Biodiesel Pre Lab Introduction The purpose of this experiment is to convert vegetable oil into biodiesel The process used is transesterfication of triglycerides with methoxides Preparing a methoxide solution synthesizing biodiesel separating products and gas chromatography are all used in this lab Also The determination of free fatty acid FFA is also determined in this lab Studies in biodiesel range in many different areas and the science used in this lab also ranges to many different areas A specific study in china used gas chromatography as in this procedure to characterize a biodiesel compound Transesterfication was used to synthesize the oil as in this lab and a KF Sm2O3 catalyst was used1 In another biodiesel study a catalyst is in development that is very eco friendly made from crab shell waste and sunflower oil The process to synthesize the diesel is transesterfication They also used a gas chromogram along with X ray and NMR studies to characterize this biodiesel2 Finally in another study synthesized calcium methoxides from quick lime in a refined palm oil biodiesel production3 Biodiesel is a vegetable oil or animal fat based diesel fuel with long chains of esters One of the main chemistry concepts used in this lab is a transesterification reaction This is the main process used in the synthesis in this procedure and the basic premise of this concept is that an alcohol reacts with an ester group to yield another ester and a different alcohal4 Typically animal fats and vegetable oils are used due to long carboxylic acid chains attached to glycerol chains Specifically a triglyceride reacts with a methanol to form fatty acid methyl esters and glycerol Methanol and ethanol are typically used in this process due to the steric hindrances that larger alcohol have Steric hindrances are slower reaction rates due to larger atoms or groups6 These larger alcohols also have a higher volatility of the produced biodiesel This means they are easily evaporated or have low boiling points A catalyst is used to drive this reaction in this lab Catalysts lower the activation energy of reaction to make them more thermodynamically favorable Methoxides are synthesized in order to use transesterification to switch ester groups with triglycerides Methoxides are organic salts Gas chromatography is used in this lab to test the produced biodiesel and determined the FFA content Gas chromatography is separating the components of a solution by using the different boiling points and analyzing the different components FFA s or free fatty acids are unesterfied fatty acids that need to be neutralized because they did no convert in the transesterification process This can be done by acid catalyzed esterification A small amount of 2 base can be used to neutralize this which turns FFA s into a soap solution This process is known as saponification The soap will then separate out with the glycerol Starting materials if the contain water will hydrolyze with triglycerides to form carboxylic acid salts or soaps This is a more favorable reaction than the transesterification Density separation is when different types of reagents will separate over time du to different densities They can then be easily extracted Also this means reagents that are polar will separate from non polar ones making it easy to separate these too Biodiesel titration is another concept used in this lab This can be used in the process of saponification to neutralize FFA s and form soap This titration is done in a slight excess in order for the reaction to proceed correctly Table of Reagents Reagent Vegetable Oil Molar Mass g mol N A Boiling Point oC N A Melting Point oC 22 Density g cm3 0 93 Methanol 32 04 64 7 97 6 0 79 Potassium Hydroxide Potassium Methoxide 2 Propanol 56 11 1384 370 2 04 70 13 92 250 0 85 60 10 82 89 0 79 Phenolphthalein 318 32 N A 260 1 27 Glycerin 92 09 290 17 8 1 26 Water 18 02 100 N A 1 00 Heptane 100 20 98 90 0 68 Hexane 86 18 69 95 0 65 Sodium Sulfate 142 04 1429 884 2 66 Methyl Ester Biodiesel 214 35 267 5 2 NA 3 Hazards Really It s vegetable oil You can drink it Skin eye ingestion irritant Makes you go blind Skin eye ingestion irritant Skin eye ingestion irritant Skin eye ingestion irritant Skin eye ingestion irritant Gives explosive diarrhea Skin eye ingestion irritant Also a good song by fuel Hazardous in copious amounts Skin eye ingestion irritant Skin eye ingestion irritant Skin eye ingestion irritant Skin eye ingestion irritant Burns well I think Procedure A complete procedure is in the lab manual4 A Preparing Methoxide Solution 1 Measure 250mL of vegetable oil into a 500 mL flask Heat this solution while monitoring the temperature with a thermometer i Heat until 55 C ii Do not exceed 60 C due to the fact that methanol boils at 65 C 2 Add 50mL of methanol in a 125mL flask with 1 41g of KOH i Cover with parafilm to prevent water absorbtion ii Dissolve the KOH in the flask B Transesterification 1 When the heating solution reaches 55 C add the methoxide solution i Mix the solution completely 2 Bring the temperature back to 55 C and maintain that temperature for an hour C Determining the FFA Content 1 Measure 40mL of 2 propanol into a 125mL flask 2 Add 4mL of waste oil into the flask and then swirl in order to mix the solution 3 Warm the solution while stirring on a hotplate so the solution is no longer cloudy 4 Add three drops of phenolphthalein 5 Obtain 20mL of 1 KOH and Moht pipet 10mL dropwise to the methanol solution or until it turns pink and persists for more than 15 seconds 6 Make note of the final volume used to titrate this solution 7 Divide the result by four and for every mL of KOH used an additional 1g of KOH will be needed for the methoxide solution D Finishing 1 Once the reaction progresses for an hour the flask can be removed from heat and contents can be poured in a poly bottle 2 Allow biodiesel to separate from the glycerin for a day 3 Pour off the biodiesel layer in a separate container 4 Wash the biodiesel i Pour half as much water into the solution as there is biodiesel allow to separate then pour off the water ii Do until water is no longer cloudy E Testing 1 Wash Test i Put 150mL of the biodiesel into a clear poly bottle ii Add 150mL of DI water to this and cap the bottle tightly iii Shake rattle and roll for 15 seconds or however long is necessary Maybe do a little Harlem shake or shake rattle and roll 2 Methanol test i Dissolve 25mL of product into 225mL of methamphetamines ii The biodiesel