The main difference between synthetic detergents and soap is the ingredients used during manufacturing. While synthetic detergents are made from petroleum products, manufacturers make soap from lye and natural fat. Unlike soaps, synthetic detergents contain strong antibacterial agents and preservatives.
Another difference is in the way soap and detergents react with hard water. Because hard water contains high concentrations of minerals, these impurities remain on dishes, surfaces and fabrics when washed with soap, causing discoloration. However, synthetic detergents clean fabrics, dishes and surfaces thoroughly, even when hard water is used.
Unlike natural soap, a synthetic detergent breaks up oil and dirt molecules in hard water. It then removes and washes them away, together with dirt from the object being washed. Synthetic detergents, such as those used in dishwashers and washing machines, are stronger than natural soap. In this regard, strong detergents can cause skin irritations and allergic reactions on people’s bodies.
The fact that synthetic detergents are made from industrial byproducts make them less biodegradable than soaps. Synthetic detergents may be the alternative to soaps where the ingredients of making soap are depleted or are needed elsewhere. For example, many countries are turning to vegetable oil for the manufacture of renewable biodiesel fuel.