Adsorption of Nitrogen Dioxide on Activated Carbont

URANO Kohei, TANIKAWA Noboru, MASUDA Toshio, KOBAYASHI Yoshitaka

doi:10.1246/nikkashi.1977.124

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Other Title

二酸化窒素の活性炭に対する吸着特性
排ガスの吸着処理　Ｉ　　二酸化窒素の活性炭に対する吸着特性

Description

Isotherms and rates of adsorption of NO₂ as well as adsorbed species on 3 kinds of activated carbon in N₂, N₂ + H₂0 or N₂ + H₂0 + 0₂ atomosphere were investigated as a fundamental study for a removal of nitrogen oxides from exhaust gas. The temperature range was 50-125°C, and the concentration ranges of NO₂, H₂0 and 0₂ were 50-5000 ppm, 1.4-30% (relative humidity: 3.6-79%) and 2.5-40%, respectively.<BR>NO₂ in N₂ is adsorbed as such, but in N₂ + H₂O as nitric acid. The content of adsorbed HNO₃ (y%) is expressed by the following equation: y=100-8.6 x^0.56, when the relative humidity (x%) is larger than 6 (Table 4, Fig.8). The adsorption isotherms are expressed by Freundlich equation (Fig.3, 4, 9, 10, Table 2, 5). The activated carbon with, large specific surface area has excellent adsorption capacity (Table 1, Fig.2, 9). The apparent adsorbed amount in N2 + H20 increases with increasing relative humidity (Fig.10). The adsorbed amount, converted to NO₂, is nearly equal to that in N2 when the relative humidity is 6.50%, but it decreases rapidly above 50% (Table 6). The adsorption rate is controlled by the intraparticle diffusion (Fig.5, 12). The intraparticle diffusivity is proportional to eight tenths power of the concentration of NO₂ (Table 3, 7, Fig.6), and scarcely different among 3 kinds of activated carbon. The effect of coexistence of 02 on the adsorption of NO2 could not be observed (Fig.13).

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