How Pickering emulsions are differ from surfactant stabilized emulsions?

Solid Particles. The most notable difference between a Pickering emulsion and a classical emulsion is that, the former one bears solid particles on the interface between two liquid phases serving as the stabilizing agent, whereas the latter uses molecular surfactants to stabilize emulsions.

Do emulsions have surfactants?

An emulsion can be described as a collection of tiny droplets of one liquid (e.g., an oil) dispersed in another liquid (e.g., water) in which it, the first liquid, is insoluble.

What is Pickering effect?

A Pickering emulsion is an emulsion that is stabilized by solid particles (for example colloidal silica) which adsorb onto the interface between the two phases. This type of emulsion was named after S.U. Pickering, who described the phenomenon in 1907, although the effect was first recognized by Walter Ramsden in 1903.

Why surfactants are used in emulsions?

Surfactants and colloidal particles are often used to stabilize emulsions. They reduce the oil-water interfacial tension; thereby minimizes the energy required for emulsion formation.

Which is an alternative to surfactants for Pickering emulsions?

Pickering Water contact angle ° An alternative to surfactants for forming an emulsion is the use of fine particles that form the shell around the oil drop or water drop. The idea of such Pickering Emulsions is very attractive to those who meet it for the first time.

How are casein particles used in Pickering emulsion?

Casein (protein) units are adsorbed at the surface of milk fat globules and act as a surfactant. The casein replaces the milkfat globule membrane, which is damaged during homogenisation. It is possible to use latex particles for Pickering stabilization and then fuse these particles to form a permeable shell or capsule, called a colloidosome.

How did the Pickering emulsion get its name?

Historical perspective Pickering emulsions are named after S.U. Pickering whose paper [4] is considered as the first report of o/w emulsions stabilized by solid particles adsorbed at the surface of oil droplets.

What should the contact angle be for Pickering emulsions?

If the contact angle of the particle with oil is 90° (i.e. it is hydrophobic) the emulsion will be w/o The particles must be considerably smaller in size than the desired emulsion drop size. In practice the rules are: Use particles with a 90°contact angle or else use Janus particles with are 50% hydrophilic, 50% hydrophobic