The performance of a C2N membrane for heavy metal ions removal from water under external electric field

Using molecular dynamic simulations, the performance of carbon nitride (C₂N) was studied for the separation of Cu²⁺ and Hg²⁺ as heavy metal ions from water. The high porosity of the single layer C₂N nanosheet in comparison with other similar carbon-based membranes and the existence of nitrogen atoms at the edge of the pores increase the efficiency of C₂N for water purification. The separation of heavy metal ions through the nanosheet is performed by applying an external voltage across the membrane. Investigation of the ions permeation through the membrane demonstrates that the permeability of the Cu²⁺ ions through the C₂N is about 2.5 times higher than that of Hg²⁺. The results of radial pair distribution function analysis illustrate that the energy barrier for ions passage is due to the hydration shell of the cations. Also, the density of the cations and water molecules, and the hydrogen bonds between water molecules in the whole system are analysed for the study of the performance of C₂N nanosheet for ion separation and these results demonstrate that this membrane has the selectivity performance for heavy metal removal and higher permeability of the cations than that of other carbon-based membrane because of high porosity.