In: Chemistry
What is the important role of sodium lauryl sulfate play in the adsorption of oil experiment? The materials includes cooking oil, chitosan and lauryl sulfate and different pH water solution. Can anyone explain in details? Thanks
This is an example of the adsorption at oil-water interface. Sodium lauryl sulphate (also known as sodium dodecyl sulfate SDS) and chitosan because of its highly acylated chains acts as emulsifier and also as flocculant for cooking oil adsorption. Sodium lauryl sulphate is an anionic surfactant. In emulsion systems Chitosan interacts strongly through electrostatic interaction forming stable chitosan-surfactant interfacial membranes and the oil droplets which have net positive charge interact and the oil gets adsorbed on the chitosan-SDS adsorbent. In flocculant systems the emulsion droplets carry a net negative charge due to anionic SDS aligned in water at oil-water interface while chitosan carry a positive charge at pH-5 thus facilitating the electrostatic interactions but the elctric double layer surrounding the SDS coated oil droplets are assumed to be heavily compresses at this ionic strength and it is likely that underlying mechanism is not electrostatic but hydrophobic interactions.