Magnetic CNT-based electrode for efficient electro-adsorption of uranium.

Various magnetic carbon materials have been employed for nuclide adsorption, yet there exists a research gap concerning their application in electro-adsorption for nuclide removal. In this study, a magnetic carbon nanotube nanocomposite (Fe 3 O 4 /CNT) was successfully synthesized as an electrode material through the hydrothermal method, involving the modification of minute Fe 3 O 4 nanoparticles onto the surface of carbon nanotubes (CNT). Electrochemical assessments revealed that the Fe 3 O 4 /CNT nanocomposite exhibited a higher specific capacitance compared to Fe 3 O 4 and CNT individually. The HRTEM image reveals a heterojunction structure formed directly between Fe 3 O 4 and CNT, which facilitates electron transmission. The Fe 3 O 4 /CNT nanocomposite was utilized as an electrode in a capacitive deionization (CDI) device for U (VI)-contaminated wastewater purification. Experimental results demonstrated that the maximum U (VI) adsorption capacity of the Fe 3 O 4 /CNT electrode reached 287.53 mg/g at 298 K, and the adsorption process conformed to the Langmuir isotherm model. Kinetic analysis further indicated that the adsorption of U (VI) by Fe 3 O 4 /CNT followed a pseudo-second-order kinetic model. Additionally, the Fe 3 O 4 /CNT nanocomposite was transformed into a flowable electrode liquid and applied in a flow-electrode capacitive deionization (FCDI) system for U (VI) removal from aqueous solutions. Leveraging its superparamagnetic properties, the Fe 3 O 4 /CNT flow-electrode within the FCDI system could be rapidly recovered via a straightforward magnetic separation procedure. Notably, after nine consecutive runs of the FCDI device, the Fe 3 O 4 /CNT flow-electrode successfully concentrated a low-concentration U (VI) solution of 120 mg/L into a high-concentration solution of 1230 mg/L, thereby achieving the goal of water resource conservation and reduced storage requirements. [Display omitted] • The high-performance Fe 3 O 4 /CNT nanocomposite was prepared through a one-pot method. • The Fe 3 O 4 /CNT has a higher specific capacitance because of the synergistic effect. • The Fe 3 O 4 /CNT can be used as an electrode for CDI and FCDI devices to remove U (VI). • The Fe 3 O 4 /CNT flow-electrode can be quickly recovered by magnetic separation. [ABSTRACT FROM AUTHOR]