FAQ

The Membrane

What is it made from? Pulverized commercial ion exchange resin (the kind used in water softeners) dispersed in a PVC or CPVC binder, cast from solvent into a film. Cation resin makes a cation exchange membrane; anion resin makes an anion exchange membrane.

Why is it so cheap? The resin is already functionalized, so the expensive chemistry (sulfonation or amination of a polymer backbone) is skipped entirely. The rest is commodity plastic and solvent. Under $1 per square foot versus roughly $100 per sheet commercially.

How durable is it? Testing in acidic and alkaline mining solutions at high oxidizing potential has shown durability over months of exposure. PVC and CPVC are chemically resistant matrices, and the membrane is watertight when properly cast.

Cation vs anion membrane? A cation exchange membrane passes positive ions and blocks negative ones. An anion exchange membrane does the opposite. Cell designs use one or both to control where ions go.

Can I buy one instead of making it? Yes, membranes and cells are available at rowow.net when in stock.

Can it produce acids and bases? Yes, membrane electrolysis can split salts into acid and base streams, related to industrial chlor-alkali chemistry. This generates hazardous gases; only do it with proper ventilation and monitoring.

SEM TECH

What is SEM TECH? Salt Electro Mining Technology: an open-source electrochemical platform that uses saltwater chemistry, electricity, and these membranes to extract, separate, and refine metals from ores, e-waste, tailings, and waste streams, with in-situ acid regeneration in a closed loop.

Does it actually work? Proof of function is demonstrated publicly at lab and prototype scale, including a working divided cell and processing of real mining materials. See the Proof of Function video. Development toward pilot scale is ongoing.

Can it process e-waste? Yes, e-waste is a major target application: copper, gold, silver, palladium, nickel, tin, and rare earths from circuit boards and scrap.

Can it clean contaminated water or tailings? Environmental remediation is one of the most promising applications: extracting heavy metals from contaminated material instead of just burying it. Performance depends on the specific contaminant profile and site.

Can I run it at hobby scale? The components are accessible and the system scales down, but this is not casual chemistry. Even small cells produce chlorine and hydrogen. Read the Safety page first.

Contributing

I built one. What now? Report your build. Working or not, the data helps.

Can I use this commercially? Yes. CERN-OHL-S means no rights reserved, no permission needed, commercial use included.