Statistical Optimization of Biodiesel Production from Salmon Oil via Enzymatic Transesterification: Investigation of the Effects of Various Operational Parameters

Vegneshwaran V Ramakrishnan,Yi Liu,Wade Murphy,Deepika Dave,Winny Routray

doi:10.3390/pr9040700

Vegneshwaran V Ramakrishnan, Yi Liu + Show 3 more

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https://doi.org/10.3390/pr9040700

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Abstract

The enzymatic transesterification of Atlantic salmon (Salmo salar) oil was carried out using Novozym 435 (immobilized lipase from Candida antartica) to produce biodiesel. A response surface modelling design was performed to investigate the relationship between biodiesel yield and several critical factors, including enzyme concentration (5, 10, or 15%), temperature (40, 45, or 50 °C), oil/alcohol molar ratio (1:3, 1:4, or 1:5) and time (8, 16, or 24 h). The results indicated that the effects of all the factors were statistically significant at p-values of 0.000 for biodiesel production. The optimum parameters for biodiesel production were determined as 10% enzyme concentration, 45 °C, 16 h, and 1:4 oil/alcohol molar ratio, leading to a biodiesel yield of 87.23%. The step-wise addition of methanol during the enzymatic transesterification further increased the biodiesel yield to 94.5%. This is the first study that focused on Atlantic salmon oil-derived biodiesel production, which creates a paradigm for valorization of Atlantic salmon by-products that would also reduce the consumption and demand of plant oils derived from crops and vegetables.

Highlights

IntroductionBiodiesel is a processed fuel that is produced via transesterification of triglycerides derived from naturally occurring plant oils and animal fats
The aim of this work was to maximize the biodiesel production from the salmon oil, which can be developed as an effective way to valorize the large amounts of Atlantic salmon by-products
The highest yield of 91.86% was obtained from the 16 h reaction at 45 ◦ C with 15% enzyme concentration and 1:4 oil/alcohol molar ratio (Run order 41)

Summary

Introduction

Biodiesel is a processed fuel that is produced via transesterification of triglycerides derived from naturally occurring plant oils and animal fats. The triglycerides are converted into fatty acid methyl esters, with glycerol produced as a by-product. Three methods have been traditionally used to produce biodiesel, including acid catalysis, base catalysis, and non-catalytic transesterification using supercritical alcohol [4]. The most commonly used commercial process for biodiesel production is alkali-catalyzed transesterification using sodium hydroxide or potassium hydroxide due to their relatively low cost and high conversion efficiency [3]. Chemical transesterification has multiple disadvantages [5], such as the high dependency of conversion efficiency on the content of water and free fatty acids in the raw materials and the tremendous energy consumption due to the high reaction temperature and product separation process. The acid or base catalysts are not reusable, and extra steps of neutralization are required to dispose of them as an aqueous salt waste stream, which is less environmentally hazardous [6]

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