Detection and Selective Removal Strategy of Thorium Ions Using a Novel Fluorescent Ligand and Hybrid Mesoporous γ-Al₂O₃-like Nanoneedles

Long-term exposure to radioactive elements through water, such as thorium ions, has undesirable impacts and may cause serious health problems like cancer. Therefore, this manuscript originally targets detection and elimination of thorium ions from water samples, even at trace concentrations. Herein, a novel ligand, (Z)-N-carbamimidoyl-4-((3-phenylnaphtho[1,2-b]furan-5-yl)diazenyl)benzenesulfonamide (CFBS), was synthesized for fluorometric detection of thorium ions. Then, the prepared CFBS-ligand was well-immobilized and grafted with mesoporous γ-Al₂O₃-like nanoneedles to prepare a hybrid mesoporous γ-Al₂O₃-like nanoneedles (CFBS@AlNNs) adsorbent. The CFBS@AlNNs adsorbent was employed to adsorb and remove thorium ions from an aqueous solution. The results indicated that trace concentrations of thorium ions could be detected and removed with good sensitivity and selectivity. The findings confirmed superior adsorption efficiency (98%) and capacity (142 mg/g) of used CFBS@AINNs toward Th(IV) ions at pH 4. The mechanism of Th(IV)-adsorption was explained mathematically through kinetic studies, isotherm models, and computational studies. One of the key advantages of CFBS@AlNNs is its thorium selectivity even in the presence of other coexisting ions. The CFBS@AlNN design showed significant thorium-removal/adsorption capacity, although multiple reuse/recycling followed a simple desorption process. Given its high selectivity, fast diffusion, and highly efficient adsorption, the CFBS@AlNNs sorbent can be considered a potential adsorbent to remove and recover thorium ions from various water samples and can be used to prevent the health risks related to the long-term and direct exposition of thorium ions.