An ultrasonic generator(JY98-IIIDN,Nanjing FeiQiIndustry &Trade Co., LTD. Nanjing- China) was used for extraction (shown in Fig. 2). The immersion stainless steel transducer was of the horn-type with a length of 300 mm and a diameter of 20 mm. delivering a maximum power of 1200 Wat 20k Hz it was equipped with a thermometer to measure the reaction
temperature and inserted in the slurry to introduce ultrasound field. A circulating water bath (HH-2 Guohua Wiring Company, Shanghai, China) was adopted to keepthe reaction temperature at a constant. A magnetic stirrer was used to suspend the particles in the reactor and speed up heat transfer.