Synthesis of carbon-coated magnetic nanocomposites and its application for recycling of uranium-containing wastewater

Abstract

It is very important to properly treat uranium-containing wastewater scattered in the environment. In this study, we used the hydrothermal method to synthesize carbon-coated magnetic Fe₃O₄ nanoparticles and then modified by sodium hydroxide to yield magnetic carbon nanomaterials (Fe₃O₄@HTC-NaOH). The microstructure and chemistry of the material were characterized by TEM and FTIR. We investigated the adsorption behavior of materials for uranium (VI) under different conditions, including pH, contact time, initial uranium concentration, and temperature. The results indicated that this material adsorbs uranium quickly, achieving equilibrium in static adsorption after approximately 225 min. The adsorption behavior was strongly dependent on pH, and the maximum adsorption capacity (457.83 mg/g) was reached at pH 5.5. The initial concentration also had a role in the adsorption behavior. With the gradual increase of the initial concentration of uranium (VI), the adsorption capacity showed an increasing trend and reached saturation at 100 mg/g. Adsorption isotherm could be well fitted by the Langmuir model and the pseudo-second-order kinetic model. And the results indicated it is a heat-absorbing reaction. Owing to the introduction of Fe₃O₄, the material is magnetic and the solid-liquid separation can be rapidly completed by the pairing of magnets. The new material could be regenerated using HNO₃, and the adsorption rate could maintain above 75% after five adsorption/regeneration cycles, which illustrated its certain practical application value.