The feedstocks used in the experiment were beef fat supplied by Lucky Frozen Sdn Bhd., chicken fat supplied by Jimat Jaya Sdn Bhd and used cooking oil supplied by Restaurant Mastiara Sdn Bhd. Fats were melted by slowly heating up to 100 C (under reduced pressure to avoid any degradation) to remove the waxy, and other suspended and residual matters. Melted fats were then filtered, centrifuged and decanted. The processed chicken and beef fats were stored in air tight opaque plastic jars to prevent oxidation. UCO retrieved from the restaurant were filtered and poured into conical flask. The filtered UCO was then left over night in order for unwanted residue to settle at the bottom of the flask. The UCO was decanted and all the residual matters were removed.
The experiments were started primarily selecting the process parameters as the reaction temperature of 60 C, catalyst concentration of 1 wt% of oil, reaction period of 2 h, stirring speed of 150 rpm and methanol to feedstock molar ratio of 6:1 and then the parameters were varied over a range.
Firstly, the required volume of methanol was measured usingameasuringcylinderandpouredintoaconicalflask.Then
usinga weighing scaletheamountofpotassiumhydroxide was measuredandpouredintothesameflaskcontainingmethanol. The opening of the conical flask was wrapped with aluminium foil to prevent the potassium methoxide generated from reacting with air. This was because any reaction with air might compromise the reaction with methanol and catalyst.
Secondly, the feedstock UCO/AF was preheated in another conical flask for 25 min to a temperature of 60 C using the water bath shaker. Then the potassium methoxide solution was poured into the flask containing the preheated UCO/AF. The overall solution was heated for 2 h, while continuing stirring at the speed of 150 rpm. Thus the transesterification process occurred.
After 2 h, the mixture was rested at room temperature to settle for a minimum period of 12 h until when the distinct separation of layers was visible. Biodiesel (golden colored) was formed at the upper layer, while glycerin (dark brown) was settled at the bottom layer. The crude biodiesel was extracted using a pipette and transferred to another conical flask.
The final step involved washing of biodiesel with distilled water. This step was crucial to remove the excess glycerin, methanol or potassium hydroxide. Initial washing caused the water to turn murky thus was left to settle for an hour. The washed biodiesel was then extracted from the biodiesele water mixture. The washing process was repeated until the water became clear. The pure biodiesel was then extracted with a pipette and stored in a conical flask.