Capturing CO2 from ambient air - David Keith

Figure B.3: Lining the inside of the Sonotubes with PVC sheets.
The completed prototype (depicted in figures B.1 and B.2) includes a long, cylindrical “reaction chamber”
capped at the top by a permeable fabric sheet (the “laminizer”) and at the bottom by a short, largerdiameter
cylinder (the “donut”) and conical spray collection assembly (the “cone”). Liquid enters through
a spray nozzle mounted just under the laminizer and is collected to a reservoir from the bottom of the cone.
Air enters though the laminizer and leaves through four ducts attached to the top of the donut. The ducts
lead to a filter box which is in turn attached to a blower. The entire unit is relatively well-sealed against
air and liquid escaping and the blower keeps it all at negative pressure, further insuring against fugitive
emissions.
For the reaction chamber we considered various wood-frame assemblies with plastic film or plastic
sheet skin and prefabricated plastic tanks, but ultimately chose to construct the main body out of Sonotubes,
heavy-duty cardboard tubes used as forms for pouring concrete columns. The Sonotubes provided
stiff, precisely cylindrical walls that would stand up to negative pressure and support the top-mounted
spray apparatus structurally.
The largest Sonotubes available had a 4 ft inner diameter and 4 ft length. Three lengths were fastened
together with a fiberglass and epoxy wrap to produce a 12 ft total height of the reaction chamber. The
Sonotubes were lined with 1/8 in-thick PVC sheets which were affixed to the waxed cardboard interior
surface with epoxy (see Figure B.3). Silicon sealant was used to fill the seams. Once the Sonotubes were
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