Effectiveness of Enzymatic Transesterification of Beeftallow Using Experimental Enzyme Ns88001 with Methanol and Hexane

Abstract

The high demand for fossil fuels and their limited supply have prompted the search for alternative renewable fuels such as biodiesel, bioethanol and biogas from biomass materials [1,2]. Biodiesel is a renewable fuel that can be used in compression-ignition engines instead of petroleum diesel [3,4]. It has several qualities over diesel including: being sulfur free, non-toxic, biodegradable and non-carcinogenic [5]. These characteristics make it more greener and eco-friendly than diesel [6-10]. There are many raw materials that can be used as a feedstock for the production of biodiesel including: plant oils, animal fats, microbial mass and waste materials [7]. The most popular plants used as a feedstock are jatropha, canola, coconut, cottonseed, groundnut, karanj, olive, palm, peanut, rapeseed, safflower, soybean and sunflower [3,7,10]. The most popular animal sources used as a feedstock are beef tallow, chicken fat, lamb fat, lard, yellow grease and hemp oil [3,11-13]. The waste materials include: waste cooking oil, greasy by-product from omega-3 fatty acid production and fish waste [7,10]. The main component of fats and oils are triacylglycerols (triglycerides) which are made of different types of fatty acids with one glycerol (glycerine) being the backbone. The types of fatty acids present in the triglycerides determine the fatty acids profile. Fatty acid profiles from plants and animal sources are different and each fatty acid has its own chemical and physical properties which can be a major factor influencing the properties of biodiesel [7,14]. Transesterification is a classic chemical process used to convert the vegetable oils and animal fats to biodiesel. Usually, a short chain alcohol is used with the feedstock to convert methyl esters and glycerin. The objective is to reduce the viscosity of oil by turning it into biodiesel [15]. Transesterification can proceed with one of three catalysts: acid, alkali and enzyme. With an acid catalyst, the proton is donated to the carbonyl group which makes it more reactive. A base catalyst is used to remove the proton from alcohol which makes the reactants more reactive. Both acid and alkali methods require more energy and a downstream processing step is required for removing the by-product (glycerin) [16]. An enzymatic catalyst cleaves the backbone of the glycerol which makes the reactants more reactive, giving the product without the need for a downstream processing step. The glycerol can be extracted easily and the energy required for the process is minimal. Objectives The main aim of present study was to optimize the enzymatic transesterification process for the production of biodiesel from