CO₂ Removal using Membranes

Preferred: CO₂ Removal by GTM Gas Transfer Membranes like 3M’s Liqui-Cel™

Water, even pure water, contains dissolved CO2 gas and the ionic bicarbonate form HCO3-. Dissolved CO2 gas can be removed using GTM membranes; this is a closed clean system. Ionic HCO3- can be removed using RO if the pH is right. Understanding the pH of the RO feed, the RO permeate, and how this affects choice of CO2-removal strategy is important.

For effective CO2 removal using Liqui-Cel, the CO2 should all be the “Dissolved CO2” gas, so the pH should be under about 6.5.

For effective CO2 removal using RO, the CO2 should be all carbonate (CO3-2) or bicarbonate (HCO3-), so the pH should be above about 7.5. pH for 2-pass RO with interstage caustic: the 2nd stage should be ideally pH 8.4-8.7 for best results.

• SnowPure partners with 3M Liqui-Cel to provide GTM for high purity water
• CO₂ Removal by Liqui-Cel-Tech Brief
• RO-EDI Combined with Liqui-Cel-Tech Brief
• Liqui-Cel Improves EDI Performance Tech Brief
• How to Measure CO2 and HCO3 in RO Permeate
• 3M Liqui-Cel Website: http://www.liquicel.com

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3M Liqui-Cel^tm Membrane Contactors are used for degasing liquids around the world. They are widely used for CO2 removal from water. GTM is a clean technology that has displaced the vacuum tower and open air forced draft deaerator over the past 20 years.

3M Liqui-Cel^tm Membrane is used extensively for deaeration of liquids in power generation, microelectronics, pharmaceutical, and industrial markets just to name a few.