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Updated: Dec 11, 2025
05:07
Assessing the Particulate Matter Removal Abilities of Tree Leaves
Published on: October 7, 2018
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The composition and friction-reducing properties of leaf layers
Michael Watson1, Benjamin White1, Joseph Lanigan1
1Department of Mechanical Engineering, The University of Sheffield, Sheffield, UK.
Proceedings. Mathematical, Physical, and Engineering Sciences
|August 25, 2020
Summary
Autumn leaf litter causes rail network delays due to low friction. This study identifies iron tannate, formed from leaf tannins and rail iron, as the cause of ultra-low friction, enabling better mitigation strategies.
Area of Science:
- Materials Science
- Tribology
- Chemistry
Background:
- Leaf litter on rails causes significant autumn delays and accidents globally.
- Existing hypotheses on leaf-induced low friction lack definitive chemical explanations.
Purpose of the Study:
- To investigate the chemical reaction between sycamore leaves and metallic iron.
- To identify the mechanism behind the ultra-low friction observed in leaf-contaminated rail conditions.
Main Methods:
- Reaction of aqueous sycamore leaf extract with metallic iron.
- Analysis of the precipitate using FTIR, XPS, CHNS, and ICP-MS.
- Tribological testing to measure friction coefficients before and after reaction.
Main Results:
- A black precipitate, identified as iron tannate, was formed.
- Iron tannate is created through the complexation of tannins with dissolved iron ions.
- Friction tests confirmed ultra-low friction with the leaf extract, which significantly increased when tannins were removed.
Conclusions:
- The reaction between leaf tannins and iron generates iron tannate, responsible for extreme friction reduction on rails.
- Understanding this chemical process allows for the development of targeted solutions to mitigate leaf-related rail issues.
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