Flexible self-supporting electrode for high removal performance of arsenic by capacitive deionization

Capacitive deionization (CDI) technology has promising applications for the removal of arsenic from micro polluted water. The selection of electrode materials and the fabrication of electrodes are the core parts of the CDI technology. In this paper, the structure of graphene was modulated by inserting carbon quantum dots to form three-dimensional (3-D) rGO/NCDs electrode material and electrospinning method was applied to fabricate monolithic mesh self-supporting electrodes with excellent electrochemical and structure properties. In the experiments of arsenic removal, the rGO/NCDs electrode achieved an electrosorption capacity of 15.07 mg g-1 at 1.0 V, increasing by 29.5% compared with that of rGO electrode. In addition, the model fitting analysis of the experimental data showed that arsenic removal was consistent with pseudo-first-order kinetic model and Langmuir adsorption isotherm. The thermodynamic model suggested that electrosorption was a spontaneous exothermic process. The intraparticle diffusion model further revealed the diffusion mechanism of arsenic removal by CDI electrodes. In conclusion, the prepared flexible self-supporting rGO/NCDs electrode with high electrosorption capacity provided a new idea for the electrode preparation process and further promoted the large-scale application of CDI technology.