Understanding the Water Permeability and Cu2+ Removal Capability of Two-Dimensional Nanoporous Boron Nitride

The discharge of Cu2+ from industrial wastewater to nature will pose a serious threat to human health. In order to separate Cu2+ from sewage, the copper removal process with hexagonal boron nitride (h-BN) membrane is studied using molecular dynamics simulations. The relationship between water flux and pore size, pore chemistry and external pressure is analyzed in detail, and the filtration mechanism of Cu2+ is also discussed. The results show that water flux is proportional to the pore size and external pressure. The water flux across the membrane with N-edged pore is larger. There is a potential barrier for Cu2+ with the membrane of B-edged pore, which is beneficial to the separation of Cu2+. When the radius of the pore is smaller than the second hydration radius of Cu2+, Cu2+ removal capability is better. In particular, nanoporous h-BN membrane with B5 pores has several orders of magnitude higher water permeability and 1–2 orders of magnitude lower energy consumption than traditional reverse osmosis membranes. Overall, this work has a guiding role in the liquid phase separation of heavy metal ions.