Fig. 7: “Zero-emission”, recyclable NO2 adsorption on LTA zeolites under humid conditions and demonstration as “zero-NOx shields” for occupational personal protection.
From: Zero-emission NO2 capture using divalent metal cation-exchanged zeolites for air purification
a NO2 breakthrough and NO release curves for Na+-, Ca2+-, Mn2+-, and Ni2+-exchanged LTA-3 zeolites (activated at 450 oC) in humid NO2/Air (500 ppm NO2 balanced with air, containing ~2 vol% of H2O, at ~70% relative humidity, 25 °C, and 101.325 kPa). b NO2 breakthrough and NO release curves for Ca-LTA-3 (activated at 450 oC) in humid 4 ppm NO2/Air (4 ppm NO2 balanced with air, containing ~2 vol% of H2O, at ~70% relative humidity, 25 °C, and 101.325 kPa). c NO2 breakthrough and NO release curves and d corresponding NO2 uptake and percentages of released NO relative to NO2 input for Ca-LTA-3 (activated/regenerated at 450 oC) during cyclic NO2 adsorption in humid NO2/Air. e NO2 breakthrough and NO release curves for Ca-LTA-3 zeolites (activated/regenerated at 450 oC) during cyclic NO2 adsorption in humid 4 ppm NO2/Air. f Schematic illustration of our designed filter for wearable air‑purifying respirators intended for occupational personal protection. g Photograph of the fabricated prototype of our designed filter. h Photograph of the filter integrated into a commercially available respirator (3 M 6200 Half Mask; this product is solely utilized for demonstrating the integration and does not imply endorsement, affiliation, or evaluation by the manufacturer). i NO2 breakthrough and NO release curves, along with inhalation resistance of the filter during the standardized NO2 service-life test, performed using humid 500 ppm NO2 polluted air (containing ~2 vol% of H2O, at ~70% relative humidity, 25 °C, and 101.325 kPa) at a flow rate of 32 L min-1.
