Mechanism Investigation and Standardized Equipment Development of Sequential Multi-Frequency Ultrasonic Extraction for Plasticizers in Polymer Materials

Phthalates (PAEs), commonly incorporated into materials such as polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC), are easily to migrate readily into the surrounding environment, which have become a matter of increasing concern. Traditional PAEs extraction methods have been prevented by long extraction times and high costs, requiring substitute to accelerate the extraction speed while reducing extraction costs. Ultrasonic-assisted extraction facilitates the release and dissolution of target compounds through the combined effects of acoustic cavitation and molecular vibration acceleration, which could be an effective means to overcome the limitations of traditional extraction methods. Herein, we have developed a four-frequency composite ultrasonic extraction technology for PAEs, with a recovery of 95.2%, approximately 38.2% higher than mode MU 20 kHz. Besides, an in-depth study on the mechanism of ultrasound-assisted extraction with sequential multi-frequency was conducted and we confirm that stepped-frequency ultrasound could achieve precise control of cavitation effects by dynamically adjusting frequency distribution, ensuring high extraction efficiency while maximally protecting the PVC matrix structure, providing a new technical path for efficient and green recovery of plasticizers.