Functional groups of bio-lubricants from crude catfish oil (Pangasius hypothalamus)

Abstract

Bio-lubricants have great potential in the production of lubricating in the future. Several studies have developed animal oils as lubricants, which come from a by-product of fish processing. Fish oil extracted from the material and processed into bio-lubricants reached the highest yield of 94%. This research aimed to study the bio-lubricants functional groups. The research steps extracted crude fish oil as raw material, hydrolysis using HCl catalyst, polymerization using benzoyl peroxide, and polyesterification using ethylene glycol. The extraction process used the wet rendering method with a ratio of catfish waste (viscera) to the water of 1:2 (w/v) at 70 °C for 30 minutes. The best bio-lubricants were analyzed for functional groups using an FT-IR instrument with a wave range of 4000-450 cm−1. The results obtained were the absorption wavelength peak of 3472 cm−1, indicating O-H bonds with the sloping peak and the weak bond. The absorption wave peak of 3006-2852 cm−1 indicated a strong C-H bond (alkane). The absorption wave peaks of 1743 cm−1 indicated the presence of a C=O double bond. The adsorption wave peaks at 1465 cm−1 indicated carbon chain bonds between C-C, while the absorption wave peaks at 1115 and 1174 cm−1 indicated C-O bonds. The three spectral indicated that the ester groups formed in bio-lubricants. In the polymerization reaction, there was no absorption wave of 1600-1500 cm−1 which indicated that all C=C groups had been polymerized by benzoyl peroxide. Meanwhile, a sloping absorption wave of 3472 cm−1 was found in the polyesterification reaction due to the weak O-H bond. The analysis obtained above showed the differences in wave peak between bio-lubricant and crude fish oil as raw material but had the same group shape.