Enhanced iodide removal from aqueous solutions using 3D-printed PLA scaffold coated with Cu/Cu₂O nanoparticles

In nuclear power plant accidents, radioactive iodine (¹²⁹I, ¹³¹I) can enter the environment, accumulate in the food chain, and pose significant health risks. We developed a novel scaffold using Cu/Cu₂O nanoparticles immobilized on a polylactic acid 3D-printed scaffold for efficient iodide removal. The PLA scaffold was fabricated using a fused deposition modeling 3D printer, then surface-modified for enhanced hydrophilicity and functionalized with carboxyl groups via hydrolysis and acrylic acid grafting. Cu/Cu₂O nanoparticles were immobilized on the modified surface. The adsorption capacity, determined using the Langmuir model, was 4.85 mg/g, and adsorption kinetics followed a pseudo-second-order model. The iodide removal mechanism was primarily driven by redox reactions between Cu(0), Cu(I) and iodide, leading to the formation of copper iodide (CuI), as confirmed by X-ray diffraction and Raman spectroscopy. Importantly, the Cu/Cu₂O scaffold exhibited excellent structural stability during adsorption, with minimal copper leaching (<0.08 mg/L). Characterization of the Cu/Cu₂O scaffold using scanning electron microscopy with energy-dispersive spectroscopy and X-ray photoelectron spectroscopy analysis supported these results. The scaffold demonstrated high selectivity for iodide ions even with competing anions. The scaffold maintained its effectiveness across a wide pH range, and continuous column tests separately confirmed its suitability for practical applications in environmental remediation and wastewater treatment systems. In summary, we successfully fabricated a 3D-printed Cu/Cu₂O-PLA scaffold, demonstrated its efficient iodide removal performance, and elucidated the underlying redox-driven adsorption mechanism.