A Note about pH measurement and d-Limonene:
In general, the standard pH test assumes an aqueous solution (water based). The pH of water immiscible solvents (d-Limonene) cannot be measured using typical methods. The chemistry of organic solvents prevents accurate measurements using the 0-14 scale and standard electrodes.
A “relative” pH measurement is obtained by mixing the oil with an equal volume of neutralized water (preferably purified with no dissolved salts). The pH of the water should be measured before mixing. Mix the water and oil for approximately 5 minutes and then allow the phases to separate. Measure the pH of the water phase again. In principle, the pH of the water is now a reflection of the pH of the oil. This is not a precise value, but can be used as an estimation for most applications. Due to the nature of citrus processing, d-Limonene typically contains residual amounts of anhydrous acids and thus yields an acidic “relative” pH value. The most common problem associated with the pH issue is when water collects at the bottom of vessels containing d-Limonene. The d-Limonene is replenished based on the process, but the water is stagnant and continues to become more acidic over time. This can cause corrosion problems.
Florida Chemical does offer a neutralized grade of d-Limonene at additional cost.