(701a) Poly(homopiperazine-amide) Thin Film Composite Nanofiltration Membrane for Heavy Metal Ions Removal

The development of membrane-based technologies for the treatment of wastewater streams and resources containing heavy metal ions is at high demand. Among various technologies, nanofiltration (NF) membranes are attractive choices, and the continuous development of novel materials to improve the state-of-the-art NF membranes is highly desired. Here, we report on the synthesis of poly(homopiperazine-amide) thin-film composite (HTFC)-NF membranes, using homopiperazine (HP) as a monomer. The surface charge, hydrophilicity, morphology, crosslinking density, water permeation, solute rejection, and antifouling properties of the fabricated NF membranes were evaluated. The fabricated HTFC-NF membranes demonstrated water permeability of 7.0 + 0.3 L/m²h bar and rejected Na₂SO₄, MgSO_4, and NaCl with a rejection value of 97.0 + 0.6%, 97.4 + 0.5%, and 23.3 + 0.6%, respectively. The membranes exhibit high rejection values of 98.1 + 0.3% and 96.3 + 0.4% for Pb²⁺ and Cd²⁺ ions, respectively. The fouling experiment with humic acid followed by crossflow washing of the membranes indicates that a flux recovery ratio (FRR) of 96.9 + 0.4% can be obtained.