Effect of gamma radiation on pyromellitic acid (PMA) and [formula omitted] solutions

Abstract

Abstract. In order to develop gamma radiation-induced polymeric materials for selective extraction of uranyl ions, functional stability (decarboxylation) of pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid) (PMA) exposed to different radiation dose was evaluated. In addition, decarboxylation of the compound was evaluated when carboxyl groups of the PMA are coordinated to uranyl ions. PMA and UO 2 2 + − PMA aqueous solutions in equimolar concentrations were irradiated up to 100 kGy absorbed dose with a Gammabeam 651 PT (60Co) irradiator at 13 kGy/h dose rate. Decarboxylation percentage was evaluated through potentiometric titrations before and after irradiation, and product characterization through infrared spectroscopy (FTIR) and proton magnetic resonance (1H-NMR). Results showed that PMA maintains its structure until 20 kGy absorbed dose, when decarboxylation and ring opening reactions begin, and showed that uranyl coordinated carboxylic groups of the PMA have greater resistance to decarboxylation compared to non-coordinated PMA (80% less at 50 kGy). Therefore, due to its resistance to gamma radiation-induced decarboxylation reactions when carboxyl groups are coordinated with uranyl ions, pyromellitic acid could be a viable candidate as a base compound for the development of ionic-imprinted materials for the selective extraction of uranyl ions in aqueous matrices.