The water content of [BMIm][NTf2] was determined using a volumetric
Aquastar Karl Fischer titrator (Super Scientech, Shanghai, China) with composite
5 solution as the titrant and anhydrous methanol as the solvent. Each sample was
at least 0.5 g and duplicate measurements were performed.
The absorption spectrum of [BMIm][NTf2] was measured by full wavelength
scan with UV–vis spectrophotometer (PerkinElmer Lamda 900). In a 10 ml
polypropylene centrifuge tube, 1.0 g of the ionic liquid and 2.5 ml of deionized water
were shaken on a vortex mixer for 30 min and centrifuged for 15 min at 4000 rpm.
A 2 ?l aliquot of the aqueous phase was taken with a microsyringe and diluted to
5 ml with deionized water. The absorbance of this solution at maximum absorption
peak was measured and compared with that obtained from dissolving a weighed
amount (0.1–0.6 mg) of the ionic liquid in 5 ml of deionized water