Surface wettability guiding in situ cultivation engineering of hollow polymer nanospheres for persistent efficient uranium extraction

The development and manufacture of new materials that efficiently extract uranium from seawater and can be easily separated remains a challenge. Inspired by the bubbles generated at the solid interface, this work, for the first time, uses the wettability of the magnetized nanomaterial surface to regulate the growth of the nanobubble template. In this process, hollow polydopamine (PDA) nanospheres, which were functionalized by amidoxime (AO), were cultured. This material integrates hollow polymer nanospheres (HPNs) onto the surface of magnetic carbon nanotubes (m-CNTs) through a one-step in situ process, effectively overcoming the disadvantages of traditional cumbersome production and poor recyclability of HPNs, greatly improving the reusability of the material and reducing the cost, named m-CNTs@H-PDA-AO. The relationship between the surface wettability of CNTs and the morphology of in situ grown HPNs was investigated and a series of adsorption experiments show that m-CNTs@H-PDA-AO could reach a maximum adsorption capacity within 20 min in a 10 mL adsorption solution and within 50 h in a 50 mL adsorption solution, indicating rapid adsorption kinetics. The maximum adsorption capacity of m-CNTs@H-PDA-AO is 381.98 mg g−1 at 298 K. In a mixed solution containing coexisting ions, m-CNTs@H-PDA-AO has good selectivity for uranium and the highest removal efficiency reaches about 84.56%. Furthermore, the adsorption capacity of m-CNTs@H-PDA-AO towards uranium decreases slightly after five adsorption–desorption cycles, indicating good stability and reusability. In summary, this work offers a new approach for the construction of hollow materials using the nanobubble templating method and the development of new sorbents for uranium extraction from seawater with potential applications in high-level radioactive wastewater and other water bodies.