Iodinated contrast media electro-degradation: process performance and degradation pathways.

Area of Science:

• Environmental Chemistry
• Electrochemistry
• Water Treatment

Background:

• Iodinated contrast media (ICM) are widely used in medical imaging.
• These compounds can persist in wastewater, posing environmental risks.
• Effective treatment methods for ICM in contaminated water are needed.

Purpose of the Study:

• To investigate the electrochemical degradation of six common ICM.
• To evaluate the efficiency of DSA® electrodes for ICM removal.
• To identify degradation pathways and assess potential toxicity.

Main Methods:

• Batch experiments were conducted using DSA® electrodes (titanium coated with mixed metal oxides).
• Constant current conditions were applied with perchlorate or sulphate as supporting electrolytes.
• Degradation efficiency, pathways, and toxicity were analyzed.

Main Results:

• High degradation removal rates (>85% with perchlorate, >80% with sulphate) were achieved.
• Key degradation pathways included reductive de-iodination, amide reduction, and de-acylation.
• Modest toxicity was observed at lower current densities, likely from intermediates.

Conclusions:

• Electrochemical degradation is a reliable method for treating ICM in wastewater.
• Optimized current densities and reaction times are necessary for complete removal.
• This technology can address ICM contamination in hospital and pharmaceutical wastewater.