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X-ray Studies of Carbon Dioxide Intercalation in Na-Fluorohectorite Clay at Near-Ambient Conditions
We show experimentally that gaseous CO<sub>2</sub> intercalates
into the interlayer space of the synthetic smectite clay Na-fluorohectorite
at conditions not too far from ambient. The mean interlayer repetition
distance of the clay when CO<sub>2</sub> is intercalated is found
to be 12.5 Å for the conditions −20 °C and 15 bar.
The magnitude of the expansion of the interlayer upon intercalation
is indistinguishable from that observed in the dehydrated–monohydrated
transition for H<sub>2</sub>O, but the possibility of water intercalation
is ruled out by a careful analysis of the experimental conditions
and repeating the measurements exposing the clay to nitrogen gas.
The dynamics of the process is observed to be dependent on the pressure,
with a higher intercalation rate at increased pressure. The rate of
CO<sub>2</sub> intercalation at the studied conditions is found to
be several orders of magnitude slower than the intercalation rate
of water or humidity at ambient pressure and temperature