For a soap to be used for
bathing it must be mild on the skin. Soap is produced by reaction between
alkali and oil (vegetable or animal source). The popular alkali used in soap
making is caustic soda (sodium hydroxide) and caustic potash (potassium
hydroxide). Potassium hydroxide is a more suitable alkali for bathing soap
because it is mild on the skin. However, most soap makers use caustic soda to
make bathing soap because of the high cost of potassium hydroxide. To regulate
the ash condition of caustic soda, a milder alkali (soda ash is blended).
Unripe plantain peel is
scientifically known to be a rich source of potassium. This fact enables it to
be a viable resource for soap makers to access. In this article I will be
highlighting everything needed to extract potassium hydroxide from plantain
peel for production of an improved quality bathing soap.
Materials Required
1.
Unripe plantain peel
2.
Combustion pan
3.
Vegetable oil e.g. palm oil, palm kernel
oil, coconut oil
4.
Water
5.
Spatula
6.
Hydrometer, if available
Extraction of Potassium
Hydroxide from plantain peel
The peel of unripe plantain
is gathered and sun dried for a week. The dried peel is incinerated (burnt) in
a combustion pan to make ash. The ash is mixed with water to form slurry. The
mixture is allowed to stand for the solid particles to settle while the liquid
part is carefully decanted. The liquid part is a concentrated solution of
potassium hydroxide which can be gauged using hydrometer. A reading of 1200 is
ideal for soap production. If the concentration in the solution is not
sufficient, excess water can be evaporated else a little more water is added.
In the absence of a hydrometer an old heuristics used by soap makers could be
applied. This involves the use of fresh egg. If the egg sinks then the solution
is too dilute but if the egg floats the solution is too concentrated. A
solution is deemed okay if the egg is submerged by half of its body size. The
solution will also change red litmus paper blue.
Extracted Potassium Hydroxide
Soap Production
As a model, measure 100ml
of vegetable and react with 100ml of the potassium hydroxide and stir till a
pap-like substance is obtained (tracing) with a liquid substance formed
along-side – this is soap and glycerol being formed. Separate the soap and pour
it into a mould while the glycerol is kept aside for another production like
liquid detergent. Within 10minutes the soap will solidify (set). Take it out of
the mould and allow curing for some days. About 120g of soap is expected with
20ml of glycerol. Cold process of soap production can be used.
Important Things to Note
1.
Soap made with palm oil foams (lather)
moderately and last longer.
2.
Soap made with palm kernel oil foams
vigorously and finishes quickly.
3.
Coconut oil gives soap with improved
characteristics, though lathers vigorously and got used up easily.
4.
Oils and alkali can be blended to obtain a
blend of the individual raw material ability. 60:40 blend or 75:25 blend gives
awesome result.
Properties to Measure if
you want to register your soap with NAFDAC
For the oils you need to
measure and ascertain the following:
1.
Saponification value
2.
Peroxide value
3.
Iodine Value
4.
Free Fatty Acid value
For the soap you need to
measure:
1.
pH value
2.
Foam stability
3.
Total Fatty Matter
Conclusion
Following the guide
provided here will minimize the dependency of soap makers from using imported
raw materials and thereby boost our local economy. It will bring more profit.
The process is environmentally sustainable as plantain peel is a waste that will
be recycled to control pollution. The excellent properties of the bio-alkali
with be imparted on the soap.
For
enquiries mail: odfidservices@gmail.com or visit our Technical Center
The author, Idongesit F.
Oduok, holds a Diploma in Environmental Engineering and is a Masters Student of
Chemical Engineering. He is specializing in design of reactors that utilizes
waste from the environment to useful raw materials.
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