Application of analytical ultracentrifugation in gravitational sweep mode coupled with turbidity detection for analyzing polydisperse emulsions of aged biodiesel and alkanes

Julian Türck ^1,2, Kristian Schilling ³, Johannes Walter ⁴

⁰Leuphana Universität Lüneburg Germany julian.tuerck@stud.leuphana.de.

Rsc Advances +

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December 8, 2025

View abstract on PubMed

Summary

This study developed a method to analyze emulsions in aged alternative fuels like biodiesel and hydrogenated vegetable oils (HVO). The technique accurately measured droplet sizes, aiding understanding of fuel aging and engine oil stability.

Area Of Science

Fuel Chemistry and Engineering
Lubricant Tribology
Materials Science

Background

Alternative fuels can reduce greenhouse gas emissions but introduce complex fuel component interactions.
Fuel aging increases component polarity, widening the gap and fostering emulsion formation within fuels and engine oils.
Emulsions in aged fuels pose challenges for engine operation and lubricant performance.

Purpose Of The Study

To develop and validate an analytical method for investigating emulsions in aged biodiesel-alkane systems without water or stabilizers.
To characterize the physical properties of emulsions formed from aged biodiesel, hydrogenated vegetable oils (HVO), and base oil (BO).
To assess the influence of polar molecules on emulsion characteristics.

Main Methods

Utilized analytical ultracentrifugation with multi-wavelength turbidity detection.
Employed gravitational sweep experiments to analyze droplet size distributions.
Investigated systems comprising aged biodiesel, HVO, and BO, with and without polar additives like solketal and 1-octanol.

Main Results

Successfully determined high-resolution droplet size distributions for biodiesel-HVO (500-5500 nm) and biodiesel-BO (400-3750 nm) emulsions.
Observed distinct sedimentation velocities, with HVO systems exhibiting twice the velocity of BO systems.
Quantified the impact of polar molecules on emulsion characteristics via percentile size values.

Conclusions

The developed analytical ultracentrifugation method is effective for analyzing unstable, turbid, and polydisperse emulsion systems.
This methodology provides insights into the physical processes governing fuel aging and its impact on engine oil.
Understanding emulsion formation is crucial for the stability and performance of alternative fuels and lubricants.

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