Nile tilapia industrialization waste: Evaluation of the yield, quality and cost of the biodiesel production process

The biodiesel produced from Nile tilapia waste consists of an alternative material for sustainable energy production, meeting the growing energy demand without damaging the environment, being this fish waste is often disposed in the inadequate form. The aim of this work was to investigate the biodiesel production from fish oil extracted from Nile tilapia processing waste (heads), through a full factorial experimental design. The biodiesel production was carried out by homogeneous alkaline transesterification using ethanol, and potassium hydroxide (KOH) as the catalyst. The best condition of biodiesel production was evaluated as a function of the catalyst concentration, oil:ethanol molar ratio and reaction time, according to the factorial design and the responses were yield, production cost, acid value, and kinematic viscosity. The maximum yield of biodiesel was 92% (w w(-1)), this result was obtained with KOH 2% (w w(-1)), molar ratio of 1:12 (oil: ethanol) and reaction time of 4 h. This condition also ensured a product with lower VA (0.63 mg(KOH) g(-1)), lower kinematic viscosity (2.78 mm(2) s(-1)), and a low cost of biodiesel production (0.17 US$ kg(-1)). TLC and FTIR analyses pointed out that the triglycerides of the fish oil were converted into biodiesel. The fatty acids profiles for the crude oil, bleached oil and biodiesel from Nile tilapia oil were determined by gas chromatography and, they have not presented significant differences in their percentage values. Based on the lipid profile obtained, Nile tilapia oil showed suitable characteristics, being a promising source for biodiesel obtainment. This study showed that bleached oil from Nile tilapia heads stands out as a promising source for producing biodiesel with high yield, positive economic potential, and better physicochemical properties. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Biodiesel production from fish oil extracted from Nile tilapia waste was optimized using homogeneous alkaline transesterification with ethanol and potassium hydroxide as catalyst. The best condition achieved a biodiesel yield of 92% with KOH 2%, oil:ethanol molar ratio of 1:12, and reaction time of 4 hours, resulting in a product with low acid value, low kinematic viscosity, and low production cost. TLC and FTIR analyses confirmed the conversion of triglycerides into biodiesel, and gas chromatography showed no significant differences in fatty acid profiles between crude oil, bleached oil, and biodiesel.