Current Status and Future Prospects of Biolubricants: Properties and Applications

Abstract

Biolubricants generated from biomass and other wastes can reduce the carbon footprint of manufacturing processes and power generation. In this paper, the properties and uses of biolubricants have been compared thoroughly with conventional mineral-based lubricants. The biolubricants, which are currently based on vegetable oils, are discussed in terms of their physicochemical and thermophysical properties, stability, and biodegradability. This mini-review points out the main features of the existing biolubricants, and puts forward the case of using sustainable biolubricants, which can be generated from agro-residues via thermochemical processes. The properties, applications, and limitations of non-edible oils and waste-derived oils, such as bio-oil from pyrolysis and bio-crude from hydrothermal liquefaction, are discussed in the context of biolubricants. While the existing studies on biolubricants have mostly focused on the use of vegetable oils and some non-edible oils, there is a need to shift to waste-derived oils, which is highlighted in this paper. This perspective compares the key properties of conventional oils with different oils derived from renewable resources and wastes. In the authors’ opinion, the use of waste-derived oils is a potential future option to address the problem of the waste management and supply of biolubricant for various applications including machining, milling applications, biological applications, engine oils, and compressor oils. In order to achieve this, significant research needs to be conducted to evaluate salient properties such as viscosity, flash point, biodegradability, thermo-oxidative and storage stability of the oils, technoeconomics, and sustainability, which are highlighted in this review.

A Review on Bio-Lubricants as an Alternative Green Product:Tribological Performance, Mechanism, Challenges and Future Opportunities

“…Depending on whether they are made of synthetic or mineral oil, the base oils are divided into five classes (I-V) by the American Petroleum Institute (API) [38,39]. The categorization is also influenced by the oils' sulfur content and hydrocarbon composition, thus makes bio-lubricant promising in lubricant formulation [2,40].…”

“…Biomass base oil stocks [4,14] Synthetic oil base stocks [39,40] Mineral base oil stocks [14,37,40] Re-refined base oil stocks [14,41 1 Categories and sources of various base stocks for formulation of lubricant oils Fig. 1 Sustainability characteristics of bio-lubricant prevalent polyphenolic substance in nature, lignin is found in biomass derived from land.…”

A Review on the Effect of Metal Oxide Nanoparticles on Tribological Properties of Biolubricants

“…Also, it should possess a higher Viscosity Index so the lubricant will affect less with variation of temperature. Besides this, a lubricant also must possess a low freezing point and high boiling point, and it should be capable of resisting the oxidation process . Tribological performance is usually associated with lubricity.…”

“…Besides this, a lubricant also must possess a low freezing point and high boiling point, and it should be capable of resisting the oxidation process. 17 Tribological performance is usually associated with lubricity. Lubricity is the formation of a layer of lubricant on the contacting sliding surface.…”

Cold-Flow Properties of Estolides: The Older (D97 and D2500) versus the Mini-(D5773 and D5949) Methods

“…The development of bio-based lubricants is under active research (Scopus returned >250 articles when searching for ((bio-based or bio-based or soybean or palm or corn or cooking) and lubricant) in 2023 vs. 126 in 2013). We excluded the term "biolubricants", often used with a similar meaning to "bio-based lubricants" [4][5][6][7]. The "biolubricant" term can be confusing, since it is used to describe lubricants in biological systems [8] or environmentally acceptable lubricants (EAL) [9] both of which may be totally petroleumbased.…”