CATALYTIC HYDRODEHALOGENATION OF IODINATED X-RAY CONTRAST MEDIA WITH SUPPORTED PALLADIUM CATALYSTS

摘要

Iodinated X-ray contrast media (ICM) is a group of radiopaque pharmaceuticals that are used to aid in brain and body imaging during computer tomography (CT) and other visualization techniques. Their extensive use in hospitals, their inherent stability and hydrophilicity and the lack of effective treatment technologies to remove them from wastewater have resulted in relatively high concentrations of ICM in natural waters when compared to other pharmaceuticals (up to 100 μg/L diatrizoate). Each contrast media has at least one tri-iodinated benzene ring as the foundation of its structure (Figure 1), but of the reported attempts to degrade these compounds, nearly all do so via side chain reactions without successfully deiodinating the contrast media. This presentation reports on the use of hydrogen-activated palladium catalysts for hydrodehalogenation of iodinated X-ray contrast media in aqueous solutions. Reaction kinetics and products are characterized in batch reactor systems and the influence of water quality parameters on catalyst performance is assessed.