ELECTROCHEMICAL METHODS FOR THE SUSTAINABLE RECOVERY OF GADOLINIUM FROM MRI CONTRAST AGENTS AND FOR THE FABRICATION OF GADOLINIUM-RICH NANOPARTICLES.

The widespread use of gadolinium-based contrast agents (GBCAs) in magnetic resonance imaging (MRI) has led to increasing concern over the release of gadolinium into the environment. Gadolinium (Gd) is excreted in complexed forms that are stable and difficult to remove through conventional wastewater treatments, posing both environmental and health-related risks. To address this issue, this work explores two electrochemical strategies aimed at the sustainable recovery and reuse of Gd: a degradation method for GBCAs in various matrices, and the synthesis of Gd-containing nanoparticles starting from GBCA model compounds. In the first approach, electrochemical tests were carried out on different matrices containing GBCAs, including production wastewater and artificial urine. Good results were obtained across various conditions, supporting the versatility and applicability of the method. The process enabled Gd recovery from solution while reducing the chemical oxygen demand (COD) of the matrix. This dual effect highlights the potential of electrochemical treatments not only to recover valuable metals, but also to improve the overall quality of the treated wastewater. The second part of the study focused on the synthesis of Gd-containing zinc hexacyanoferrate nanoparticles through an electrochemical process. Gd³⁺ ions were successfully incorporated into the particles and are likely retained near their surface, potentially enhancing interaction with water molecules, a key feature for MRI applications. These nanoparticles could represent a promising alternative to conventional GBCAs, with the possibility of tuning gadolinium content to achieve high contrast efficiency. However, further studies are needed to assess their biocompatibility and actual performance as contrast agents. Overall, the two approaches offer complementary solutions for the management of GBCA-related waste: one aiming at direct Gd recovery from wastewater, and the other enabling the transformation of Gd into functional nanomaterials. Both contribute to mitigating environmental impact while promoting a circular approach to critical raw materials.