Low-Temperature Plasma Enhanced Generation of Active Species to Efficiently Degrade Refractory Organic Pollutants

To enhance the contact opportunities between active species and organic pollutants, thereby increasing the total organic carbon (TOC) removal rate of organic pollutants. This study employed a self-designed underwater arc discharge (UAD) plasma reactor, which combined advanced oxidation process (Fe2O3-CoFe2O4/PMS) and low-temperature plasma technology to degrade refractory organic pollutants (i.e. phenol, p-chlorophenol, p-nitrochlorobenzene). The results illustrated that the plasma/PMS/Fe2O3-CoFe2O4 system possessed high degradation efficiency and TOC removal rate towards three target pollutants (phenol: 99.8%, 96.12%; 4-CP: 98.4%, 86.48%; p-NCB: 99.9%, 88.31%). With the help of in-situ variable temperature EPR and Indigo colorimetry method, ·OH, SO4·-, O2·-, 1O2 and O3 were identified as the main reactive oxygen species (ROS) for the degradation of target pollutants, revealing the synergistic catalytic mechanism between plasma and Fe2O3-CoFe2O4 for PMS activation and inferring the degradation pathways of target pollutants. The results confirmed that the plasma/PMS/Fe2O3-CoFe2O4 system was feasible for the degradation of refractory organic pollutants, has the advantages of high efficiency and low energy consumption, and could provided an effective strategy for the treatment of refractory organic pollutants in groundwater/soil.