For example, the distribution ratio
(D) of benzoic acid is higher than 1 at pH 1.77 and 6.54, while it
falls below 1 at pH 11. In contrast, aniline has D< 1 at pH 1.77, D=1
at pH 6.54 and D> 10 at pH 11. The results suggest that hydrophobic
ionic liquids show high pH-sensitivity to ionic compounds. As a
result, I-PEG is efficiently transferred into hydrophobic ionic liquids
at basic pH, leaving a clarified, penicillin-rich feed stream suitable
for further purification. In addition, imidazole-containing ionic liquids
show natural compatibility with the imidazole-capped I-PEG,
which provides additional driving force for separation of I-PEG into
ionic liquids phase.