Investigation of the effect of salts on dye wastewater separation performance in TpPa-1 membrane via molecular dynamics simulation

Abstract

The rapid progress in science and technology increases the demand for dyes and results in the pollution of dye wastewater. Recently, covalent organic frameworks (COFs) have been suggested as a promising candidate for wastewater treatment. The influence of inorganic salt ions on the transport and separation processes of dye wastewater is poorly understood. In this work, the transport and separation mechanisms of dyes are investigated via nonequilibrium molecular dynamics simulations (NEMD). It is found that the inorganic salts enhance the rejection rate of different dyes in TpPa-1 membranes. The fundamental reason for this phenomenon is the hindrance caused by inorganic salt ions, which change the orientation of dye molecules as they pass through the pore channels of the TpPa-1 membrane. As a result, the dye molecules show a greater tendency to form π–π interaction with the TpPa-1 membrane surface, which accelerates their adsorption.