Abstract:
Vegetable oils are essential for our diet and are used in various industries. However,
during high-temperature frying, toxic compounds can form, leading to environmental
issues. Therefore, it is important to maximize the recycling of used frying oils, which can
be used to produce biodiesel, lubricants, soaps..etc.
In our study, we aimed to valorize used frying oils by transforming them into soap, in
order to reduce their negative environmental impact. We collected samples of waste oils,
which we treated with NaCl and hydrogen peroxide before being used for soap production
according to two methods: the cold method and the semi-hot method. Physicochemical
tests were performed on the oils before and after frying, as well as on the manufactured
soaps to evaluate their quality. The results showed significant changes in the oils after
frying, such as an increase in peroxide value, acid value and moisture, as well as a slight
increase in saponification value, density and viscosity. The soaps produced were also
tested for quality, including pH, moisture content, free alkali content and foaming power.
After the initial drying phase, the soap acquired a semi-solid consistency and was allowed
to dry for 4 weeks. The free alkali levels were similar for the cold process and semi-warm
soap, with a content of 0.20% for each, while the Marseille soap had a lower content of
0.10%. The moisture content of the cold process soap was very low, at 0.50%, while that
of the semi-warm soap and Marseille soap was higher. The pH value and foaming power
of the tested soap sample was similar to that of the Marseille soap.
