Surfactant—electrolyte interactions in concentrated water-in-oil emulsions: FT-IR spectroscopic and low-temperature differential scanning calorimetric studies

Chemical Engineering Communications

Haldenwang

2010

The problem of droplet size dependence on rheological properties of highly concentrated emulsions was studied. Changes in droplet size distribution were achieved by multi-pass flow through a small orifice set as the outlet of a piston-chamber pumping instrument, and extended elongation of droplets combined with the transienttransition flow regime (laminar=turbulent) at the outlet of the orifice provided the shift of the droplet sizes to the smaller-size side of the distribution. Their distributions were wider and of the logarithmic-normal distribution type. Two models were proposed and used to fit the refinement evolution and the width of distributions respectively. The droplet size versus number of pumping cycles was expressed by the fitting parameters, h D , h x , D crit. , x crit. , and C, which, in turn, gave a clear estimation of factors that influence refinement during pumping. These factors involved surfactant type and surfactant concentration, where higher surfactant concentration induced higher efficiency with regard to droplet disruption. The most important part of the result of the investigation is, however, the experimental proof that the shear modulus versus droplet size is not necessarily expressed by a linear reciprocal dependence, but by an exponent equal to 2. It was shown that the stability of highly concentrated emulsions in shearing is determined by some critical value of deformation with reference to the yielding conditions. This value on average equalled 0.07 for all samples under investigation.

Section: Dependence Of Elastic Properties On Droplet Size (Ds)mentioning

confidence: 97%

Highly Concentrated Emulsions: Role of Droplet Size

Yakhoub

Chemical Engineering Communications

Haldenwang

2010

“…From the publication [11] it is known that a surfactant interacts with the AN that is reflected in the changes in the NH peak in IR spectrum. Based on the arguments set out in the literature, the following proposed interactions can take place between the PIBSA-based surfactant head group and AN solution: hydrogen bonds formation, [11,12,16] electrostatic interaction [11] or ion attraction and salt formation. [4] These types of interactions could result in the weakening of the NH bond in the AN molecule that can be seen by the IR spectroscopy.…”

Section: Ftir Analysismentioning

confidence: 99%

“…The IR-spectroscopy has been widely used to study the interactions between ions in solution, [9] polymer and surfactant interactions, [10] and interactions between electrolyte and surfactant in emulsions. [11] While only a few FTIR investigations of the emulsion system stabilized by succinic surfactants are known to have been conducted, the effect of electrolyte concentration on surfactant monolayer was examined. [11,12] These studies revealed the interaction between PIBSA-based surfactants and ammonium nitrate solution.…”

Section: Introductionmentioning

confidence: 99%

“…[11] While only a few FTIR investigations of the emulsion system stabilized by succinic surfactants are known to have been conducted, the effect of electrolyte concentration on surfactant monolayer was examined. [11,12] These studies revealed the interaction between PIBSA-based surfactants and ammonium nitrate solution. The importance of these interactions for interface stability was mentioned in several other publications.…”

Section: Introductionmentioning

confidence: 99%

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IR Studies of Interfacial Interaction of the Succinic Surfactants with Different Head Groups in Highly Concentrated W/O Emulsions

Journal of Dispersion Science and Technology

Kovalchuk

Malkin

2011

The interfacial properties of three succinic surfactants (PIBSA) with different hydrophilic end groups and sorbitan monooleate (SMO) in water-in-oil emulsions of the liquid explosive type were studied. The aqueous phase contained 40% of ammonium nitrate (AN). The trend in equilibrium interfacial tension was found to be PIBSA-MEA > PIBSA-UREA > PIBSA-MEA/ SMO mixture > PIBSA-IMIDE > SMO, where MEA, UREA, IMIDE are amid/amide, urethane and imide end groups, respectively. The same trend was observed for the interfacial elastic modulus. The FTIR study revealed interactions between surfactant head groups and an AN solution. The interactions depend on the polarity of head groups determined by their chemical structure. The packing efficiency of the surfactants under study is also influenced by the chemical structure of head groups. Attempts to model the conformation of the surfactants at the interface were made. The investigation of mixed interfacial cover (PIBSA-MEA/SMO) showed that SMO remained at the interface reducing the interfacial tension at the W/O interface. It was also demonstrated that variation of the nature of head groups influences the rheological properties of emulsions. Bulk elasticity and yielding correlate with interfacial interaction characteristics.

“…This is due to their dual chemical nature namely the existence of hydrophilic and hydrophobic domains in one molecule [1,2]. It is known that the surfactant structure influences the interfacial [3][4][5][6] and bulk properties [3,4] of a system and has an effect on emulsion stability [1,3,[7][8][9]. Therefore, investigation of molecular properties of surfactant structure is an important aspect in understanding the factors that influence emulsion stability.…”

Section: Introductionmentioning

confidence: 99%

A Computational Study of the Succinimide Derivative Surfactant

Kovalchuk

Landman

Journal of Dispersion Science and Technology

2013

Density functional theory (DFT) of calculations was used to optimize the molecular structures of a succinimide surfactant at B3LYP/6-311 level. The interaction of the surfactant with water molecules was investigated. The hydration shell was formed in the form of Hbonds between the hydrophilic group on the surfactant and water molecules. The binding energy of the system increases due to hydrogen bond formation with the water molecules.