Separation of copper and mercury as heavy metals from aqueous solution using functionalized boron nitride nanosheets: A theoretical study

Molecular dynamics simulations were performed to investigate the separation of copper and mercury ions as heavy metals from aqueous solution through the functionalized pore of a boron nitride nanosheet (BNNS) membrane. The considered system was comprised of a BNNS with a functionalized pore located in the centre of a simulation box containing an aqueous ionic solution of copper chloride and mercuric chloride. An external voltage was applied along the simulated system in order to produce a separation of heavy metals using pore of BNNS. A functionalized pore of BNNS was obtained by passivating each nitrogen and boron atoms at the pore edge with a fluorine and hydrogen atom, respectively. Our results show that the voltage caused the Cu²⁺ and Hg²⁺ cations to pass selectively through the functionalized pore of the BNNS. This selective behaviour of the BNNS is due to the potential of the mean force of each ion. The potential of the mean force of the heavy metals shows that the heavy metals ions met an energy barrier and could not pass through the functionalized pores of the BNNS. By applying a voltage to the system, they overcame the energy barrier and crossed the pores. We calculated the radial distribution function of ion-water and its integrations; the ion retention time; the hydrogen bond; and the autocorrelation function of the hydrogen bond. Using these parameters, the structure of the water molecules and ions were investigated in the system.