Mayenite based supports for atmospheric NOx sampling

- We synthetized and characterized new Calcium/mayenite substrates for the atmospheric NOx removal.
- We tested the NOx sorption capacity of the materials in laboratory environment.
- We evaluated the CO2 interference on the adsorption process.
- We tested the materials in a passive sampling device for field NOx measurements and removal.

In order to obtain a class of calcium based sorbent materials for the quantification and possibly the removal of NOx from the atmosphere, we synthesized and characterized various CaO/Mayenite (Ca12Al14O33) substrates having different weight ratio (w/w) composition. Their reactivity towards NO and NO2 was evaluated by means of several experimental techniques: FT-IR and XRD were used to characterize the species formed during the sorption process, while IC and TGA analysis provided information about the dynamics of the sorption process itself. The hydration reaction occurring on the substrate before NOx sorption has also been considered in our investigation. We finally tested the performance and the reliability of the CaO/mayenite materials in field measurements by incorporating the substrate in a passive sampler device. The simultaneous sorption of atmospheric NO2 and NO has been investigated and the role of the carbon dioxide in the NOx - CO2 exchange reactions has been assessed. According to the data reported in this paper and thanks to the fairly low cost of production, CaO/Mayenite substrates represent a good class of inorganic alkaline sorbents for NOx suitable for many applications in atmospheric sampling and remediation.

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