Efficient iodine capture by ethylene diamine grafted ZIF-11-NH2 metal-organic framework

Generating efficient and clean energy from nuclear power has attracted much attention. However, the improper disposal of radionuclides (especially ¹²⁹I and ¹³¹I), originating from nuclear fuel processes poses significant risks to the environment and human well-being. So, fabricating reliable sorbents to uptake radioactive wastes is an urgent need. ZIF-11 as a typical MOF (metal–organic framework), represents good potential for this purpose. In this study, to enhance the iodine capture performance of ZIF-11, amine-functionalized ZIF-11 (ZIF-11-NH₂) and ethylene diamine (EDA) grafted ZIF-11-NH₂ (EDA@ZIF-11-NH₂) were synthesized. The EDA@ZIF-11-NH₂ (4030 mg g⁻¹) and ZIF-11-NH₂ (2300 mg g⁻¹) exhibited higher adsorption efficiency compared to the pristine ZIF-11 (1050 mg g⁻¹). Various techniques are used to characterize the structure of fabricated compounds, such as FT-IR (Fourier-transform infrared) spectroscopy, PXRD (powder X-ray diffraction), field emission scanning electron microscopy (FESEM), and EDS (energy-dispersive X-ray spectroscopy) mapping. According to the SEM images, the ZIF-11 and ZIF-11-NH₂ have the same morphology. The EDA@ZIF-11-NH₂ was stable and recyclable during the uptake iodine process, indicating its potential as an outstanding sorbent material. The kinetic adsorption analysis demonstrated that the adsorption of iodine onto EDA@ZIF-11-NH₂ followed pseudo-second-order kinetics, indicating that chemisorption is the predominant mechanism governing the adsorption process.