Role of the intrinsic properties of partially reduced graphene oxides on the chemical transformation of iopromide

The role of the intrinsic properties of graphene oxide (GO) and partially reduced graphene oxide (rGO), and their use as redox mediator (RM) is reported, for the first time, on the chemical transformation of iopromide (IOP), an iodinated X-ray contrast medium, under anaerobic conditions. The structural and physicochemical properties of GO containing different types of oxygenated groups, were analyzed by Boehm titrations, point of zero charge (pHPZC), pKa's distribution, scanning electron microscopy (SEM), electrochemical analysis, as well as by Raman, Fourier transform infrared and UV-Vis spectroscopy. Complete characterization of GO-based materials revealed the removal of different oxygenated groups, such as epoxy and hydroxyl groups, and a transition from an amorphous to a more crystalline structure on partially reduced GO. Moreover, when rGO materials were tested as RM, they promoted a faster and greater extent of IOP transformation up to 5.2-fold with sulfide as electron donor. Results showed a correlation between the reduction degree of GO and its ability to act as RM, which was reflected in the dehalogenation and transformation degree of IOP. Additionally, the chemical transformation pathway of IOP is proposed based on HPLC-MS analysis.