Degradation of carbamazepine from wastewater by ultrasound-enhanced zero-valent iron -activated persulfate system (US/Fe0/PS): kinetics, intermediates and pathways

Carbamazepine (CBZ) is a common antiepileptic drug. CBZ enters the environment through unreasonable and standardized ways such as human and animal metabolites, discarded drugs, and more than half of its metabolites are released into the environment. Since CBZ is not easy to be degraded, continuous input of CBZ into the water environment will cause long-term impact on the water ecological environment and seriously endanger human health. Aiming at how to degrade wastewater containing carbamazepine, studies were conducted on the degradation of carbamazepine by ultrasound/zero-valent iron/persulfate system (US/Fe-0/PS). Firstly, the removal effects of carbamazepine by different systems, such as ultrasound/sodium persulfate (US/PS), zero-valent iron/persulfate system (Fe-0/PS) and US/Fe-0/PS, were compared; Secondly, the influence of factors, such as ultrasonic power, sodium persulfate dosage, zero-valent iron dosage, reaction temperature, pH, etc., on the reaction was investigated by the control variables method. Results show that ultrasound power, PS concentration, pH and temperature have a great influence on the removal of carbamazepine in US/Fe-0/PS reaction system. Besides, the optimum parameters for degradation of carbamazepine with US/Fe-0/PS reaction system were determined ([CBZ](0 )= 0.025 mM; [PS](0 )= 0.4 mM; Fe-0 = 4.0 mg/L; ultrasonic power = 40 W; T = 30 ?; initial pH = 5.0). Finally, the intermediates and degradation pathways of carbamazepine by US/Fe-0/PS system were analyzed and speculated. It was inferred that two intermediates were generated during the degradation of carbamazepine, mainly through the ring opening and decyclization of piperazine rings. It was proved that process US/Fe-0/PS has a very important application value in the degradation of antibiotic-containing wastewater.