Graphene oxide (GO) and zinc oxide (ZnO) were synthesized via the Tour’ and sol-gel methods, respectively. Adsorption potentials of Th(IV) ions were investigated with the functionalization of GO with ZnO nanoparticles (GO-ZnO) and compared with the GO. Studies concerning factors affecting the adsorption process, kinetics, adsorption isotherms, and thermodynamic properties were carried out. In this study, the optimum pH for the adsorption of Th(IV) ions is 3.0, and quickly reaching equilibrium is an indication of the high efficacy of the sorbent. A pseudo-second order adsorption model fits the kinetic data well. Experimental results were compared with Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models. These results show that the Langmuir model fits the data well. Measured thermodynamic parameters, Gibbs free energy change (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) indicate that the adsorption of Th(IV) on GO−ZnO is spontaneous and endothermic in nature. According to the linear fit in the Langmuir isotherm model, the maximum adsorption capacity of GO and GO-ZnO at 298 K occurs at 109.89 mg/g and 243.90 mg/g, respectively. The results show that decoration with ZnO nanoparticles is a good method to improve the adsorption capacity of GO for Th(IV) removal.

This study examines the removal of Th(IV) ions from aqueous solutions using reduced graphene oxide-zinc oxide (rGO-ZnO) nanofibers synthesized via electrospinning. The nanofibers were characterized using XRD, SEM, FTIR, XPS, and zeta potential measurements. Response surface methodology optimized adsorption parameters, including pH, temperature, Th(IV) concentration, and adsorbent dosage. The Freundlich isotherm indicated heterogeneous adsorption, and thermodynamic analysis revealed an endothermic process with enhanced efficiency at higher temperatures. The maximum adsorption capacity was 99.73 mg/g, demonstrating the high performance of rGO-ZnO nanofibers. Competitive adsorption studies demonstrated high selectivity for Th(IV), demonstrating the potential of rGO-ZnO nanofibers for radioactive wastewater treatment.