Calcium carbonate/ε-poly(lysine) hybrid microparticles for uranium seawater extraction: an eco-compatible emergency response to marine nuclear disasters

During the past decade, a large variety of materials dedicated to uranium seawater extraction has been developed for harvesting purposes. Yet, materials especially designed for decontamination following nuclear accidents are scarce and eco-friendly ones even rarer. In this study, hybrid microparticles made of biocompatible calcium carbonate and ε-poly(lysine) are used as efficient U sorbent in seawater. Their eco-friendly nature makes them interesting for both harvesting and on-site immobilization of radionuclides, also accounting their ability to settle in the seabed with limited impact on eco-systems. The material shows excellent U extraction capability in contaminated seawater ([U] = 10 ppm) with removal rate R of 87.7 % and extraction capacity of 513 mg per g of ε-poly(lysine) and remains efficient in natural condition ([U] = 2.8 ppb) with R = 39.8 %. In addition, the sorbent has a remarkable selectivity toward U versus V in U contaminated seawater as well as a significant affinity for Sr 2+ . DFT and XPS analyses revealed that U is adsorbed to ε-poly(lysine) via a chelation mechanism that involves amide and amine groups of lysine. Lability of the formed coordination complex allows easy recovery of captured U by contact with NaHCO 3 desorbing solution, ensuring recyclability of the material.