Development of C/Ag nanocomposites for adsorption and immobilization of iodine-131 (131I) from the urine of thyroid ablation therapy patients

Iodine-131 (131I), a widely used radionuclide for thyroid cancer therapy, can present in a liquid waste that poses significant environmental risks if not properly managed. This study aims to develop carbon/silver (C/Ag) nanocomposites optimized for the adsorption and immobilization of 131I in urine waste from post-thyroid cancer therapy patients. The carbon precursor was derived from palm kernel shells (PKS), and chemically modified using gamma irradiation to enhance its properties. The C/Ag nanocomposites were synthesized via the incipient wetness impregnation method to improve their affinity for 131I. Characterizations were conducted using FESEM-EDS, XRD, FTIR, TGA, DSC, and N2-sorption analyses to confirm the structural and surface properties of the material. Adsorption tests revealed a maximum adsorption uptake (Cµmax) of 1543 MBq/g at pH 3 for the C/Ag-treated irradiation nanocomposite in 131I solutions which was well fitted with the Langmuir adsorption model. The adsorption kinetics were well described by a pseudo-second order (PSO) model, with a rate constant of 3.56 × 10−4 MBq/g.min−1, demonstrating a rapid adsorption performance. Under simulated urine waste conditions, the nanocomposite exhibited an excellent stability with a Cµmax of 1212 MBq/g at pH 5.5, also following the Langmuir model. The adsorption kinetics under these conditions were similarly described by the PSO model, with a rate constant of 2.84 × 10−4 MBq/g.min−1. Therefore, the C/Ag nanocomposites are promising materials for the efficient management of 131I waste in nuclear medicine facilities.