Selective removal of thorium ions from aqueous solutions using a hybrid mesoporous adsorbent as benzenesulfonamide-derivative@ZrO₂

Herein, we report a new sensitive and selective fluorescent probe of (Z)-4-((3-phenylnaphtho[1,2-b] furan-5-yl) diazenyl) benzenesulfonamide (PFBS) to detect thorium (Th(IV)) ions in aqueous solution. Moreover, direct grafting mesoporous zirconium oxide (ZrO₂) scaffold by PFBS-ligand was performed to prepare a hybrid ZrPFBS for selective removal of ultra-trace Th(IV) ions from aqueous solutions. Systematic investigations were done to adjust and optimize the factors impacting the Th(IV)-detection/adsorption process. The maximum Th(IV)-removal efficiency at pH 4 was 97.5 % using ZrPFBS adsorbent. To describe the Th(IV)-adsorption mechanism, the isotherm and kinetic investigations of Th(IV)-adsorption were studied. Langmuir and pseudo-second-order models successfully describe Th(IV) ion adsorption. Moreover, the optimized structure and separation energies of the PFBS and its proposed PFBS-Th(IV) complex were investigated using density functional theory (DFT) simulations. The results indicated that the proposed adsorption approach retained its ability to adsorb Th(IV) ions even after several reuse periods. The ZrPFBS adsorbent might be an effective and selective captor for Th(IV)-removal from water samples, particularly at low levels of thorium concentration.