Workplace Nitrous Oxide Sampling: Alternative Adsorbents

MW-Assisted Regeneration of 13X Zeolites after N2O Adsorption from Concentrated Streams: A Process Intensification

N2O has a global warming potential about 300 times higher than CO2, and even if its contribution to the greenhouse effect is underrated, its abatement in industrial production’s tail gas has become imperative. In this work, we investigate the feasibility of the microwave (MW)-assisted regeneration of a 13X zeolite bed for N2O capture from tail gases. Several consecutive adsorption–desorption cycles were performed to verify the microwave heating effect on the zeolite’s adsorption properties. The results of the experimental tests, performed at N2O concentrations of 10, 20 and 40% vol, highlighted that (i) the steps are perfectly repeatable in terms of both adsorbed and desorbed amount of N2O, meaning that the MWs did not damage the zeolite’s structure, (ii) the presence of both H2O and O2 in the feed stream irreversibly reduces the adsorbent capacity due to nitrites and nitrates formation, and (iii) the presence of H2O alone with N2O still reduces the adsorbent capacity of the zeolites, which can be recovered through MW-assisted regeneration at 350 °C. Moreover, the MW-assisted TSA assured an energy and purge gas saving up to 63% and 82.5%, respectively, compared to a traditional regeneration process, resulting in effective process intensification.

Parameters determining the performance of passive flux samplers proposed as a tool to estimate N2O emissions: evaluation at farm level and perspectives

The passive flux sampling is an economic and easy way to estimate gas emissions from agriculture sources. In the last decade, specific passive flux samplers (PFSs) have been developed to estimate nitrous oxide (N₂O) emissions from agriculture sources. Packed with silica gel and zeolite 5A, the PFSs were placed facing the emission source direction close to the ventilation shafts. For validation, air samples were taken at different sampling time during 3 days on two commercial sites. The adsorbed mass of N₂O in PFSs was recovered by thermal desorption in the laboratory. Results indicated that the mass of N₂O adsorbed in PFSs was from 1.5 to 5.5 μg. A specific adsorption pattern was observed for each sampling. In farm 1, the mass of N₂O adsorbed in the PFSs presented a linear behavior as a function of sampling time, and the most determined coefficient values were higher than 0.80. In farm 2, in addition to the sampling time, the N₂O concentration and the air flow rate presented an effect on the mass adsorbed in the PFSs. On the other hand, comparison of PFSs versus other techniques indicated that PFSs offer different advantages. However, the selectivity and capacity of the adsorbent bed used need to be improved to enhance the use of PFSs proposed as a tool to estimate N₂O emissions. Graphical Abstract PFSs enabled N₂O sampling that followed a linear behavior as a function of sampling time. Sampling time, [N₂O], and air flow rate determined the mass of N₂O collected in PFSs.

Tunable Porous Coordination Polymers for the Capture, Recovery and Storage of Inhalation Anesthetics

The uptake of inhalation anesthetics by three topologically identical frameworks is described. The 3D network materials, which possess square channels of different dimensions, are formed from the relatively simple combination of Zn^II centres and dianionic ligands that contain a phenolate and a carboxylate group at opposite ends. All three framework materials are able to adsorb N₂ O, Xe and isoflurane. Whereas the framework with the widest channels is able to adsorb large quantities of the various guests from the gas phase, the frameworks with the narrower channels have superior binding enthalpies and exhibit higher levels of retention. The use of ligands in which substituents are bound to the aromatic rings of the bridging ligands offers great scope for tuning the adsorption properties of the framework materials.