A chitosan film implanted with g-C₃N₄@Ag nanosheets and in-suit formed AgCl nanoparticles for efficient iodide removal

Radioactive iodine is one of the main environmental pollutions in nuclear waste, which can cause severe health issues. Highly flexible and crosslinked chitosan film embedded with g-C₃N₄@Ag (CN@Ag) nanosheets, and in-suit formed AgCl nanoparticles was prepared as an efficient adsorbent for removing iodide ions (I⁻) in nuclear wastewater through multiple interactions mechanisms. The adsorption performance of the composite film for ¹²⁷I anions (to mimic the radioactive iodine) was investigated in detail, including adsorbent dosage, pH, co-existing anions, and adsorption kinetics/thermodynamics, etc. The adsorbent maintains a high I⁻ removal efficiency (∼90%) over a wide range of pH (3–11). The adsorption isotherm fits well with the Freundlich equation while the kinetics follow the pseudo-2nd order rate model. The I⁻ adsorption capacity reached ∼ 1.12 mmol/g, more than doubled that of crosslinked pristine chitosan film. The adsorption mechanism was found to consist of physisorption, chemisorption, and chemical reaction. The composite film also showed reasonably good recyclability, thus presenting a promising adsorbent for iodide removal from nuclear wastewater.