How does the pH of a solvent influence the solubility of turmeric in it?

Abstract

Turmeric is a culinary spice used in many meals particularly in traditional Indian cuisine. Turmeric has a bright orange colour that is due to the presence of curcumin within it. Because of it’s bright colour, it is important to be able to easily remove turmeric stains from clothing. In my research I attempted to find the ideal conditions for removing turmeric stains and found that no investigation had been made into the impact the pH of the cleaning agent on its effectiveness.
 In this investigation the solubility of turmeric in 5 different solutions was found using colorimetry. Colorimetry is a scientific technique that is used to determine the concentration of coloured solutions by the application of the Beer-Lambert law. This method allowed the solubility of turmeric to be determined, in a range of different solvents with good accuracy and precision. The experimental results showed that turmeric was more soluble in solutions with higher pH levels as the solubility in 0.2M sodium hydroxide was 17.6mg/mL and in pure ethanol was 10.1mg/mL, while the solubility in hydrochloric acid was only 0.034mg/mL.
 Ultimately, this investigation shows that turmeric is more soluble in basic solutions and hence basic solvents are more effective removers of turmeric stains. A claim which was shown to be true by washing turmeric stained clothes with the solvents and comparing the cleaned clothes. This investigation also shows that turmeric could be used as a pH indicator as it has a different colour in different pH solutions.