Chemical oxidation of ibuprofen in the presence of iron species at near neutral pH

The objective of this work was to evaluate the removal of ibuprofen (IBP) using the oxidants hydrogen peroxide (H2O2) and sodium persulfate (Na2S2O8). The ability of magnetite (Fe3O4) to activate persulfate (PS) and H2O2 for the oxidation of IBP at near neutral pH was evaluated as well. The use of soluble Fe2+ to activate H2O2 and Na2S2O8 was also investigated. H2O2 and Na2S2O8 were inactive during the sixty-minute experiments when used alone. However, activation using Fe2+ increased the removal to 95% in the presence of H2O2 (Fenton reaction) and 63% in the presence of Na2S2O8 at pH 6.6. Chemical oxygen demand (COD) removal was also greater for Fenton oxidation (65%) than for iron-activated PS oxidation (25%). Activation of H2O2 and PS by Fe3O4 was only observed at a high oxidant concentration and over 48 h of reaction time. A second order rate kinetic constant was determined for H2O2 (3.0 ∗ 10− 3 M− 1 s− 1) and Na2S2O8 (1.59 ∗ 10− 3 M− 1 s− 1) in the presence of Fe3O4. Finally, several of the degradation products formed during oxidation of IBP in the presence of H2O2 and Na2S2O8 (activated by Fe2+) were identified. These include oxalic acid, pyruvic acid, formic acid, acetic acid, 4-acetylbenzoic acid, 4-isobutylacetophenone (4-IBAP) and oxo-ibuprofen.

► First ever investigation of IBP removal using PS oxidation. ► First study to investigate oxidation of IBP in presence of magnetite at neutral pH. ► Removal of IBP significantly increased when the oxidants were activated using Fe2+. ► At higher oxidant concentration magnetite effectively degraded IBP. ► First study to present the reaction rate constant for IBP removal by sulfate radical