Coupling electrooxidation and Oxone for degradation of 2,4-Dichlorophenoxyacetic acid (2,4-D) from aqueous solutions

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most applicable of herbicides in the world. The presence of 2,4-D in aquatic environment threatens the human health and ecosystem. In current study, a hybrid process was conducted based on the combination of electrooxidation (EO) and Oxone for integration of hydroxyl and sulfate radicals. The operational parameters were investigated and 91% of 2,4-D was removed under the best condition (pH = 4.0, Oxone = 3 mM and 30 mA/cm2). The combination of Oxone and EO indicated a synergistic effect on 2,4-D removal. NaCl and Na2SO4 as supporting electrolyte demonstrated similar results while NaNO3 reduced the removal efficiency. The presence of Co2+ and Fe2+ enhanced 2,4-D removal through Oxone activation. EO/Oxone/Co2+ could completely degrade 2,4-D during 90 min reaction time while 68.9% of total organic carbon was eliminated within 3 h. Scavenging experiments showed that the contribution of sulfate and hydroxyl radicals was nearly the same in 2,4-D degradation in EO/Oxone while sulfate radical was prevailing species in EO/Oxone/Co2+. The performance of EO/Oxone was also examined on a real matrix.