Microemulsion breakdown by pervaporation technique: the cyclohexane/water/n-butanol/sodium dodecylsulfate system

Preliminary results obtained on destabilizing microemulsions made up of cyc lohexane, water, n-butanol, and sodium dodecylsulfate (SDS) using pervapora tion membranes are promising. The hydrophobic/hydrophilic character of the membrane employed makes preferential removal of one of the microemulsion co mponents possible. This leads to microemulsion breakdown. While cyclohexane permeates through hydrophobic polydimethylsiloxane membranes, water permea tes through polyvinyl alcohol membranes. Removal of either component leads to microemulsion collapse. For instance, when 13.8 vol.% of cyclohexane is removed from the cyclohexane-rich microemulsion: 1:87:8:4 (water: cyclohexa ne: n-butanol: SDS, respectively tin wt.%), destabilization occurs. The flu x rate and the enrichment factor of the component removed through the membr ane were found to be concentration dependent. The variations of both parame ters with time for two microemulsions, one rich in cyclohexane and the othe r rich in water, were examined as function of temperature. The pervaporatio n permeation rate goes up at elevated temperature, but enrichment factor di minishes. The optimum volume of the pervaporate required to produce the des tabilization of the microemulsion changes with temperature according to a l inear Arrhenius relationship with an activation energy of 4.56 kcal mol(-1) . (C) 2000 Elsevier Science B.V. All rights reserved.