Atomistic insights into high-performance polyimine-based membranes for selective dye rejection and salt permeation in nanofiltration

Abstract

Conventional treatment methods are often ineffective in eliminating organic dyes, which are among the most frequently discharged pollutants in wastewater. The present work explored a polyimine-based membrane in the context of textile wastewater treatment. This study employs classical molecular dynamics simulations to evaluate the efficacy of polyimine membranes. A reliable atomistic model of the membrane was constructed using an equilibrated mixture of melamine and 1,3,5-triformylphloroglucinol monomers. Non-equilibrium molecular dynamics (NEMD) simulations were performed on the constructed membrane system to investigate the performance of the polyimine membrane in a nanofiltration (NF) process using a mixed feed of NaCl salt, dye, and water. We observed that the polyimine membrane demonstrates excellent water permeability, effectively rejects dye, and allows the passage of NaCl salt. The atomistic insights into membrane-salt ion interactions and membrane-dye interactions provided in this work can inspire further experimental investigations into poly-imine membranes for separating salts and dyes, particularly in the treatment of textile industry wastewater.