Phospholipid adsorption from vegetable oils on acid-activated sepiolite

In this study, adsorption of natural and model phospholipids (PL) from camelina and rapeseed oils on acid-activated sepiolite has been studied. Adsorption isotherms were determined for total phosphorus and for individual PL at different conditions. Influence of acid-degumming with citric acid as well as of type and ionic form of the phospholipid was investigated. The experimental data were correlated using the Moreau isotherm. The results show that neutral PLs, such as phosphatidylcholines, adsorb as ordered monolayers with molecular area of 1.3 nm 2 /molecule. Phosphatidic acids have similar adsorption capacity when in free acid form but the interaction with the clay surface is much weaker. Sodium salt gives substantially lower saturation capacity because of electrostatic repulsion between the adsorbed PL molecules and between PL and the clay surface. Calcium and magnesium salts have very low capacity and seem to be incapable to form any ordered structures on the clay surface.