Guojun Liu
Queen′s University, Canada
Keynote: J Chromatogr Sep Tech
An emulsion may form when impurities in an organic phase are extracted with water in a chemical plant. Crude oil contains water and may form an emulsion stabilized by naturally occurring surfactants. To recover the organic (oily) phase, one normally adds chemicals to break an emulsion and then carries out the separation. However, this process is wasteful and tedious. We report in this talk the fabrication of novel large-pore bi-functional filters that not only break emulsions without adding any chemicals but also rapidly and selectively separate the coagulated oil. Oils had been separated from simple oil/water mixtures that did not contain a surfactant using large-pore super hydrophobic filters that were highly repellent of water but liked oils. However, large-pore filters could not separate oil from emulsions. In the case of an oil-in-water emulsion, for example, the oil droplets surrounded by water and stabilized by a surfactant can be much smaller than the filter pores and appear as water to the pores. Thus, a superhydrophobic filter rejects the oil droplets together with their surrounding water. Our research group has created four generations of bi-functional large-pore filters that can be used to separate oil from various emulsions without adding any chemicals. These filters bear a de-emulsifying polymer on the emulsion-contacting side and a hydrophobic polymer on the other side. Both oil-in-water and water-in-oil emulsions are broken upon contacting the deemulsifying side of the filters regardless if they are stabilized by cationic, anionic, or non-ionic surfactants. The de-emulsified oil then quickly and selectively permeates the superhydrophobic side. Our newer generations of filters can be prepared in a single reaction step from covalently grafting a single polymer to a porous scaffold. The scaffold can be a metal mesh or a cotton fabric. Separations occur rapidly at pore sizes that are orders of magnitude larger than droplets of the dispersed phase.
Guojun Liu, Tier I (senior) Canada Research Chair in Materials Science at Queen’s University, is a leader in polymer materials research. In particular, he has developed various nano- and micro-structured materials from block and graft copolymers; their self-assembly or directed-assembly; and the ability to control and manipulate their shape, size, function roles and stability. The high-flux separation of oil from emulsions by filtration highlights an application of a nanostructured polymer material developed in his laboratory.
