Chemical Review and Letters

Conversion of used engine oils from agricultural machinery into colloidal graphite greases enhanced lubricating greases

Document Type : Research Article

Authors

Saja Nafea Mohsen 1
A. V. Rukhov 2

1 College of Engineering, The Iraqia University, Baghdad, Iraq.

2 Tambov State Technical University, Tambov, Russia.

https://doi.org/10.22034/crl.2025.532873.1650
Abstract
The article examines the development of a stable lubricant enhanced with colloidal graphite, utilizing recycled 15W40 diesel engine oil thickened with calcium soap. The study reveals that increasing the graphite concentration results in a gradual rise in water content, while the amount of thickener remains unchanged. Furthermore, higher graphite levels lead to a reduction in penetration values, decreasing from 440 units to 310 units. This suggests an improvement in grease consistency and stiffness. The dropping point also shows notable changes, increasing from 79°C to 88°C at a graphite concentration of 150 ppm, before declining to 81°C with further graphite additions. Regarding anti-wear performance, the smallest wear scar diameter is observed at the same 150 ppm concentration, measuring 0.215 mm—25.1% smaller than that of the control sample.

Graphical Abstract

Conversion of used engine oils from agricultural machinery into colloidal graphite greases enhanced lubricating greases

Keywords

Processing of agricultural waste
Colloidal graphite
Nanographite
Consistent lubricants
Electrochemical exfoliation

Subjects

Chemical Review and Letters
Volume 9, Issue 2 - Serial Number 2
March and April 2026
Pages 351-357

  • Receive Date 07 June 2025
  • Revise Date 24 July 2025
  • Accept Date 07 August 2025

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