Cuttlebone-inspired PMIA Membranes with Symmetric Porous Structure for Enhanced Mechanical Stability of Ultrafiltration

Abstract

Tight ultrafiltration (TUF) membranes have garnered significant attention for the treatment of printing and dyeing wastewater, owing to their high separation efficiency and water permeance. However, macrovoids in TUF membranes fabricated via conventional non-solvent induced phase separation (NIPS) inherently undergo collapse-induced structural degradation under pressurization, markedly reducing water permeability. In this study, we develop a cuttlebone-inspired poly (m-phenylene isophthalamide) (PMIA) TUF membrane featuring a symmetric porous structure to effectively enhance stability of ultrafiltration. The resulting membrane fabricated through a double-sided NIPS process using a continuous microfluidic approach (M-PMIA) demonstrates superior structural robustness compared to conventionally cast PMIA membranes. The M-PMIA membrane achieves superior flux stability for 172 h continuous ultrafiltration with an exceeding rejection rate for Congo Red and demonstrates a high pure water permeance of 180 L·m-2·h-1·bar-1. Furthermore, the membrane exhibits excellent thermal and chemical stability throughout dye removal processes. This work proposes a promising approach for designing high-performance TUF membranes that facilitate efficient and stable purification of printing and dyeing wastewater.