Synthesis and physicochemical properties of estolide ester and amide made from used cooking oil as bio-lubricant

Hoong, Seng Soi and Arniza Mohd Zan and Nik Siti Mariam Nek Mat Din and Noor Armylisas Abu Hassan and Tang Sook Wah and Tuan Noor Maznee Tuan Ismail and Yeong, Shoot Kian (2023) Synthesis and physicochemical properties of estolide ester and amide made from used cooking oil as bio-lubricant. Journal of Oil Palm Research (Malaysia), 35 (4). pp. 725-737. ISSN 2811-4701

Palm-based used cooking oil (UCO) is an inexpensive material that could be used as a bio-lubricant. However, its use as a bio-lubricant is limited by its inferior cold flow and oxidation stability properties. This study shows an approach to make bio-lubricant base oil from UCO that displayed good cold flow and oxidation stability. UCO was saponified and hydrolysed to yield a mixture of fatty acids, which was subsequently reacted with hydrogen peroxide and acetic acid to generate an estolide mixture with hydroxyl and carboxylic acid groups. The hydroxyl groups of the estolide mixture were end-capped with lauric acid, while its carboxylic acid groups were converted to either ester or amide functionality with 2-ethylhexanol and dibutylamine, respectively. Physicochemical properties evaluation revealed that the saturated branched structure of estolide ester and amide contributed to improved pour point (-12°C) and better oxidation stability up to 200oC as compared to UCO. Additionally, the estolide ester and amide exhibited a better viscosity index and pour point than a commercial mineral oil lubricant. The estolide ester can be classified as ISO VG 68 base oil, while the estolide amide displayed a higher viscosity grade (ISO VG 150) due to the presence of dibutylamide moiety.

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Abstract

Palm-based used cooking oil (UCO) is an inexpensive material that could be used as a bio-lubricant. However, its use as a bio-lubricant is limited by its inferior cold flow and oxidation stability properties. This study shows an approach to make bio-lubricant base oil from UCO that displayed good cold flow and oxidation stability. UCO was saponified and hydrolysed to yield a mixture of fatty acids, which was subsequently reacted with hydrogen peroxide and acetic acid to generate an estolide mixture with hydroxyl and carboxylic acid groups. The hydroxyl groups of the estolide mixture were end-capped with lauric acid, while its carboxylic acid groups were converted to either ester or amide functionality with 2-ethylhexanol and dibutylamine, respectively. Physicochemical properties evaluation revealed that the saturated branched structure of estolide ester and amide contributed to improved pour point (-12°C) and better oxidation stability up to 200oC as compared to UCO. Additionally, the estolide ester and amide exhibited a better viscosity index and pour point than a commercial mineral oil lubricant. The estolide ester can be classified as ISO VG 68 base oil, while the estolide amide displayed a higher viscosity grade (ISO VG 150) due to the presence of dibutylamide moiety.

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Item Type:	Article
AGROVOC Term:	palm oils
AGROVOC Term:	cooking oils
AGROVOC Term:	hydrolysis
AGROVOC Term:	research
AGROVOC Term:	chemicophysical properties
AGROVOC Term:	oxidation
AGROVOC Term:	biofuels
AGROVOC Term:	lubricants
Geographical Term:	Malaysia
Uncontrolled Keywords:	esterification, kinematic viscosity, oxidation stability, palm oil, pour point
Depositing User:	Nor Hasnita Abdul Samat
Date Deposited:	29 Apr 2025 01:19
Last Modified:	29 Apr 2025 01:19
URI:	http://webagris.upm.edu.my/id/eprint/1785

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