Equilibrium and kinetic studies on the removal of NaCl from aqueous solutions by electrosorption on carbon nanotube electrodes

In this paper, we prepared carbon nanotube (CNT) electrodes with polytetrafluoroethylene (PTFE) as binders to adsorb NaCl from water. The electrodes were characterized using scanning electron micrograph (SEM), nitrogen adsorption and cyclic voltammetry. The adsorption/electrosorption rate and capacity of CNT electrodes with different bias potentials were measured, and the electrosorption isotherms and kinetics were also investigated. The results showed that electrosorption can effectively increase the adsorption capacity and rate of NaCl on CNT electrodes. The adsorption/electrosorption of NaCl on CNT electrodes followed Langmuir isotherms and the pseudo-first-order adsorption kinetics. The equilibrium adsorption capacity at 1.2 V was 9.35 mg/g, which was nearly eight times higher than that at 0 V. Compared with the adsorption rate at 0 V, the adsorption rate at 1.2 V was increased by 58.9%. The enhancement of capacity and rate may be due to the forming an electric double layer on the surface of CNT electrodes in the solution.