Ammonia traces detection based on photoacoustic spectroscopy for evaluating ammonia volatization from natural zeolites at typical crop field temperature

A Brazilian sedimentary zeolite-containing microporous material was characterized by determining its physical and chemical properties (surface area, pore volume, dinitrogen and ammonia desorption rates, oxide composition, and acid site characterization), and compared with two commercial natural zeolites. The characterization of these materials was performed using N2 adsorption, X-ray fluorescence spectroscopy and temperature programmed desorption (TPD) techniques. Using photoacoustic spectroscopy, the performance of these microporous materials in the adsorption and delayed desorption of nitrogen-containing fertilizers was studied by monitoring the ammonia emission rate after their treatment with ammonium sulfate. Ammonia desorption curves were recorded under 30 °C and 60 °C, aiming to reproduce typical Brazilian cropfield temperature conditions.