Decrease of Concentration of Impregnated Nitrite on Filter
1982 Volume 17 Issue 2 Pages 102-108
Details
1982 Volume 17 Issue 2 Pages 102-108
NO2--impregnated filter (12-1500μgNO2-/a filter) was prepared, statically, by adding NaNO2 methanol solution to quartz filter.[NO2-]-decrease rate on the filter was investigated by air-flow through the filter under various conditions, as well as on standing in the desiccator with known relative humidity (RH) controlled by isopiestic method.
It was proved that O2-H2O and O3 (-H2O) in the air were main substances to decrease the [NO2-]. NO2- on the filter reacts with O2-H2O by the following equation: 3HNO2=HNO3+2NO+H2O and HNO2+1/202→ HNO3, as in NO2- aqueous solution and with O3 (-H2O) by the follow: NO2-+O3=NO3-+O2.
In the O2-H2O system, [NO2-]-decrease rate was increased with an increase of RH in the air, but the rate near RH= 100% became slow. The behavior near RH= 100% was concluded that the surface/volume ratio of particulate NO2- was reduced at the RH, making O2 attack to the NO2- difficult.
