Iopromide (IPM), a type of iodinated contrast media, is frequently detected in wastewater treatment plants, sometimes up to 10 µg/L at wastewater treatment plants. ICM doesn't react to chlorine at all and are relatively less responsive to OH radical, thus the UV/chlorine process can be the alternative treatment option. In this study, the degradation of IPM during UV-LED/chlorine processes were investigated by using three different UV-LED wavelengths. The fluence-based rate constant of UV-LED/chlorine increased about 20, 60 times at 265 nm, 310 nm respectively, and more than 70 times at 365 nm compared to UV photolysis, implying that combining UV-LED with chlorine showed a synergistic effect especially at higher wavelengths. The rate constant of IPM degradation decreased with increasing wavelength and the highest at pH 7 at 265 nm, and decreased as increasing pH at 310 nm and 365 nm. Although the wall plug efficiency of UV-LED was only 1.3% (265 nm), 3.5% (310 nm), and 67.6% (365 nm), electrical energy per order (EEO) was 1~2, 9~14, 58~130 kWh/m/order, respectively. To examine the contribution of reactive chlorine species (RCS) and OH radical, we used nitrobenzene, benzoic acid and dimethoxybenzene as probe substances. The contribution of OH radical decreased in the order of 365 nm (15~37%), 310 nm (7~10%), and 265 nm (4~6%) while the contribution of RCS decreased as the wavelength increased. And we found that most of the RCS produced at all wavelengths are ClO radicals.

Degradation of iopromide during UV-LED/chlorine reaction: Radical contribution and effect of wavelength

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.