Electroactivation of peroxymonosulfate (PMS)-coupled electrocoagulation for degradation of iodinated contrast media and reduction of I-DBPs formation: Dual control and QSAR modeling.

Iodinated contrast medias (ICMs) can act as an iodine source to react with dissolved organic matter (DOM) in the chlorination process to form toxic iodinated disinfection byproducts (I-DBPs). In this study, a coupled process of electrically activated PMS and electrocoagulation (EO-PMS/EC) was constructed to simultaneously remove iopamidol (IPM) and DOM, which has a dual control effect on the formation of I-DBPs. This system achieved a 90.1 % degradation rate of IPM, as well as remarkable removal of DOM. Firstly, the effects of experimental conditions and water matrix on IPM degradation were investigated; O, HO, SO, O and Fe (IV) are the main contributors to IPM degradation. Moreover, the transformation pathways of IPM were inferred and most of the intermediates were less toxic compared to I-DBPs. The formation of I-DBPs was reduced by 82.7 % and was effectively inhibited in all three real water samples. Furthermore, the developed QSAR model illustrate that the degradation rate constants of ICMs are positively correlated with the values of their highest occupied molecular orbital energies and dipole moments. This study provided a more effective I-DBPs reduction strategy which reduced the environmental risk of I-DBPs to a certain extent.