• CO2 nanobubbles

    Capturing CO2

    Capturing CO2 in water using nanobubbles is a much more effective method than flushing water with CO2 gas

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    injecting CO2 gas


    Injection of CO2 gas (flow 1 L/min, normopressure, room temperature), generates bubbles that rise rapidly to the surface. This method has limited transfer efficiency, although the natural solubility of CO2 in water is much higher than of O2.


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    CO2 nanobubble generator

     With the nanobubble generator (CO2-flow 1 L/min, normopressure), transfer efficiency is much higher, only a small number of tiny bubbles escape to the surface. In fact, transfer of CO2 to water is even more efficient than transfer of O2: approx. 94%.


  • Verification of CO2 capture


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    Limewater test

     Samples of CO2-nanobubbles, at different circulation times in the nanobubble generator (1 L/min CO2, 50 L water), were mixed with a dilute aqueous solution of calcium hydroxide ("limewater") resulting in precipitation of calcium carbonate.


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    A fraction of CO2 that dissolves in water reacts to form carbonic acid, H2CO3. Carbonic acid is unstable and rapidly dissociates to form hydrogen ions and bicarbonate- and carbonate ions. Dissolving CO2 in water therefore results in acidification.

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    pH measurements

    pH measurements during capture of CO2 (flow 1 L/min) by circulation in our nanobubble generator (50 L tapwater, temperature 20.3-26.3oC). Starting pH of tapwater is 8. Increasing accumulation of CO2 results in lowered pH (acidification).


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    Estimation of dissolved CO2

    Since the alkalinity of our tapwater is known (KH 7,97 mEq/L), the concentration of free dissolved CO2 in water during circulation in the nanobubble generator can be estimated from the pH, using the equation CO2=KH/2.8*10^(7.90-pH).

  • Persistent CO2 concentration

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    Open vessel

    After dissolving CO2 in water using nanobubbles, the pH rises and DCO2 decreases gradually in 3 weeks.

    This indicates that CO2 nanobubbles remain in the water for a long time, longer than O2.

    (O2 disappears in 1 week).

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    ​Closed vessel

    In closed bottles pH and DCO2 remain low and high, respectively, for a very long time.

  • Removal of CO2

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    After adding fytoplankton to the CO2-nanobubble water, pH rises rapidly and CO2 is removed within 2 days. The microalgae use the CO2 to produce carbon-rich lipids.

  • Our CO2 nanobubble generators

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    Transfer efficiency of our systems for CO2 is approx. 94%