How to Make known Concentration of Potassium Hydroxide Lye for Your Hand Made Soap or Biodiesel

Individuals from any part of the World without the Knowledge of Chemistry can Prepare their own Lye (Potassium Hydroxide) with known concentration from Plant Ash (in this case, dried plantain peels) as the first step to soap-making or self-made Biodiesel production, if the primary intention is to reduce or eliminate cost and ensure Autonomy; by following the simple steps prescribed below:

Preparation Of Plantain Ash Or Starter

Discarded Plantain bunch or Peels can be collected and well dried (under the sun) to generate dry lye starter. The starter burns easily to ash without the usual formation of unwanted Charcoal in the case of Hard wood. The Ash must be well packed into a plastic bucket with a small hole pre-pierced with nail at the bottom of the side of the bucket.

Preparation Of Lye Water

Rain Water must be pre-collected, boiled and poured gradually on the top of the Ash with the minimum amount of boiled water required being at least half of the volume of the bucket. Though the water remains immobile (after the initial vigorous bubbling effect) at the first instant, it begins to sink in after some time and flows out as lye water from the hole, and is collected with a heat-able material placed at the bottom. When all the water has sink through the Ash, the lye water is transferred to the fire to be evaporated (concentrated).

Concentration Of Lye Water

Lye water generated in this form is an absolutely diluted Potassium Hydroxide (KOH) which is one of the two major Alkaline (KOH and NaOH) used in soap making or Bio-diesel production. In traditional soap making, Lye water has to reach an effective concentration before it can be suitable for soap making. Such process involves: Continuous boiling to evaporate the water content, Re-pouring the lye through the pre-used ash in the bucket, re-boiling, and testing the required concentration at every interval using one or both of the Test methods below:

The Chicken Feather Test

This involves placing a chicken feather into the Lye. If the Feather dissolves, the lye is concentrated enough to make the soap, if it does not dissolve, further boiling and pouring through the ash is carried out to increase the concentration until the result is positive. A precaution to be learnt from this procedure is that care must be taken when handling lye because it can be hazardous (burning sensation) when in contact with the skin or the eyes.

The Fresh Egg Test

In this case, fresh egg (with the shell) is placed into the lye after cooling. If the Egg sinks to the bottom, the lye solution is not yet concentrated enough; If it floats at the top of the lye solution, it is over concentrated. But if the egg floats such that it is covered with just little lye at the top, it is in the right concentration for soap making. And it is ready to be used.

But standard lye crystals (potassium hydroxide crystals) can be produced from lye generated by this process by exposing concentrated lye solution to the sun to evaporate the water content. KOH produced in this form is useful in the preparation of Bio-diesel. Otherwise, any concentration of KOH required for Bio-diesel production or soap preparation can be calculated at any interval of the preparation process (or after the preparation) by using a more accurate calculation model formulated to create a standard chemical from plant Ash for anybody no matter how isolated in any part of the World.

The Calculation Model

Actual laboratory concentration of KOH in the lye solution at every phase can be calculated using knowledge of elementary Chemistry which involves titrating an acid against the lye solution in the presence of an indicator to detect the end point. Materials required for this process are: Burette, Pipette, Volumetric Flask, Beaker, and a retort stand. Other chemicals required are acid and indicator.

A simple process involves,

1.Clamp the Burette to the Retort Stand at the upper part with the lever, rinse, and use the beaker to Pour 10% (2.87Mol/dm³) Hydrochloric Acid (HCL) into the Burette to the mark level.

2.Use the Pipette to measure 25cm³ of the lye solution into the volumetric flask and add two drops of phenolphthalein. This will assume a pink colouration.

3.Take down the volume of the the filled Burette as V₁ and place a white background at the bottom of the retort stand and titrate the acid against the lye solution by carefully opening the Burette tap gradually releasing the acid into it until the colour just begins to change. At this point, begin to add the acid in drops until the last drop where the lye solution just turn from pink to colourless.

4. Observe the volume of acid used by placing your eyes at the bottom of the convex mark formed at the top of the acid in the Burette and take down the reading as V₂.

5.Calculate the actual volume of acid used V_a by subtracting V₂ from V₁ thus, V_a=V₁-V₂ .

6.Because it is KOH and HCL, The stoichiometry is 1:1 Therefore, C_aV_a=C_bV_b. Where C_a=concentration of acid=2.87Moldm^-3, V_a=volume of acid, C_b=concentration of KOH or lye solution, V_b=volume of lye solution used in the reaction=25cm³

But, C_b=(V_a/V_b)C_a=(V_a/25)2.87Moldm^-3

This is the standard Value of KOH in the lye solution. And it is useful for accurate reaction in Bio-diesel production, Soap Preparation, or any other endeavour

For further reading on the use of plantain peel to prepare KOH lye solution, visit: http://www.bioline.org.br/request?ja02016