The conversion of linoleic acid into hydroxytetrahydrofuran-structured bio-lubricant

Upstream and Downstream Bioprocessing in Enzyme Technology

The development of biotransformation must integrate upstream and downstream processes. Upstream bioprocessing will influence downstream bioprocessing. It is essential to consider this because downstream processes can constitute the highest cost in bioprocessing. This review comprehensively overviews the most critical aspects of upstream and downstream bioprocessing in enzymatic biocatalysis. The main upstream processes discussed are enzyme production, enzyme immobilization methodologies, solvent selection, and statistical optimization methodologies. The main downstream processes reviewed in this work are biocatalyst recovery and product separation and purification. The correct selection and combination of upstream and downstream methodologies will allow the development of a sustainable and highly productive system.

Biocatalytic production of biolubricants: Strategies, problems and future trends

The increasing worries by the inadequate use of energy and the preservation of nature are promoting an increasing interest in the production of biolubricants. After discussing the necessity of producing biolubricants, this review focuses on the production of these interesting molecules through the use of lipases, discussing the different possibilities (esterification of free fatty acids, hydroesterification or transesterification of oils and fats, transesterification of biodiesel with more adequate alcohols, estolides production, modification of fatty acids). The utilization of discarded substrates has special interest due to the double positive ecological impact (e.g., oil distillated, overused oils). Pros and cons of all these possibilities, together with general considerations to optimize the different processes will be outlined. Some possibilities to overcome some of the problems detected in the production of these interesting compounds will be also discussed.

A bibliometric analysis on the tribological and physicochemical properties of vegetable oil-based bio-lubricants (2010-2021)

Vegetable oil-based bio-lubricants possess potential as an alternative to mineral oil-based lubricants due to their biodegradability and renewability. However, a detailed examination of the publication focus, trend, and future direction related to these bio-lubricants' tribological and physicochemical properties is scarce. Therefore, the study presents a bibliometric analysis of vegetable oil-based bio-lubricant. One hundred sixty-five publications were extracted from Web of Science (WoS) from 2010 to 2021. During this period, the total citation was 2,240, recording an average citation per publication of 13.58. Proceedings of The Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology was the top productive journal, publishing 10.3% of the publications selected on the studied topic. From 2010 to 2021, India was the most productive country working on bio-lubricants due to its abundance of coconut products, followed by Malaysia due to its abundance of palm products. The keyword analysis indicated that a significant amount of work emphasised the derivation of bio-lubricants with an increasing shift towards tribological performance characterisation. From the analysis, palm is the most studied bio-lubricant, followed by castor oil. The reported viscosity and viscosity index values cover an extensive range, allowing these bio-lubricants to be adopted for a wide range of applications. For different vegetable oil-based bio-lubricants, the coefficient of friction is reported from 0.001 to 0.78, with the wear scar diameter being reported from 0.075 μm to 4.59 mm. Even though these bio-lubricants' friction and wear performances can be tabulated, the dataset is still unreliable for lubricant-selection purposes because of the varying test conditions. Such a scenario also limits the ability to correlate the role of fatty acid composition in the vegetable oil-based bio-lubricants in fulfilling their various application-specific potentials. Therefore, this study recommends that a unified correlation between the fatty acid composition and its tribological performance be attained consistently to better elucidate the potential of vegetable oil-based bio-lubricants.