Structurally Robust 3D-Printed ZIF-8 Monoliths for Efficient and Recyclable Iodine Removal from Water

The efficient removal of radioactive iodine from aqueous nuclear waste is hindered by its high mobility and water solubility. Here, robust three-dimensional (3D) printed ZIF-8 monoliths were fabricated via a direct ink writing strategy and evaluated for aqueous iodine removal. A highly loaded printable ink containing up to 80 wt% ZIF-8 was formulated using carboxymethyl cellulose and kaolin, enabling the construction of mechanically stable monoliths with interconnected macroporous channels, while the intrinsic microporosity and crystallinity of ZIF-8 were well preserved. Static adsorption experiments using I 3 ‒ solutions showed a high iodine uptake capacity of 1.4 g g −1 at room temperature. Notably, the monolithic architecture significantly improved water stability and recyclability, retaining 83.8% of the initial removal efficiency after five adsorption–regeneration cycles, whereas ZIF-8 powders degraded rapidly and retained only 75.8% efficiency after two cycles. Dynamic column tests further demonstrated effective iodine removal under continuous flow conditions up to 1.5 mL min −1 . Structural analyses confirmed structural integrity after 3D printing and iodine adsorption, while elemental mapping revealed a homogeneous iodine distribution within the monolith. This work highlights 3D printing as an effective route to transform MOF powders into water-stable monolithic adsorbents for practical aqueous radioiodine remediation.