Ion Separation

Ion separation is where an electric field, an ion-selective interface, and a controlled flow channel meet — and where most of your stack's selectivity and energy cost are decided. This collection groups the two hardware layers you need to study and run electro-driven separations on the bench: the polymer films that carry the selective transport, and the fixtures that hold them under reproducible flow. Together they cover electrodialysis (ED), electrodeionization (EDI), capacitive deionization (CDI and FCDI), bipolar-membrane electrodialysis (EDBM), and reactive CO2 capture coupled to electroreduction.

• Membranes — cation-exchange membranes (CEMs) with fixed sulfonate groups, anion-exchange membranes (AEMs) with quaternary-ammonium groups, and bipolar membranes (BPMs) that dissociate water at the CEL/AEL interface under reverse bias. Use these to set selectivity for desalination, acid concentration, and salt-splitting duty.
• Testing Cells — benchtop FCDI stacks, integrated reactive-capture cells, porous solid-electrolyte (PSE) reactors, and optically accessible flow electrolyzers. Use these to isolate the membrane-transport step from the rest of your process and quantify it under controlled flow.

The two layers are designed to be paired. The flow plates in the testing cells accept the same membrane chemistries listed here — PFSA and sulfonated-hydrocarbon CEMs, polyaromatic AEMs, and bipolar laminates — so you can swap films without re-tooling the fixture.

If you are screening salt removal or selectivity, start with the AEM and CEM grades and pair them with an FCDI or electrodialysis-style fixture. If you are generating acid and base on site, combine an acid-blocking AEM with a BPM in an EDBM stack. For ion-conducting membranes used in fuel cells, electrolyzers, and flow batteries instead, see Membranes and MEA.