Perfluorinated Cation-Exchange Membrane (CEM) for Chlorine Dioxide and Chlorine Alkali Reactor, CCDCARPCEM

Perfluorinated cation-exchange membranes (CEMs)—such as perfluorosulfonic acid (PFSA) and perfluorocarboxylic acid (PFCA) composite films (widely known under commercial designations like Nafion, Flemion, or equivalent industrial grades)—represent the gold-standard separator technology for severe industrial electrochemical environments like chlor-alkali cells and electrochemical chlorine dioxide (ClO2) reactors.

High-performance perfluorinated membranes engineered for chlor-alkali and aggressive halogen reactors typically utilize sophisticated composite structures: (1) Reinforced Mechanical Substrate: Many industrial grades incorporate an embedded expanded polytetrafluoroethylene (ePTFE) fibril mesh reinforcement to eliminate membrane stretching, creep, and dimensional deformation under high differential pressures and fluid velocity. (2) Anode-Facing PFSA Layer: A thicker primary layer featuring sulfonic acid groups, optimized for high ionic conductivity, low voltage drop, and stable operation in acidic-to-neutral, chlorine-saturated brine feeds. (3) Cathode-Facing PFCA Layer: A thin surface layer featuring carboxylic acid groups facing the high-concentration caustic compartment. Carboxylic groups exhibit a much higher electrostatic repulsion barrier against migrating hydroxyl (OH-) ions, preventing back-migration and enabling direct production of high-purity caustic soda (typically 32% to 35% NaOH).

Reference: 

1. H. Tang, et al., Anion conductivity of cation exchange membranes in aqueous supporting electrolytes, Solid State Ionics, 2022, 383, 115984
2. Y. Liu, et al., Journey of electrochemical chlorine production: From brine to seawater, Current Opinion in Electrochemistry, 2023, 37, 101202