Ultrasound was applied using a probe (25 mm diameter) system (Sonics, VCX800, USA), which had a maximum power of 800 W, and operated at 20 kHz. Duty cycle of ultrasound pulse was set at 50% (2 s on: 2 s off). The ultrasonic emitter was immersed 15 mm into solution contained in a jacketed cylinder reactor (200 mL volume). During the experiments, the temperature of mixture was measured with a digital thermometer located in the center of the reactor and was held constantly at a desired value by a thermostatic bath driving cooling water through jacket. Periodically
agitation (10 s on: 50 s off) was performed to keep the mixture temperature even and the material getting equal irradiation. The reactor was sealed to prevent water leaks during extraction. The sketch diagram of experimental set-up was shown in Supplementary Fig. S1