Optimization process condition for deacidification of palm oil by liquid-liquid extraction using NADES (Natural Deep Eutectic Solvent)

One of many steps in palm oil refining process is deacidification which aims to separate free fatty acids and other compounds from the oil. The deacidification process was using a green solvent, known as NADES, that consisted of betaine monohydrate and propionic acid at molar ratio of 1:8. In this study, the process conditions were optimized using the response surface method (RSM) through central composite design in order to predict the maximum distribution coefficient of palmitic acid. The obtained regression equation of the basic model for optimization was: y = 0.717 + 0.003x₁ + 0.043 x₂ + 0.148x₃ - 0.005 x₁x₁ - 0.030 x₂x₂ + 0.047 x₃x₃ - 0.008 x₁x₂ + 0.008 x₁x₃ + 0.033 x₂x₃. The independent variables are x₁ ≡ temperature (40, 60, 80 °C), x₂≡ amount of palmitic acid in the palm oil (2, 5, 8 %) and x3 ≡ mass ratios of oil to NADES (1:2, 1:1, 2:1). The optimum process condition found was temperature of 62.3°C, palmitic acid content of 8%, and NADES to palm oil mass ratio of 1:2, resulting in the maximum distribution coefficient of 0.96.