Intensification of degradation of acetamiprid by the combination of ultrasonic cavitation with other advanced oxidation processes (AOPs)

The degradation of acetamiprid has been studied using ultrasonic cavitation (US) and its combination with H2O2, Fenton's reagents and photo-Fenton process. Initially, the optimization of operational parameters has been carried out to enhance the performance of US. Maximum degradation of acetamiprid was obtained at ultrasonic power density of 0.22 ​W/mL, operating pH of 2.5 and acetamiprid concentration of 10 ​ppm. Further, the rate of degradation of acetamiprid obtained by US (0.807 ​× ​10-3 min-1) was intensified by combining it with hydrogen peroxide (4.925 ​× ​10-3 min-1), Fenton's reagent (5.593 ​× ​10-3 min-1) and photo-Fenton process (39.907 ​× ​10-3 min-1) with synergistic coefficients of 5.58, 3.14 and 2.04 respectively. The comparison of US and various US based combined processes have been carried out on the basis of mineralization study and cavitational yield. Maximum extent of mineralization of 52.25% and cavitational yield of 5.288 ​× ​10-12 ​mol/J were observed for US ​+ ​photo-Fenton process. Further, the cost of electricity of 4.128 USD/L and power consumption of 41.650 ​kWh/L obtained in the case of US has significantly reduced to 0.233 USD/L and 2.358 ​kWh/L respectively for US ​+ ​photo-Fenton process. The study of effect of radical scavenger (sodium bicarbonate) has confirmed that degradation of acetamiprid using US based combined processes is controlled by OH• radical attack. Comparison of cavitational yield, power consumption and cost of electricity of US and US based combined processes has indicated US ​+ ​photo-Fenton process to be the most energy efficient and cost effective process for the degradation of acetamiprid.