Ionic liquid - melamine foam composites for capture of thorium under high acidity conditions

Thorium has received much attention for potential application as nuclear fuel, but its capture at high acidity still requires more research. Ionic liquids (ILs) have been used to capture and separate various metal elements, but ionic liquid-containing composites have little been studied for thorium separation under high acidity conditions. A novel ionic liquid-foam composite (SIL-M) was prepared by loading stimuli-responsive ionic liquid (SIL) onto melamine foam (MF), and applied to separate thorium under high acid conditions. Under experimental conditions, SIL-M showed maximum adsorption capacity for thorium was 269 mg g−1 with an excellent selectivity for thorium over transition metals and lanthanide metals in 1 M HNO3 (S > 2 × 103). Studies revealed that PO was complexed with thorium, which also explained the high adsorption capacity and selectivity of SIL-M for thorium under high acidity within 4 cycles. Theoretical calculations were used to reveal that the reason why SIL can maintain high separation efficiency of thorium under high acidity conditions is due to the electrostatic potential of SIL is more positive. This study explored the possibility of using ionic liquid composite materials to capture thorium under strong HNO3 media, and provided ideas for designing thorium capture materials under high acidity conditions.