-filled model of a pulmonary bifurcation. We seek to elucidate the stability characteristics of the reopening of daughter airways, an event that may be important to the treatment of acute lung disease. To do so, we investigated the symmetry of reopening under conditions of nearly constant surface tension with 1) purified H2O or 2) an anionic surfactant (sodium dodecyl sulfate). Dynamic surface tension was investigated using pulmonary surfactant (Infasurf) with and without the presence of albumin. Flow visualization was accomplished using a microparticle image velocimetry (μ-PIV)/shadowgraph system through which we measured 1) the propagation velocity of the finger of air that reopens each daughter branch, and 2) the instantaneous and averaged velocity field of liquid phase surrounding the tip of the propagating bubble. Only pulmonary surfactant demonstrated the ability of maintaining a nearly symmetric propagation in the daughter channels, which is likely to lead to homogeneous airway reopening. In contrast, when pulmonary surfactant was inactivated by albumin or when the system was held at a nearly constant surface tension, reopening occurred asymmetrically. Our analysis suggests that Infasurf's dynamic surface tension qualities are important to stabilize the removal of liquid obstructions. This demonstrates a new important function of pulmonary surfactant for airway reopening of a multibranched network.

scholarly journals A pH-Responsive Foam Formulated with PAA/Gemini 12-2-12 Complexes

2021 ◽  
Vol 5 (3) ◽  
pp. 37
Author(s):  
Hernán Martinelli ◽  
Claudia Domínguez ◽  
Marcos Fernández Leyes ◽  
Sergio Moya ◽  
Hernán Ritacco
Keyword(s):  
Surface Tension ◽  
Dynamic Surface Tension ◽  
Foam Formation ◽  
Ph Responsive ◽  
Dynamic Surface ◽  
X Ray ◽  
Equilibrium Surface Tension ◽  
Potential Applications ◽  
The Stability ◽  
Air Interfaces

In the search for responsive complexes with potential applications in the formulation of smart dispersed systems such as foams, we hypothesized that a pH-responsive system could be formulated with polyacrylic acid (PAA) mixed with a cationic surfactant, Gemini 12-2-12 (G12). We studied PAA-G12 complexes at liquid–air interfaces by equilibrium and dynamic surface tension, surface rheology, and X-ray reflectometry (XRR). We found that complexes adsorb at the interfaces synergistically, lowering the equilibrium surface tension at surfactant concentrations well below the critical micelle concentration (cmc) of the surfactant. We studied the stability of foams formulated with the complexes as a function of pH. The foams respond reversibly to pH changes: at pH 3.5, they are very stable; at pH > 6, the complexes do not form foams at all. The data presented here demonstrate that foam formation and its pH responsiveness are due to interfacial dynamics.

Pool Boiling Heat Transfer in Aqueous Solutions of an Anionic Surfactant

2000 ◽  
Vol 122 (4) ◽  
pp. 708-715 ◽  
Author(s):  
V. M. Wasekar ◽  
R. M. Manglik
Keyword(s):  
Anionic Surfactant ◽  
Pure Water ◽  
Pool Boiling ◽  
Sodium Dodecyl ◽  
Dynamic Surface Tension ◽  
Nucleate Boiling ◽  
Optimum Level ◽  
Lauryl Sulfate ◽  
Dynamic Surface ◽  
Influence Of Temperature On

Saturated nucleate pool boiling of aqueous surfactant solutions on a horizontal cylindrical heater has been experimentally investigated. Sodium dodecyl or lauryl sulfate (SDS or SLS), an anionic surfactant, is employed. Boiling performance, relative to that for pure water, is found to be enhanced significantly by the presence of SDS, with an early onset of nucleate boiling. An optimum level of enhancement is observed in solutions at or near critical micelle concentration of the surfactant; the enhancement, however, decreases considerably in higher concentration solutions. The dynamic surface tension measurements indicate a substantial influence of temperature on the overall adsorption isotherm. The diffusion kinetics of surfactant molecules and micelles is, therefore, expected to be quite different at boiling temperature than at room temperature. This greatly modifies the boiling mechanism that is generally characterized by the formation of smaller-size bubbles with increased departure frequencies, and a decreased tendency to coalesce which causes considerable foaming. [S0022-1481(00)00704-0]

An axisymmetric model for the analysis of dynamic surface tension

RSC Advances ◽  
2015 ◽  
Vol 5 (11) ◽  
pp. 7921-7931 ◽  
Author(s):  
S. I. Arias ◽  
J. R. Fernández ◽  
L. García-Rio ◽  
J. C. Mejuto ◽  
M. C. Muñiz ◽  
...  
Keyword(s):  
Surface Tension ◽  
Diffusion Length ◽  
Dynamic Surface Tension ◽  
Ionic Surfactants ◽  
Adsorption Behaviour ◽  
Dynamic Surface ◽  
Axisymmetric Model

An axisymmetric model accounts for dynamic surface tension of non-ionic surfactants under consideration of diffusive adsorption behaviour with a finite diffusion length.

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