Formation, characterization and enzyme activity in water-in-hydrophobic ionic liquid microemulsion stabilized by mixed cationic/nonionic surfactants

The phase behavior of the pseudo ternary system 1-tetradecyl-3-methylimidazolium bromide ([C 14 mim]Br)/Triton X-100/H 2 O/1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF 6 ) has been studied at 35 °C. With the increase in the mole fraction of Triton X-100 in the mixed surfactants, the water solubilization capacity increases and the monophasic area enlarges. The H 2 O-in-[Bmim]PF 6 (W/IL) microemulsion was identified via electrical conductivity measurement. The existence of bulk water in the W/IL microemulsion was demonstrated based on the change of the O-D vibration frequency with content of D 2 O added and confirmed using UV–vis technique with CoCl 2 as probe. Laccase can be solubilized in the W/IL microemulsion and exhibits a catalytic activity. The interface of the W/IL microemulsion has an inhibitory effect on the expression of the laccase activity, and the inhibitory effect is varied with the molar ratio of the mixed surfactants.