Chemical oxidation of ibuprofen in the presence of iron species at near neutral pH.
Résumé
The objective of this work was to evaluate the removal of ibuprofen (IBP) using the oxidants hydrogen peroxide (H(2)O(2)) and sodium persulfate (Na(2)S(2)O(8)). The ability of magnetite (Fe(3)O(4)) to activate persulfate (PS) and H(2)O(2) for the oxidation of IBP at near neutral pH was evaluated as well. The use of soluble Fe(2+) to activate H(2)O(2) and Na(2)S(2)O(8) was also investigated. H(2)O(2) and Na(2)S(2)O(8) were inactive during the sixty-minute experiments when used alone. However, activation using Fe(2+) increased the removal to 95% in the presence of H(2)O(2) (Fenton reaction) and 63% in the presence of Na(2)S(2)O(8) 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 H(2)O(2) and PS by Fe(3)O(4) was only observed at a high oxidant concentration and over 48 h of reaction time. A second order rate kinetic constant was determined for H(2)O(2) (3.0∗10(-3) M(-1) s(-1)) and Na(2)S(2)O(8) (1.59∗10(-3) M(-1) s(-1)) in the presence of Fe(3)O(4). Finally, several of the degradation products formed during oxidation of IBP in the presence of H(2)O(2) and Na(2)S(2)O(8) (activated by Fe(2+)) were identified. These include oxalic acid, pyruvic acid, formic acid, acetic acid, 4-acetylbenzoic acid, 4-isobutylacetophenone (4-IBAP) and oxo-ibuprofen.