Ion Exchange-Based Microreactors Harness Self-Generated pH Gradients and Long-Range Flow for Dual-Enhanced Uranium Extraction

Radioactive uranium presents a significant threat to human health and the aquatic ecosystem. Therefore, uranium extraction technologies with high efficiency, environmental friendliness, and high selectivity are highly required, but remain challenging. In this work, a microreactor based on cation-exchange reaction (CIEX) is designed for dual-enhanced uranium extraction. The microreactor with local pH regulation, self-generated long-range flow, abundant functional groups, and the photoreduction greatly enhances the transport of uranium toward the adsorbent, as well as the adsorption of binding sites by breaking the adsorption–desorption equilibrium in an energy-saving and environmentally friendly manner. Benefited from the above, a significant uranium removal capacity of 1556 ± 44.5 mg g⁻¹ is reached within 120 min in 30 mg L⁻¹ uranium solution. Meanwhile, the microreactor shows high selectivity toward uranium among other cations, applicability in various non-marine waters, and good recyclability. This work proposes a unique methodology for autonomous uranium removal with minimized secondary pollution.