Can you make soap from used oil? Yes: our chemical experiment on saponification

Oct 17, 2024

October 15, 2024

The soap it is one of the household products most used by man. Despite its enormous global diffusion and constant daily use, the chemistry behind its production is often little known. In this video we want to explore the process saponificationthe reaction chemistry which allows you to transform oils and fats in soap. To do this, we made a experiment in which we try to transform the used frying oil in soap for the hands.

There saponification is a chemical reaction between a fat (or oil) and a strong base, such as sodium hydroxide (NaOH), commonly known as soda caustic. Fat is a substance made up of triglyceridesmolecules made up in turn of a glycerol molecule linked to three fatty acids. When the fat is reacted with caustic soda, the triglyceride molecules are broken down, releasing glycerol and forming the soapwhich consists of salts of acids fats.

In ours experiment we started with frying oil eggplant. This source of fats, however, unlike “clean” olive oil, also contains different molecules odorous dissolved within it. Frying, in fact, triggers the reaction Of Maillard and produces different aromas which give the classic smell to frying oil.

To overcome this problem we tried to cover these odors by adding the aroma of lavender pure. Plus, to get a soap violawe also added two dyes: one red and one blue. Once all the ingredients were added, we left the soap in the molds for 24 hours. To discover the process with all the steps and necessary tools, we recommend watching the video.

Result of our experiment? The soap it solidified only after 2 months. Probably, what could have caused this “delay” is the excessive amount of dyes added. Also, on top of this, the fried smell was not successfully covered by the lavender aroma. Consequently, making soap from frying oil is not advisable, due to the strong presence of odorous molecules.

Alexander Marchall

Alexander Marchall is a distinguished journalist with over 15 years of experience in the realm of international media. A graduate of the Columbia School of Journalism, Alex has a fervent passion for global affairs and geopolitics. Prior to founding The Journal, he contributed his expertise to several leading publications.