Removal of iopamidol, an iodinated X-ray contrast medium, by zero-valent aluminum-activated H2O2 and S2O82−

Abstract

Activation of H2O2 (HP) and S2O82− (PS) with zero valent aluminum (ZVA, 1g/L) nanoparticles was investigated for the treatment of the X-ray contrast medium and micropollutant iopamidol (IOPA; C17H22I3N3O8; ≈777g/mol) at pH 3. IOPA (2.6μM) degradation was followed in different water matrices (distilled water, tap water, raw surface water and tertiary treated sewage effluent). Both oxidants could be activated with ZVA resulting in a dramatic enhancement of IOPA degradation due to accelerated hydroxyl and sulfate radical formation. The ZVA/PS (0.5mM) treatment was more effective than ZVA/HP (0.25mM) oxidation resulting in 95% IOPA removal after 120min. IOPA and dissolved organic carbon (DOC) abatements were inhibited when IOPA was treated in real water and wastewater. After 120min treatment, IOPA removals decreased from 95% (PS/ZVA) and 41% (HP/ZVA) in distilled water to 29% (PS/ZVA) and 13% (HP/ZVA) in surface water, respectively. IOPA could not be removed with the PS/ZVA process in treated sewage, although DOC removal was still substantial (28%). For the HP/ZVA combination, 24% DOC accompanied with 20% IOPA removal was achieved after 120min in the same wastewater sample. Changes in acute toxicity were followed during PS/ZVA treatment of IOPA in distilled and surface water. These results exhibited a fluctuating trend depending on the sensitivity of the test organism (Vibrio fischeri and Pseudokirchneriella subcapitata) and water matrix. A genotoxic activity analysis was also conducted and the UmuChromo assay indicated that the original and treated IOPA solutions were not genotoxic but cytotoxic. The potentials and differences of PS/ZVA and HP/ZVA treatment of an iodinated contrast medium could be demonstrated in this study.