Novel Insight on the Effect of the Monomer Concentration on thePolypiperazine-Amide Nanofiltration Membrane

The monomer concentration is a key factor affectingthe diffusion rate and reaction rate of the monomers anddetermines the physicochemical property of polyamide nano-filtration membranes. However, the mechanism of the monomerconcentration effect on the polyamide nanofiltration membraneremains unclear. The properties of nascent membranes fabricatedwith different monomer concentrations with afixed ratio presentedcompletely new results in the absence of heat treatment. The resultsreveal that the polyamide layer thickness increases linearly with themonomer concentration when the concentration is high. Thenanofiltration membranes prepared at a low concentration have alarger pore size and a lower cross-linking degree, which contributedto high water permeability. The optimal membrane presented ahigh pure water permeability of 36.1 L h-1m-2bar-1, with theNa2SO4rejection maintained at 98.4%. This work provides a novelinsight into the relationship between the properties of thenanofiltration membrane and monomer concentration.

Automated summary

The monomer concentration critically influences the performance of polyamide nanofiltration membranes, with higher concentrations leading to increased polyamide layer thickness and lower concentrations resulting in larger pore size and lower cross-linking degree, thereby enhancing water permeability.