PCMX Solubility and Formulation for Water-Based Disinfectant
Question
I dissolved PCMX (Product Name) in Ethyl Alcohol until it was completely clear. However, when I added it to water, it clumped up as shown in the picture. I then tried dissolving it in Propylene Gylcol until it dissolved well, but when mixed with water, the same precipitation issue occurred.
- What is causing this?
- Can this issue be resolved?
- I need advice on how to mix it with water to use as a disinfectant, similar to Dettol.
Answer
Understanding PCMX Solubility
PCMX (Chloroxylenol) in its 100% powder form is not readily soluble in water. It dissolves well in organic solvents like Ethyl Alcohol and glycols such as Propylene Glycol, as you observed. However, when this solution is added to water, the PCMX precipitates out because it is not compatible with the aqueous phase, causing it to clump.
To create a stable, water-based disinfectant solution like Dettol, which also contains PCMX, a solubilizer or surfactant is required to help the PCMX disperse and remain dissolved in water. The "Chloroxylenol (PCMX) (15% Water Soluble)" product is specifically formulated with such ingredients (like C12-15 Pareth and PEG-40 Hydrogenated Castor Oil) to make it water-miscible.
How to Make a Water-Based PCMX Disinfectant
There are two main approaches to achieve a water-based PCMX disinfectant:
Using PCMX 100% Powder with a Solubilizer: You would need to incorporate a suitable surfactant or solubilizer into your formulation to effectively disperse the PCMX powder in water. This requires careful formulation knowledge to select the correct type and amount of solubilizer to prevent precipitation and ensure stability. Ingredients like PEG-40 Hydrogenated Castor Oil are examples of solubilizers used for this purpose.
Using Chloroxylenol (PCMX) (15% Water Soluble): The easiest and most recommended method for making a water-based solution is to use the pre-solubilized version. This product is designed to dissolve directly in water, simplifying the formulation process.
Recommended Usage Rate
For disinfection purposes, especially against viruses like Coronavirus, a concentration of at least 0.12% of pure PCMX is recommended with a contact time of 30 seconds. If using the "Chloroxylenol (PCMX) (15% Water Soluble)" product, this equates to a usage rate of at least 0.8% (since it contains 15% PCMX). Dettol typically uses a higher concentration of PCMX, around 4.8%.
In summary, the clumping occurs because PCMX powder is not water-soluble on its own. You need a solubilizer to disperse it in water, or you can use the pre-solubilized version for easier formulation.
