Ionic liquid-mediated microwave-assisted simultaneous extraction and distillation of gallic acid, ellagic acid and essential oil from the leaves of Eucalyptus camaldulensis

Abstract

Abstract The ionic liquid (IL) microwave-assisted simultaneous extraction and distillation (ILMSED) of gallic acid (GA), ellagic acid (EA) and essential oil (EO) from the powdered leaves of Eucalyptus camaldulensis was investigated and optimized. A wide range of imidazolium-based ILs with different cations and anions were evaluated for this process, and compared in terms of the GA, EA and EO yields. Notably, 1-butyl-3-methylimidazolium tetrafluoroborate was used as an extraction solvent in the current study. The ILMSED process for the three analytes (i.e., GA, EA and EO) was optimized by a series of single factor experiments, followed by response surface methodology analysis. The optimal conditions were determined to be a liquid-solid ratio, microwave irradiation time and microwave power of 50 mL/g, 20 min and 440 W (0.34 W/g at a [C 4 mim]BF 4 concentration of 0.5 M), respectively. The main constituents found in the EO extracted from the leaves of E. camaldulensis were globulol and aromadendrene. A comparison of our ILMSED process with an existing hot water extraction and distillation process revealed that the former approach was much more efficient in terms of being time-saving and low energy. Satisfactory yields of GA (35.2 ± 1.1 mg/g), EA (7.5 ± 0.3 mg/g) and EO (5.8 ± 0.3 mg/g) were achieved.