What is the difference between "natural" and synthetic surfactants?
Refraining from any rant against the use and abuse of the term "natural", all those surfactants which are obtained from raw materials of vegetal origin through "simple" processes are commonly called "natural surfactants": here we can range from minimally processed surfactants, extracted directly from plant species naturally rich in saponins, all the way to surfactants that are obtained by reacting compounds of plant origin. The most famous representatives of the latter group is Decyl Glucoside (also known by the marketing-sharpened name Coco-glucoside*) and Lauryl Glucoside, both obtained from the reaction of sugars from corn and fatty alcohols from palm trees oils.
These surfactants have a relatively low cleaning power, making them particularly suitable in fields such as cosmetics, where too high a cleaning power could lead to irritation.
Synthetic surfactants, on the other hand, are… well, all the others.
They are a vast class that includes very different molecules, obtained from different sources through different processes and it is therefore extremely difficult to give a common description. Let's say that when we talk about it in the cosmetics-detergents sector, we usually mean molecules where the processing has been more complex from a chemical point of view, perhaps going beyond the dictates of Green Chemistry.
This class of surfactants usually has significantly greater cleaning and foaming performance, as well as very low production costs: this is why it is widely used in cosmetics, household detergents and in a host of other fields. Typical examples of this class are SLES (Sodium Lauryl Ether Sulfate) and its little brother, SLS (Sodium Lauryl Sulfate).
FUN FACT! Although in recent years they have been branded as the devil, both SLES and SLS actually derive from…. drumroll…. coconut or palm oil, just like their "natural" cousins. The difference is that, to obtain SLES, a reaction called ethoxylation which involves the use of ethylene, a compound mainly produced from natural gas and hydrocarbons, is carried out. This compound can however also be produced by dehydrating ethanol from vegetable sources, making even the infamous SLES absolutely... "green".
(*): Decyl Glucoside (60% C8-C10,40% C12-C14); Coco Glucoside (40% C8-C10, 60% C12-C14)
