Tribological Properties and Biotoxicity of Gluconate-Based Ionic Liquids as Glycerol Lubricant Additives

With increasing environmental awareness and a growing emphasis on green practices, water-based lubricants have gained significant traction in the lubrication industry. In this study, we incorporated a synthesized environmentally friendly and biodegradable gluconate ionic liquid (ILs), [OMIm][gluconate], into a glycerol. The tribological properties of [OMIm][gluconate] as a water-based lubricant additive were comprehensively investigated. Compared with glycerol, the results of the study showed that the friction coefficient and wear volume of the dispersions were reduced by 38.9% and 97.2%, respectively. In addition, [OMIm][gluconate] has excellent tribological properties, significant antimicrobial properties, and low toxicity to animals. The excellent tribological properties of [OMIm][gluconate] are attributed to the tribologically active element N in the molecular structure of ILs to the surface of the friction pair during the friction process. At the same time, a physicochemical adsorption process occurs at the interface of the additive molecules with the friction pair and a complex tribochemical took place. This process culminates in the formation of a highly durable tribofilm, contributing to the material's exceptional toughness. Furthermore, the outstanding antimicrobial properties can be attributed to certain lipid-soluble carbon chain structures that disrupt the integrity of bacteria, leading to the effective eradication of Escherichia coli.