Novel surface-active ionic liquids used as solubilizers for water-insoluble pesticides

Abstract

Three surface active ionic liquids (ILs) containing organic anions but no halides were used as solubilizers for water insoluble pesticides and as well as alternates for similar ILs with halide anions, which have been increasingly popular in the agricultural practice. The solubilities of five pesticides (fluazifop-P, clethodim, pyrethrin, fosthiazate, and prochloraz) in three aqueous micellar systems, each containing 1-octyl-3-methylimidazolium--tartrate ([OMIM][Tart]), 1-octyl-3-methylimidazolium-l-proline ([OMIM][Prol]), 1-octyl-3-methylimidazolium-l-lactate ([OMIM][lact]), respectively, were measured. The solubilities of all five pesticides were found to increase with the increasing concentrations of ILs solubilzers The enhancements in solubilities were related to surface activities of these SAILs, as indicated in the results of the measurements of their corresponding critical aggregation concentration (CAC), lowest surface tension (γcac), maximum surface excess concentration (Γmax) and minimum area per molecule (Amin) of aqueous solutions of ILs. When comparing with similar ILs with halides as counter anions, we found that these ILs with organic counterions are at least comparable, often more effective solubilizers for all of the five very different pesticides we tested. We conclude that these novel SAILs with organic counterions would serve as at least similarly effective and more environmentally–friendly solubilizers over the more traditional ones with halides.