Viscoelastic Properties of Produced Water Emulsions
Alireza Zahedi1, Saeed Azizi1, Mark Krzmarzick2
1School of Chemical Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, United States.
Energy & Fuels : an American Chemical Society Journal
|July 8, 2026
Summary
Synthetic produced water (PW) significantly alters sodium dodecyl sulfate (SDS) surfactant behavior at oil-water interfaces, improving oil-water separation by modifying interfacial rheology and emulsion stability.
Area of Science:
- Colloid and Surface Science
- Interfacial Phenomena
- Emulsion Science
Background:
- Understanding fluid interface viscoelasticity is crucial for effective oil-water separation.
- Synthetic produced water (PW) composition can influence surfactant performance in separation processes.
Purpose of the Study:
- To investigate the impact of synthetic produced water (PW) chemistry on interfacial tension and dilatational viscoelasticity of cyclohexane-water interfaces with sodium dodecyl sulfate (SDS).
- To analyze the effect of SDS concentration on emulsion stability and droplet behavior in PW systems.
Main Methods:
- Pendant drop tensiometry and oscillatory dilatational rheology were used to measure interfacial properties.
- SDS concentrations ranged from 0.001-1 g/L at frequencies of 0.1-0.5 Hz.
- Time-resolved droplet size distributions were analyzed for oil-in-PW emulsions.
Main Results:
- PW systems showed lower interfacial tension and a significantly lower apparent critical micelle concentration (CMC) for SDS compared to DI water systems.
- Interfacial dilatational measurements revealed a higher complex modulus and a faster transition to viscous-dominated behavior in PW.
- Increased SDS concentration in PW led to smaller initial droplets and reduced droplet growth, indicating enhanced coalescence reduction.
Conclusions:
- PW chemistry fundamentally alters SDS adsorption, CMC, and interfacial rheology.
- The findings provide critical insights into how water composition influences surfactant-driven interfacial behavior for oil-water separation and PW treatment.
- Enhanced interfacial viscoelasticity in PW systems contributes to improved emulsion stability and separation efficiency.
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