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Coalescence Behavior of Stable Pendent Drop Pairs Held at Different Electric Potentials
Sameer Mhatre1,2, Tomas Hjartnes1, Sébastien Simon1
1Ugelstad Laboratory, Department of Chemical Engineering , Norwegian University of Science and Technology (NTNU) , NO-7491 Trondheim , Norway.
Langmuir : the ACS Journal of Surfaces and Colloids
|February 4, 2020
Summary
Surface-active molecules like asphaltenes and demulsifiers lower the critical voltage for electrocoalescence in brine-oil drops. These compounds alter electrostatic attraction and coalescence behavior compared to clean drops.
Area of Science:
- Colloid and Surface Science
- Electrochemistry
- Interfacial Phenomena
Background:
- Stable pendent drop pairs in brine-oil systems are crucial in various industrial processes.
- Understanding interfacial stabilization and electrostatic interactions is key to controlling drop behavior.
- Surface-active compounds significantly influence interfacial properties and drop dynamics.
Purpose of the Study:
- To investigate the electrocoalescence behavior of stable pendent drop pairs.
- To compare the effects of asphaltenes and demulsifiers on interfacial stabilization and electrostatic interactions.
- To determine how surface-active molecules influence drop attraction and coalescence under applied electric fields.
Main Methods:
- Experimental study of electrocoalescence using stable pendent drop pairs.
- Systematic variation of electric potential, interdrop separation, and drop size.
- Utilized a solvent mixture to ensure optical clarity for asphaltene-laden drop experiments.
- Comparative analysis of drops stabilized by asphaltenes, demulsifiers, and clean interfaces.
Main Results:
- Surface-active molecules, including asphaltenes and demulsifiers, lower the critical coalescence potential (ΔVcrit).
- The minimum voltage for attraction (ΔVm) and the degree of attraction differ between clean and stabilized drops.
- Demulsifier-laden drops showed distinct attraction, coalescence, and noncoalescence behaviors compared to asphaltene-stabilized drops.
- Asphaltenes and demulsifiers differentially affect drop response to electric potential.
Conclusions:
- Asphaltenes and demulsifiers significantly modify the electrocoalescence behavior of brine-oil drops.
- The observed differences in coalescence are attributed to the complex interplay of hydrodynamics, electrostatics, and interfacial molecular reorganization.
- Surface-active compounds play a critical role in controlling electrostatic drop-drop interactions and coalescence.
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