2 research outputs found
Water radiolysis in exchanged-montmorillonites: the H2 production mechanisms.
International audienceThe radiolysis of water confined in montmorillonites is studied as a function of the composition of the montmorillonite, the nature of the exchangeable cation, and the relative humidity by following the H2 production under electron irradiation. It is shown that the main factor influencing this H2 production is the water amount in the interlayer space. The effect of the exchangeable cation is linked to its hydration enthalpy. When the water amount is high enough to get a basal distance higher than 1.3 nm, then a total energy transfer from the montmorillonite sheets to the interlayer space occurs, and the H2 production measured is very similar to the one obtained in bulk water. For a basal distance smaller than 1.3 nm, the H2 production increases with the relative humidity and thus with the water amount. Lastly, electron paramagnetic resonance measurements evidence the formation of a new defect induced by ionizing radiation. It consists of a hydrogen radical (H2 precursor) trapped in the structure. This implies that structural hydroxyl bonds can be broken under irradiation, potentially accounting for the observed H2 production
Water Radiolysis in Exchanged-Montmorillonites: The H<sub>2</sub> Production Mechanisms
The
radiolysis of water confined in montmorillonites is studied
as a function of the composition of the montmorillonite, the nature
of the exchangeable cation, and the relative humidity by following
the H<sub>2</sub> production under electron irradiation. It is shown
that the main factor influencing this H<sub>2</sub> production is
the water amount in the interlayer space. The effect of the exchangeable
cation is linked to its hydration enthalpy. When the water amount
is high enough to get a basal distance higher than 1.3 nm, then a
total energy transfer from the montmorillonite sheets to the interlayer
space occurs, and the H<sub>2</sub> production measured is very similar
to the one obtained in bulk water. For a basal distance smaller than
1.3 nm, the H<sub>2</sub> production increases with the relative humidity
and thus with the water amount. Lastly, electron paramagnetic resonance
measurements evidence the formation of a new defect induced by ionizing
radiation. It consists of a hydrogen radical (H<sub>2</sub> precursor)
trapped in the structure. This implies that structural hydroxyl bonds
can be broken under irradiation, potentially accounting for the observed
H<sub>2</sub> production