Phosphate and Phosphonate-Based Ionic Liquids as New Additives in Foeniculum vulgare Essential Oil Extraction

The effect of the addition of four different halide-free ionic liquids (ILs) during the maceration step on Foeniculum vulgare essential oil (EO) extraction by hydrodistillation was investigated. The EO yields and their chemical composition were also evaluated, as well as the possibility of reusing the IL aqueous solutions. Although all the investigated ILs were able to increase EO yields, 1,3-dimethylimidazolium dimethylphosphate (IL1) showed the best performance. In particular, the 1 : 1 IL1-water mixture increased the EO yield by, similar to 40%, even after three reuses, maintaining practically the same volatile profile.