Open-Source Ion Exchange Membrane

A homogeneous cation or anion exchange membrane you can make for under $1 per square foot using off-the-shelf materials: water softener resin, PVC or CPVC, and common solvents. No sulfonation, no specialty suppliers, no industrial equipment. Released under CERN-OHL-S 2.0, a strong reciprocal open hardware license.

Developed by Rowow LLC as part of SEM TECH, an open-source electrochemical platform for critical mineral recovery, acid regeneration, and metal refining.

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Why It Matters

Commercial ion exchange membranes cost roughly $100 per sheet, which locks small labs, startups, and researchers out of membrane electrochemistry. This recipe drops that cost by about two orders of magnitude and works in harsh conditions: pH 0 solutions, high oxidizing potentials, months of exposure.

Applications include precious metal and rare earth recovery, redox flow batteries, electrodialysis, acid and base generation, water treatment, and electroplating.

How It Works

Commercial ion exchange resin beads are already functionalized. The trick is mechanical: pulverize the beads into fine powder, disperse the powder in PVC or CPVC dissolved in a solvent such as THF, cast the mixture as a film, and dry. The result is a homogeneous membrane with resin functionality distributed through a chemically durable matrix that bonds directly to PVC cell bodies with ordinary pipe cement.

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