Workplace Nitrous Oxide Sampling: Alternative Adsorbents

This study was dedicated to the improvement of nitrous oxide sampling for occupational exposure assessment. The current method is based on diffusive sampling of N2O on 5Å molecular sieve. Its application is constrained due to back-diffusion phenomenon observed on this adsorbent. Cationic ZSM5 zeolites were prepared, characterized and tested for nitrous oxide adsorption. Their performances where found to be function of the number and the nature of exchange cations. The influence of water vapour in the stream was also investigated. In a second step, the uptake rate of each zeolitic adsorbent was determined in order to evaluate back-diffusion phenomenon. Higher adsorption capacities, in presence and in absence of water vapour, were obtained on Ba-exchanged ZSM5 zeolites of Si/Al ratio of 11. Additionnally, no back diffusion was observed on this adsorbent. BaZSM5(11) appears to be a suitable solid to replace 5Å for the diffusive sampling of N2O.