Selective removal of uranium from an aqueous solution of mixed radionuclides of uranium, cesium, and strontium via a viable recyclable GO@chitosan based magnetic nanocomposite

Abstract

This work reports the performance study of a new magnetite@graphene oxide@chitosan nanoadsorbent synthesized by using magnetite, graphene oxide, and chitosan for selective adsorption of uranium(VI) ions from an aqueous solution containing salts of uranium, cesium, and strontium ions. Detailed analysis was done to get an insight into the structural features, elemental composition, surface micromorphology of the synthesized nanoadsorbent by using different techniques like Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDX), Scanning electron microscopy (SEM), and High-resolution transmission electron microscopy (HR-TEM). Initial studies revealed that magnetite@graphene oxide@chitosan nanoadsorbent proved to be an efficient adsorbent for removing uranium ions (84.39 %), cesium (7.17 %), and strontium (8.44 %) from an aqueous solution of mixed radionuclides. Several batch experiments were conducted by varying effective parameters such as adsorbent mass, pH, contact time, initial adsorbate concentration, and temperature to deduce the best conditions for maximum removal of uranium selectively from a mixed radionuclide aqueous solution. Maximum U(VI) adsorption capacity was 504 mg/g in 30 min at a pH of 6 and room temperature. For the as-prepared adsorbent, the equilibrium sorption and sorption rate closely matched the Langmuir model and was well fitted in a pseudo-second-order kinetic model. Thermodynamic parameters for the adsorbent (ΔH 22.06 KJ/mol, and ΔG˂0) show that U(VI) sorption is an endothermic and spontaneous process. Furthermore, cyclic adsorption-desorption studies show that the adsorbent can be used gainfully even after 10 cycles with only a minor decrease in its removal efficiency (97.50–90 %). Extraction studies using 15 mg initial adsorbent dose suggest that (42–34.75 ppm) of U(VI) can be recovered per cycle from a 50 ppm uranium solution. Conclusively this can be a viable method for removal extraction dual application for U(VI) from water.