Unraveling Water-Based Lubrication with Carbon Dots of Asphaltene Origin

Abstract

Despite the lower toxicity of water-based lubricants over nonrenewable petroleum-based analogues, they face challenges in achieving widespread adoption due to low stability and inadequate friction-reduction performance. To address this, a cost-effective nanoadditive is synthesized by expansive oxidation of asphaltenes to create biocompatible asphaltene-derived carbon dots [(ACDs); 5 nm]. These ACDs exhibit excellent water redispersibility, promoting long-term friction reduction and marking the first use of an asphaltene-based system for friction reduction in water or oil. Even at low loadings (0.2−4.0 wt %), ACDs significantly reduce friction on steel surfaces (>54%) with tribofilm stability surpassing pristine carbon dots, typical carbonbased graphene quantum dots, and inorganic nanomaterials (commercial 5 and 20 nm silica). The ACDs' attributes include high negative zeta potential, considerable water uptake, varied functional groups, biocompatibility, and a nanodisc shape conducive to stable tribofilm formation through effective particle stacking. The scalable synthesis, high yield, and impressive water redispersibility of ACDs position them favorably for commercial water-based lubrication.

The Asphaltenes: State-of-the-Art Applications and Future Perspectives in Materials Science

“…In another recent report, Akakuru et al prepared biocompatible asphaltene-derived carbon dots (ACDs) having 5 nm size to be utilized as a nanoadditive to reduce friction in water or oil. The low stability and inadequate friction-reduction performance of water-based lubricants motivated Akakuru et al to form ACDs from petroleum-based asphaltenes.…”