Surfactant mediated particle aggregation in nonpolar solvents
Mojtaba Farrokhbin1, Biljana Stojimirović2, Marco Galli2
1Department of Inorganic and Analytical Chemistry, University of Geneva, Sciences II, 30 Quai Ernest-Ansermet, 1205 Geneva, Switzerland. gregor.trefalt@unige.ch and Department of Physics, Faculty of Sciences, Yazd University, Yazd 89195-741, Iran.
Physical Chemistry Chemical Physics : PCCP
|August 23, 2019
Summary
Particle aggregation in nonpolar media depends on surfactant concentration. Stability increases with particle charge up to a point, then decreases as particles neutralize. The Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory accurately predicts this behavior.
Area of Science:
- Colloid and Surface Science
- Physical Chemistry
Background:
- Particle aggregation in nonpolar media is a critical phenomenon in various industrial applications.
- Understanding the factors influencing colloidal stability is essential for controlling particle interactions.
Purpose of the Study:
- To investigate the aggregation behavior of particles in nonpolar media as a function of surfactant concentration.
- To determine the relationship between particle surface charge and colloidal stability.
- To quantitatively assess the applicability of the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory.
Main Methods:
- Time-resolved light scattering was employed to monitor particle aggregation.
- Surface charges, screening lengths, and van der Waals forces were experimentally measured.
Main Results:
- Particle suspensions showed instability at low surfactant concentrations due to weak particle charging.
- Increasing surfactant concentration led to higher particle charges and enhanced suspension stability.
- At high surfactant concentrations, particle neutralization resulted in rapid aggregation.
Conclusions:
- The study demonstrates a clear correlation between surfactant concentration, particle surface charge, and colloidal stability.
- The Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory successfully predicted the observed stability ratios.
- Experimental measurements of surface charge, screening length, and van der Waals forces are crucial for accurate DLVO predictions.
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