Biodiesel laboratory experiment in Bsc Green chemistry

 Green chemistry

What's Biodiesel ?

Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat (tallow), soybean oil, or some other vegetable oil with an alcohol, producing a methyl, ethyl or propyl ester.

Laboratory method -:

Aim -: preparation of biodiesel from used vegetable oil

Requirements -: conical flask , separators funnel , stirring hot plate , magnetic stirrer , thermometer , aluminium foil , weighing scale , 100g used vegetable oil ,20g of ethanol , 1g of KOH etc.( at the time of presentation you not call etc as like etc but its call exectra).

Theory -: 

The formation of biodiesel from used vegetable based on principle on the principle of trans -esterification . It  is a reaction in which a triglyceride ( fat /oil ) reacts with an alcohol to form ester and glycerol. In this process , used vegetable oil ( triglyceride) reacted with alcohol (ethanol) in the presence of catalyst ( KOH , alkaline, the alcohol reacts with fatty acids to form mono alkyl ester or biodiesel and crude glycerol depending upon the alcohol (type) respective ester formed .

Chemical reaction

Mixture of fatty acid /mono alkyl ester

Procedure -:

Take 1g of KOH in 125ml conical flask after weighing with weighing machine . Add ethanol ( six times of vegetable oil used) in the conical flask and cover it's mouth using an aluminium foil place it over stiring hot plate and mix until KOH is completely dissolved .

Take 100g of used vegetable oil in a conical flask put a thermometer into it and heat and stir upto 60°c using stiring hot plate /heating apparatus and glass rod.

Now add earlier prepared alcohol catalyst mixture in this and again cover the mouth of conical flask with an aluminium foil. Stirr the mixture for 60minute using magnetic stirer / glass rod by holding the temperature at 60°c after 60minute transfer the mixture to a seperatoryvfunnel and allow it to cool down for 20 minute .

Now two layers are visible with upper layer of Biodiesel and lower layer of crude glycerol . Now remove the lower layer into a conical flask by loosing seperatoryvfunnel knob .

Then record the weight of the product formed and then calculate %yield of biodiesel formed from used vegetable oil.

Result -: 

%yield =mass of biodiesel obtained / mass of oil used * 1000

Precautions and source of error-:

1.  Add alcohol about six times to the volume of vegetable oil used otherwise some amount of glyceride impurity left behind causing decreases in % yield

2. Seperate the two layer carefully using a separatory funnel  .

3. Cover the mouth of conical flask with aluminium foil to keep the alcohol vapours from escaping.

Advantage of biodiesel oil intel life -:

Biodiesel is a domestically produced, clean-burning, renewable substitute for petroleum diesel. Using biodiesel as a vehicle fuel increases energy security, improves air quality and the environment, and provides safety benefits.