Saponification – Soap Making Process with Ultrasonics

Saponification is the chemical process of soap making. It is the reaction in which the raw material of fats or oils (triglycerides) react with an alkali reactant in order to form soap. Ultrasonication improves the phase transfer catalysis resulting in increased reaction speed, more complete conversion and avoids the excessive use of base reagents such as potassium hydroxide (KOH) or sodium hydroxide (NaOH). The ultrasonically initiated alkaline hydrolysis can be easily implemented in commercial soap manufacturing. Ultrasonic reactors for saponification produce higher output in shorter time without using any catalyst or reducing the amounts of catalyst used.

Ultrasonically Promoted Saponification

Case Studies of Ultrasonic Saponification

Various research studies have shown that sonication promotes the saponification of triglycerides into soap. Ultrasonic saponification accelerates and increases the conversion whilst saving or avoiding the use of catalyst. This makes ultrasonic saponification a highly efficient production method.

Ultrasonic Initiation of the Alkaline Hydrolysis of Triglycerides (Saponification) Without Phase Catalyst

Mercantili et al. (2013) studied the effects of ultrasonication on the alkaline hydrolysis of triglycerides, known as saponification. They used sonication to initiate the alkaline hydrolysis of sunflower oil. Potassium hydroxide (KOH) was used as alkali base. It was shown that ultrasound is effective as a power source to initiate and drive the reaction, that a high reaction yield is achievable in only 15 min of total power application while working at ambient temperature, and that no detectable by‐products are generated during the reaction. The comparison of an ultrasonic bath and a probe-type ultrasonocator shows the ultrasonic probe to be the superior technique. The study demonstrates that ultrasonic saponification yields in a good conversion without the need for excess alkali or phase transfer catalysis.

Alkaline hydrolysis of triacylglycerol

Ultrasonically Promoted Phase Transfer Reaction for Saponification

Bhatkhande et al. (1998) showed that sonication of vegetable oils such as soybean oil could be efficiently saponified using aqueous KOH and different PTCs at room temperature. The extent of saponification was studied using the saponification value as a reference. Optimizations of various parameters such as time, selection of phase transfer catalysts, quantity of catalyst used, quantity of KOH and quantity of water were carried out using sonication and stirring. To study the effect of ultrasound, the saponification was also carried out at 35ºC under different conditions, namely stirring, sonication, stirring and sonication, and heating at 100ºC. It was found that the heterogeneous liquid-liquid phase saponification of different vegetable oils using aqueous KOH/CTAB was significantly accelerated at 35ºC under sonication and stirring.

High Performance Ultrasonicators

Hielscher Ultrasonics supplies high-performance ultrasonic equipment for lab, pilot and industrial production. The robust and reliable ultrasonicators are used for various sonochemical reactions such as saponification. Hielscher’s probe-type ultrasonicators can be used in batch and inline mode. All important process parameters – amplitude, pressure, temperature – can be precisely controlled and ensure reproducible results.
The digital control automatically records the process parameters and store them on the integrated SD-card. Pre-settings and remote browser control make the sonication process very simple and user-friendly.
For many sonochemical reactions a certain temperature must be maintained, so temperature control is important. Hielscher’s digital ultrasonicators come with a thermo-couple and temperature control. Jacketed flow cell allow for heat dissipation.
The robustness of Hielscher’s ultrasonic equipment allows for 24/7 operation at heavy duty and in demanding environments.
The table below gives you an indication of the approximate processing capacity of our ultrasonicators: