Sonochemical degradation of polycyclic aromatic hydrocarbons: a review

Combined cavitation and oxidation allow efficient and cheap removal of polycyclic aromatic hydrocarbons (PAHs) following the generation of reactive oxygen species. Here, we review the removal of PAHs by sonochemistry, biodegradation, photodegradation, Fenton oxidation, ozone oxidation, and photochemical oxidation. We discuss factors controlling cavitation under sonochemical irradiation in various reactors such as ultrasonic horn, ultrasonic bath and longitudinal horn. The longitudinal horn-type sonochemical reactor has wide operating capacity of 9.5 L with higher power dissipation of 9.5 W and energy efficiency of 59.2%. Degradation is highly dependent on gas sources such as CO2, Ar, O-2, H-2, and He. Phenanthrene degradation efficiency increases from 30 to 70% with decreasing phenanthrene concentration from 4 to 1 mg/L at constant ultrasound frequency 20 kHz at 25 degrees C. Reduction of phenanthrene in sediments ranges from 12.9 to 48.3%. Combined ultrasonic and photo-Fenton oxidation treatments of PAHs are more efficient than solely ultrasonic.

Automated summary

The efficient and cost-effective removal of polycyclic aromatic hydrocarbons (PAHs) can be achieved through combined cavitation and oxidation processes. Various methods such as sonochemistry, biodegradation, photodegradation, Fenton oxidation, ozone oxidation, and photochemical oxidation have been reviewed for PAH removal. Factors controlling cavitation under sonochemical irradiation, the performance of different reactors, and the influence of gas sources on degradation efficiency have been discussed. Further research has shown that the reduction of PAHs can be significantly improved under certain conditions and with the use of specific gases.