This work aimed at developing novel adsorbents to remove arsenic ions in an aqueous solution. To this end, the use of polymeric materials and functionalized nitrogen-doped carbon nanotubes (N-CNT) was considered to adsorb arsenic ions from aqueous solutions. In this regard, the effects of experimental parameters including pH, contact time, initial concentration of metal, and the adsorption temperature were studied. According to experiments, the optimum solution pH for arsenic adsorption at 20 °C was 7. As the contact time increased, the adsorption rate increased and reached equilibrium after 10 minutes. The arsenic adsorption capacity of Polyether Sulfone/N-CNT nanocomposites increased with increasing temperature. The highest adsorption capacity was achieved at 49 °C. The equilibrium data obtained in the initial concentration range of Arsenic and the studied temperature was consistent with the Freundlich isotherm. The adsorption kinetics revealed that the arsenic adsorption followed the Pseudo-First order and Weber Morris equation. The thermodynamic parameters (ΔH, ΔG, and ΔS) indicated that the arsenic adsorption in the temperature range of 332-296 K was spontaneous and endothermic. The adsorption properties of the modified N-doped carbon nanotubes towards arsenic ions were also studied by density functional theory (DFT) calculations.