Phospholipid adsorption from vegetable oils on acid-activated sepiolite

Abstract

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 aciddegumming 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.

From microemulsion phase diagrams to hydrophilicity and hydration controlled adsorption: a dissipative particle dynamics modelling study of phospholipid assembly in bio oils

“…The values compare well with prior experimental characterizations in which areas of 1.2–1.3 nm 2 per DPPC lipid have been reported for adsorption from oil onto hydrophilic surfaces, including sepiolite, silica, silica–alumina and bleaching earths. 50,57 The tighter packing in the simulations can be explained by the idealized setup, for example the flat, ideal surface. Notably, the resulting packing density predicted by the model at the hydrophilic substrate is much closer to what would be expected of phosphatidylcholine monolayers (0.6 nm 2 ).…”

“…53,54 It is notable, that most phospholipid adsorption studies focus on real bio oil systems including poorly characterised or unknown interfering compounds, and measuring adsorption indirectly through total phosphorus adsorption, or at phospholipid concentrations below the experimentally reported critical micellization concentration (CMC) values to disregard the effect of bulk self-assembly. 50,55–57…”

Adsorption of impurities in vegetable oil: A molecular modelling study

“…In this approach, the undesired components of the oil adsorb to the adsorbent, and can be removed with it. The approach was originally used to remove chlorophyll and pigments, but it can be used also for selective adsorption of hydrophilic impurity species, such as, glycerol [14], mono-and diglycerides [14], fatty acids [17][18][19], soaps [19], or phospholipids [20,21] from the oil. Common adsorbents for the process include, e.g., silicates, silica-based adsorbents, and organo-clays, ion exchange resins, and activated carbon [14,17,18,20,22,23].…”

Optimization of bleaching power by sulfuric acid activation of bentonite

“…Since this decomposition causes a color change from white to grey-blue, bleaching power is more conveniently measured by the adsorption of chlorophyll rather than βcarotene. Besides the carbonaceous materials (Omar et al, 2003), a variety of raw and modified clays such as attapulgite (Huang et al, 2007), sepiolite (Tian et al, 2014;Laatikainen et al, 2015), and bentonite (Komadel, 2003;Noyan et al, 2007) have also been used for bleaching of various edible and mineral oils. In general, raw and acid activated clays are called "fuller earth" and "bleaching earth", respectively (Zschau, 1985;Emmerich et al, 2010;Sohling et al, 2010;Liang et al, 2020).…”