As you might already know I did my internship at the Olivine Industries Company in Harare. The company specializes in production of fat based products - Cooking Oil, Margarine and Spreads, Soaps, candles (Wax based) you name them. It has 2 processing facilities - the WillowVale Factory (Southerton, Harare) and the Birmingham road factory. The main raw materials for extraction of oils are Soya Beans and Cotton Seeds. The process involves crushing the beans (or seeds) and extracting the oil using an alcohol called Hexane. Of course its pretty much more complicated but that forms the gist of it! However this extraction process yields a by-product referred to as soap stock.
Soap stock is predominantly fats and oils and water (with a whole lot of other mineral components). It forms from fat and oil spillages and unrecoverable oils. Its composition is not fixed and varies from facility to facility - day to day even. Soap stock contains too many oils and fats to discard into the environment and is not discarded as is due to the problems associated with fats in water bodies - e.g. increased B.O.D. (a measure of oxygen consumed by bacteria that "feed" on the fats), clogging of pipe works (go through your sink after washing fat laden dishes to appreciate this phenomenon - now imagine it on an industrial scale!) and decreased dissolved oxygen in aquatic bodies. The effects are rather obvious - decreased aquatic life and loss of biodiversity. Soap stock is therefore sent through a process referred to as acidulation which includes addition of concentrated acid and boiling to hydrolyze the fats and then mechanical separation (fat - water separation on steroids!). The fatty layer is now referred to as Acid oil and if your raw material is soya beans - its now called Soya Acid Oil.
Soya Acid Oil is highly oxygenated and contains a greater component of free fatty acids - (Its not really the best raw material for a lot of processes - in less geeky talk!). It can be used in soap formulations but its color dulls soaps and creates an unfavorable soap colour. Some window putty formulations use it as well but not many of the uses for acid oil fail to equate the product value to the cost of its production. My research was therefore to use the fatty acid component of acid oil to manufacture Bio-Diesel via a reaction scheme called esterification. The residual triglyceride component would also be trans-esterified into Bio-diesel as well. Esterification converts the fatty acid component to esters by reacting with an alcohol (Ethanol) in the presence of a mineral catalyzing acid (sulphuric acid). The trans-esterification reaction uses the smaller remaining triglyceride component and converts it to ethyl esters as well via a reaction mechanism loosely similar to the esterification reaction scheme. The Bio-diesel produced would then be used in any diesel engines that any vegetable processing facility that produces vegetable oils (and acid oil/soapstock) has. The research was therefore to obtain the best possible operating parameters for acid oil conversion into biodiesel. The Taguchi Design of Experiment was employed to identify these parameter levels.
Bio-diesel produced this way does not put any strain on agri-produce as is the case with most sources of bio derived diesel (and fuels really!). Besides dealing with a product that the companies already have problems deriving value out of, it also reduces the fuel load on the parent company. Bio diesel also has significantly lesser environmental impacts and performs better than petro derived fuels. The conversion kinetics where extremely favorable and indicated a potential for diesel to be derived out of this waste product by companies that operate within the vegetable oil processing industries.
I have included a clip of my presentation to the adjudicating panel on YouTube. Please feel free to check the video out and use it for any of your research purposes. Also comment in the section below - with anything else you have to say. Your contribution is much appreciated!