Ferrate promoted oxidative cleavage of sulfonamides: Kinetics and product formation under acidic conditions

Publication date: 1 November 2015 Source:Chemical Engineering Journal, Volume 279 Author(s): Chansik Kim , Venkata R. Panditi , Piero R. Gardinali , Rajender S. Varma , Hyunook Kim , Virender K. Sharma Sulfonamide-based antibiotics are often detected in surface water and secondary wastewater effluent and pose an eminent threat for the development of antibiotic resistance bacteria and genes in aquatic environment. This paper presents the kinetics and stoichiometry of the oxidation of sulfonamides (sulfaguanidine, sulfisoxazole, sulfamethizole, sulfamethoxazole (SMX), sulfamethazine, and sulfadimethoxine) by ferrate(VI) (FeO4 2−, Fe(VI)) in the acidic to basic pH range (2.0–9.6); apparent second-order rate constants (k app, M−1 s−1) decreased non-linearly with increase in pH. The specific rate constants for the individual Fe(VI) species (H3FeO4 +, H2FeO4, HFeO 4 - , and FeO4 −) were determined using acid–base equilibria of Fe(VI) and sulfonamides. The reactivity order of Fe(VI) species with the neutral sulfonamide was H3FeO4 + >H2FeO4 > HFeO 4 - , which generally explained the pH dependence behavior of rate constants. Detailed studies regarding the resultant oxidized products (OPs) using liquid chromatography–mass spectrometry/mass spectrometry were performed for oxidation of SMX at different molar ratios of Fe(VI) to SMX (i.e., 1.0–15) and at different pH’s (i.e., 4.0, 7.0, and 9.0); oxidative degradative products...
Source: Chemical Engineering Journal - Category: Chemistry Source Type: research