Chemically Stable and Porous Bi ₂ S ₃ /Mg(OH) ₂ Nanocomposite for Highly Efficient Adsorption of Radioactive Iodide

Water contamination by radioactive iodide (I–) presents significant environmental and public health risks. In this study, a chalcogenide-based hydroxide nanocomposite (Bi2S3/Mg(OH)2) was developed as an efficient adsorbent for (I–) removal. FE-SEM analysis revealed that Bi2S3 nanoparticles were uniformly anchored on Mg(OH)2 polyhedral surfaces, increasing the surface area to 22.154 m2/g. XPS confirmed the presence of Bi3+, S2–, Mg2+, and I 3d states after adsorption. EDX analysis showed an even element distribution. The inclusion of Mg(OH)2 improved the iodide adsorption capacity (qe) from 171.27 to 203.61 mg/g at neutral pH. The adsorption process followed pseudo-second-order kinetics, as indicated by the correlation coefficient R2 ≥ 0.99, with Langmuir maximum capacities (qmax) of 175.063, 202.584, and 239.786 mg/g for Bi2S3, Mg(OH)2, and the nanocomposite, respectively. Thermodynamic studies revealed that the adsorption process was spontaneous and exothermic. Reusability tests confirmed a high adsorption efficiency even after five regeneration cycles. The nanocomposite presents a promising adsorbent material for the treatment of iodide-contaminated water.