Performance and mechanism of U(VI) removal from solution by pomegranate peel carbon supported CaTiO₃ composites

In order to achieve the goal of green and efficient energy utilization, how to deal with uranium-containing waste generated during the development of nuclear energy has become an increasingly prominent environmental problem. The CaTiO₃ materials were initially prepared using the solvent-thermal method. Subsequently, the carbon material was synthesized by grinding a mixture of CaTiO₃ and pomegranate peel carbon material, resulting in the formation of carbon-loaded CaTiO₃ (C@CaTiO₃). Modern characterization techniques were employed to analyze the morphological and compositional changes of C@CaTiO₃ before and after its reaction with U(VI). The performance of the material in removing uranium from the solution was evaluated using a static experimental method. The research findings revealed that, under the conditions of pH=3.5, an initial concentration of U(VI) of 25 mg·L⁻¹, reaction time of 40 min, and temperature of 25℃, the material exhibited a U(VI) removal rate of 96.26% with a corresponding removal capacity of 119.21 mg·g⁻¹. The reaction mechanism between C@CaTiO₃ and U(VI) was investigated using adsorption kinetics models, isothermal adsorption models, and thermodynamic models. The results demonstrate that the adsorption process of U(VI) by C@CaTiO₃ is a spontaneous endothermic reaction. The removal of U(VI) from the solution using C@CaTiO₃ involved both adsorption and reduction, with physical and chemical adsorption coexisting and surface monolayer chemical adsorption being the predominant mechanism. Photocatalytic reduction played a major role in the reduction process.