Rosmarinic acid enhanced Fe(III)-mediated Fenton oxidation removal of organic pollutants at near neutral pH.

Abstract In this study, we reported that the presence of rosemary acid (RA) could strongly enhance the Fe(III)-mediated Fenton oxidation of 2,4-DCP as the model contaminant at near neutral pH. This enhancement was verified by the strong chelating and reducing ability of RA, which could prevent ion precipitation and accelerate the Fe3+/Fe2+ cycle. Radical quenching experiments and electron paramagnetic resonance confirmed the existence and roles of hydroxyl radicals in the Fe3+/RA/H2O2 system. Lot size optimized experiments were executed to achieve efficient 2,4-DCP degradation (99.93%) under the optimum conditions of 100 μmol/L Fe3+, 100 μmol l/L RA and 8 mmol/L H2O2 within 60 min. In addition, co-existing metal ions, inorganic anions and natural organic matters were proved that they could inhibit removal efficiency and rate at varying degrees. Total organic carbon and chloride ion measurements were employed to probe the mineralization of organic matters (including RA and 2,4-DCP). This study provides a new modified Fenton system to enhance the oxidation removal of refractory organics in water and will enrich the understanding on effective H2O2 activation at neutral pH.