Exploring the potential of Fe(III)-EGTA and Fe(III)-DTPA as the catalysts to enhance UV/persulfate in the degradation of aqueous sulfamethazine

The combination of UV and water-soluble Fe(III) complexes is an effective method for generating Fe(II) in situ for activating advanced oxidation processes. This study explored the potential of Fe(III)-diethylenetriaminepentaacetic acid (Fe(III)-DTPA) and Fe(III)-ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (Fe(III)-EGTA) in activating the UV/persulfate (UV/PS) for sulfamethazine removal. The initial screening showed that Fe(III)-EGTA and Fe(III)-DTPA could significantly improve the rate of sulfamethazine removal. The optimum molar ratios of persulfate to Fe(III)-DTPA and Fe(III)-EGTA were 100:1 and 100:2.5. The predicted percentage of sulfamethazine removal under the optimized conditions, obtained using response surface methodology, was ~99% for both catalysts. The pH range of 6 to 8 did not significantly affect the performance of UV/PS in the removal of sulfamethazine. The percentage sulfamethazine removal in the selected water samples was ranged from 93.6% to 99.6%, agreeing with the predicted value. The performance of both catalysts in activating UV/PS is comparable with that of the frequently used Fe(III)-EDDS. PRACTITIONERS POINTS: The potential of Fe(III)-DTPA and Fe(III)-EGTA in activating UV/persulfate (UV/PS) was explored. Fe(III)-DTPA and Fe(III)-EGTA improved the performance of UV/PS in sulfamethazine removal. Fe(III)-DTPA and Fe(III)-EGTA are effective in catalyzing UV/PS under pH 6 to 8. The performance of Fe(III)-DTPA and Fe(III)-EGTA is comparable with well-studied Fe(III)-EDDS.