Acid-Resistant triazine-amine-based Polyamide-Sulfonamide nanofiltration membranes for efficient acidic wastewater treatment

Abstract

The discharge of acidic wastewater poses a significant environmental challenge to sustainable industrial development, underscoring the urgent need for advanced technologies capable of efficient water and acid resource recovery. Nanofiltration (NF) as a promising approach, yet the high-performance acid-resistant membrane is still in great demand. Herein, an acid-resistant NF membrane is designed and prepared by generating sulfonamide groups from the large-size triazine amine monomer and 1,3,6-naphthalene trisulfonyl trichloride (NTSC). Specifically, the acid-resistant nanofiltration membrane was fabricated via interfacial polymerization using the synthesized N²,N⁴,N⁶-tris(2-aminoethyl)-1,3,5-triazine-2,4,6-triamine (TET) with NTSC and 1,3,5-benzenetricarbonyl trichloride (TMC). Owing to the reduced density of amide bonds in the separation layer caused by the increased spatial dimensions of the TET monomer and the formation of sulfonamide structures, the resulting membrane demonstrated high stability under harsh acidic condition, maintaining 97.3 % of rejection for Na₂SO₄ along with 4.87 LMH·bar⁻¹ of water permeability, even after prolonged exposure to 15 % H₂SO₄ for 80 days. This work introduces a novel strategy to enhance the membrane stability in acid environment, offering a promising candidate for practical applications in acidic wastewater treatment.