A Marine-Inspired Hybrid Sponge for Highly Efficient Uranium Extraction from Seawater

Marine sponges are used as biomonitors of heavy metals contamination in coastal environment as they process large amounts of water and have a high capacity for accumulating heavy metals. Here, inspired by the unique physical and physiological features of marine sponges, a surface engineered synthetic sponge for the highly efficient harvesting of uranium from natural seawater is developed. An ultrathin poly(imide dioxime) (PIDO)/alginate (Alg) interpenetrating polymer network hydrogel layer is uniformly wrapped around the skeleton of a melamine sponge (MS) substrate through a simple dipping-drying-crosslinking process, providing the hybrid MS@PIDO/Alg sponge with excellent uranium adsorption performance and sufficient mechanical strength to withstand the harsh conditions of practical applications. The maximum adsorption capacity reaches 910.98 mg-U g-gel(-1) for the PIDO/Alg hydrogel layer and 291.51 mg-U g-sponge(-1) for the whole hybrid MS@PIDO/Alg sponge in uranium-spiked natural seawater. The adsorption capacity measured after 56 d of exposure in 5 tons of natural seawater is evaluated to be 5.84 mg-U g-gel(-1) (1.87 mg-U g-sponge(-1)). This novel approach shows great promise for the mass production of high-performance sponge adsorbent for uranium recovery from natural seawater and nuclear waste.