In this brief guide, we will answer the question ‘ How to get citric acid from a lemon?’ If you are carrying out a process that calls for citric acid, this guide on ‘ How to get citric acid from the lemon’ might help you. Citric acid is known for its sour taste found in citrus fruits. Industrially, however, it is produced from a fungus called Aspergillus Niger.
How to get citric acid from a lemon?
Although lemons are rich in citric acid, they are not as concentrated as pure citric acid. If it is possible to use lemon juice as a substitute in the recipe, you should use it instead of citric acid. Lemon is superior because it has health benefits to offer that citric acid doesn’t. The concentration of citric acid in a lemon is only five to eight percent; the rest of it is just juice. While using citric acid instead of lemon juice, you may need to increase the quantity.
The sour, distinct taste of citric acid helps bring out the flavor in some foods and beverages. Citric has plenty of other food-based uses as well. The crucial application of citric acid in food is as a flavoring agent and pH stabilizer. It is used as a preservative in canned goods such as a preservative by acting as an antioxidant. Other uses are for drying out fruit and cheese-making.
If you don’t have a ready-made citric acid powder, you can extract it from lemons using the process below. A science laboratory is fully- equipped to enable you to carry the experiment.
98 % Conc. Sulphuric acid 20.9 ml
Calcium chloride 28.5 g
Sodium hydroxide pellets make 10 % solution by adding 90 ml water to 10 g sodium hydroxide.
While handling strong chemicals, be sure to wear gloves and safety goggles.
Collect at least 450 ml of lemon juice.
Add 10% sodium hydroxide solution to neutralize the citric acid solution. To be exact citric acid which is an acid that reacts with basic sodium hydroxide. The neutralization reaction occurs to produce Trisodium Citrate and water.
Continue to add sodium hydroxide until the pH of about 8.5 reaches.
Citric acid+ sodium hydroxide 🡪 trisodium citrate + water
Trisodium Citrate is soluble. If you keep adding sodium hydroxide, solids keep getting precipitated out. This reaction makes the solution dark orange.
Now you need a flask and coffee filter to filter out your sodium citrate. This process will take a few hours. You may need to replace your filter paper three or four times.
Once the filtration process is complete, you need to repeat it once more to get a relatively clean solution.
Now weigh 28.5 g of calcium chloride and add 70 ml of distilled water to a beaker. Mix calcium chloride until it dissolves completely.
Add your prepared solution to the sodium citrate, stir and heat it until it boils.
Here Trisodium Citrate reacts with calcium chloride to make tricalcium dicitrate and sodium chloride. The chemical reaction that takes place is called double displacement.
Trisodium citrate + calcium chloride —> tricalcium dicitrate + sodium chloride
After the solution gets hot enough, you see precipitates of tricalcium dicitrate. The sodium chloride dissolves in the solution.
Stir for a few minutes. When taken off the heat, the precipitates settle at the bottom.
Filter it again. Preferably by vacuum filtration to get rid of the liquid and gather calcium citrate.
Add hot distilled water to calcium citrate to wash it. Wash it three times and remove water by vacuum filtration.
Move calcium citrate to a beaker and pour sulfuric acid. Mix it thoroughly.
In this step, the calcium citrate reverts to citric acid. Citric acid readily dissolves in water, while calcium sulfate is a side product.
Tricalcium dicitrate + sulfuric acid 🡪 citric acid + calcium sulfate
Calcium sulfate is insoluble, which makes it easy to separate.
Now assuming that we recover 76 g of calcium citrate, we add 20.9 ml of sulphuric acid. Be sure to add no more than 20.9 ml.
Stir it for several minutes until the reaction is complete. Now filter off calcium sulfate using vacuum filtration if you can otherwise use gravity filtration. While the filtration process occurs, stir it to release as much citric acid as possible. Add a little bit of water two times to dissolve the citric acid.
Now to get pure citric acid, we need to remove water by evaporating the filtrate.
It needs to be heated to around 80 C but kept below boiling point; Meanwhile, stirred vigorously.
When the water evaporates, the solution gets a yellow tinge because the citric acid solution is not pure. The opaqueness is because some calcium citrate is left behind. Remove the impurities using the filtration process.
Boil it again on the hot plate until left with 70 ml of liquid.
Let it cool down and filter it through a coffee filter.
The clear solution that you get is a citric acid solution.
Let it evaporate for a few weeks to allow citric acid to precipitate out. Separate the crystals from the wastewater and let it dry.
In this brief guide, we answered the question ‘How to get citric acid from a lemon?’. We also looked at three different chemical equations that are involved in the process.