Queen's University

Universal Janus Filters for the Separation of Oil from Emulsions Stabilized by Ionic or Nonionic Surfactants

Results from the project "Universal Janus Filters for the Rapid Separation of Oil from Emulsions Stabilized by Ionic or Nonionic Surfactants"Existing Janus filters cannot separate oil from emulsions stabilized by non-ionic surfactants. Reported in this paper are universal Janus filters that separate oil from emulsions stabilized by not only ionic but also non-ionic surfactants. To prepare such a filter, poly(dimethyl siloxane) (PDMS) is grafted onto one side of a fabric. The other side is then grafted with a copolymer polysoap bearing pendant oligo(ethylene glycol) monolaurate (EL) chains. Upon contact with an emulsion, the grafted polysoap competes with free surfactants, ionic or nonionic, for adsorption onto the emulsified droplets, drawing them to the surfaces of the fabric fibers, and causes them to coalesce locally. The coalesced oil then migrates to the PDMS-coated side of the fabric and selectively permeates it. These novel filters possess enhanced versatility and showcase a new application for polysoaps. (Read More)