Enhanced degradation of 2,4-dichlorphenoxyacetic acid herbicide by CaO2 activated by Fe(II) and ultrasound irradiation: Practical insight and mineralization.

CaO₂ was activated by Fe(II) and ultrasound (US) irradiation to degrade 2,4-dichlorphenoxyacetic acid (2,4-D) for the first time. Among transition metals (Fe, Cu, Mn and Co), Fe(II) had the best performance for the activation of CaO₂. The impact of pH, CaO₂ and Fe(II) concentration was studied, and under optimal situation ∼91% of 2,4-D was degraded during 60 min reaction time. The quenching experiments showed that the hydroxyl radical was the main factor for the destruction of 2,4-D while superoxide anions had a minor role. The bicarbonate ions and acid humic exhibited a strong inhibitory effect on the performance of CaO₂/US/Fe(II) process. Carbon and chlorine mineralization of 2,4-D degradation was investigated; around 41% of C and 35% of Cl were mineralized during 60 min reaction time. The function of CaO₂/US/Fe(II) process was studied on real drainage and other organic pollutants, and the results showed that the CaO₂/US/Fe(II) process can be practical for water treatment. Finally, intermediates of 2,4-D degradation were identified, a pathway was proposed, and the toxicity of intermediates was assessed by ECOSAR software. [ABSTRACT FROM AUTHOR]