In-Situ Synthesis and Characterization of Biodegradable Estolides via Epoxidation from Canola Biodiesel

Abstract

Research on the formulation of estolides from plant seed oils has attracted substantial attention due to their favorable low-temperature properties and environmentally friendly nature. The present research investigates the formulation of canola biodiesel derived estolides for low-temperature applications. The dual-step research method includes ring opening of epoxidized canola biodiesel in the presence of oleic acid, followed by esterification with oleic acid to produce estolides using a mesoporous aluminosilicates possessing Modernite Framework Inverted (MFI) type pentasil structure as a heterogeneous acidic catalyst. Prepared catalyst was characterized to measure the properties essential for the effective catalysis. The catalyst demonstrated promising activity for the estolides formation, >95% conversion was achieved at 110 °C for 6 h using 15 wt % of catalyst loading. 1H NMR technique and oxirane oxygen titrimetric analysis were employed to determine product purity. Physicochemical properties of the reaction products were determined by standard methods and characterization results revealed that the formulated estolides had improved low-temperature, lubricity and rheological properties, and thermo-oxidative stability. Also, biodegradability of the estolides was found to be 92% within 28 days as per the bio-kinetic model. Wear scar diameter of 106 µm was noticed for 10% of alkoxide blend with standard diesel fuel. Overall, outcomes of the physicochemical characterization data indicated that the prepared estolides can act as possible alternative bio-lubricant basestock for various low-temperature applications.

Synthesis of environment‐friendly, sustainable, and nontoxic bio‐lubricants: A critical review of advances and a path forward

“…As castor oil (ricinoleic acid) contains both unsaturation as well as hydroxy groups, it is most commonly studied for estolide synthesis. The ricinoleic acid estolides have better properties than the NPG and TMP esters 93 . The total acidity of ricinoleic acid is decreased with the reaction time, which is expected owing to the esterification of the carboxyl groups during the estolide formation process.…”

“…However, the final acid value is still somewhat higher than recommended, owing to the free acid that the estolides contain. Strategies to reduce this acidity level are under study by the research group 92,93 . Borugadda et al .…”

“…performed enzyme‐catalyzed hydrolysis of castor oil and subsequent esterification of the free ricinoleic acid with a hydroxy group of other ricinoleic acids. Out of lyophilized C. rugosa , immobilized R. miehei and C. antarctica , C. rugosa lipase was found to be the best 92,93 . The reactions were carried out at ~40°C for a very long time of 96 h. Borugadda et al .…”

Synthesis and Physicochemical Properties of New Estolide Esters as Potential Biolubricant Base Oil

“…Biolubricants have been made from plant oils and animal fats such as palm oil, soyabean oil, rapeseed oil and tallow, which are sustainable and renewable resources. Plant oil-based biolubricants are known to be environmental-friendly because of their excellent biodegradability as compared to petrochemical-based lubricants (Parveez et al, 2020;Borugadda and Dalai, 2018;Battersby et al, 1992). Additionally, they also offer other beneficial properties such as low volatility, high flash point and high viscosity indices (Sammaiah et al, 2016;Santos et al, 2004).…”

Fatty Acid Estolides: A Review

“…Yields catalyzed by montmorillonite clay, montmorillonite clay treated by Fe 3+ , and montmorillonite clay treated with cationic surfactants were as follows: 21.0%, 27.0%, and 30.0%, respectively. Borugadda and Dalai () reported the synthesis of estolides from epoxidized canola biodiesel and oleic acid using mesoporous aluminosilicates with the Modernite Framework Inverted‐type pentasil structure. These heterogeneous acidic catalysts, at 15.0 wt% of loading, 6 hours of reaction time, and 110 °C of reaction temperature, result in >95.0% conversion of reactant.…”