Soap is a mixture of sodium salts of various naturally occurring fatty acids. Soap is produced by a saponification or basic hydrolysis reaction of a fat or oil. Saponification is a process in which esters in fats are hydrolyzed with strong alkaline solution such as sodium hydroxide (NaOH) to produce a carboxylate anion which can act as a surfactant (1).
The manufacture of soap is presented in Figure 1. This continuous procedure is to split, or hydrolyze the fat in a hydrolyzer to separate fatty acids from the more valuable glycerine. The fatty acids are then neutralize with a caustic soda (NaOH) solution to form sodium salts (soap).
The basic chemical reactions in this continuous process of soap making involve two steps: Step 1: Fat splitting and glycerine as the by-product
Step 2: Fatty acid neutralization reaction
The production of soap use a mixture of fats and oils, beef and sheep tallow are the most common fats, and oils from coconut, palm, soy are the most frequently used oils. The soapmaker chooses the raw material according to the properties desired with due consideration of the market price (2).
Soaps are mainly used as a surfactants for cleansing purposes. Soap cleans by altering the surface tension of water, the soap molecules emulsifying and suspending dirt/greasy practices in water to be rinsed away. The two ends of soap have different polarities. The long carbon chain end is nonpolar and hydrophobic, whereas the carboxylate salt end is ionic and hydrophilic. When soap is used with water to clean grease/dirt (nonpolar hydrocarbons), the nonpolar ends of the soap molecules solubilize nonpolar fats and oils that accompany dirt. The water-loving, hydrophilic ends of the soap molecules extend outside where they can be solubilized in water. The soap molecules coat the oily particles, forming clusters called micelles. The hydrophilic end of the soap molecules provides polarity to the micelles, thus emulsifying them in water....