Molecular dynamics simulations of water desalination through polymerized fullerite membrane

A water-filtering architecture based on nanoporous membranes is proposed for water desalination. In this paper, we show via molecular dynamics simulations, a polymerized fullerite membrane enables an outstanding water permeability with perfect salt ion rejection. Compared to the conventional reverse osmosis and nanoporous graphene, the water permeability is found to be much higher. A collective motion of hoping single-file water through a nanopore, which is tuned through desalination velocity and temperature, is identified and proved to be of great significance in enhancing water permeability. Single-file water with concerted dipole orientation exhibits faster water permeation through nanopores of polymerized fullerite membrane. It is revealed that larger desalination velocity will bring defects to the dipole orientation of single-file water, resulting in water reorientation through nanopores and lower water permeability. The polymerized fullerite membrane is found to suffer from bending deformation at high hydraulic pressure, leading to pore enlargement and degradation of salt rejection. An optimization scheme is provided to ensure a sustainable desalination performance. These insights shed light on polymerized fullerite as a prospective membrane for water purification and provide theoretical guidelines for achieving fast water permeation through collection motion of single-file water.