The Adsorption of Nitrogen Monoxide on Iron-treated Activated Carbon Fibers

Abstract

Activated carbon fibers (ACF) were treated with iron salt solutions at suitable temperatures and pH's to precipitate different kinds of iron oxide in order to increase the adsorption activity for NO. The iron-treated ACF samples were examined by the static NO adsorption at 30°C, pulse adsorption of 1 ml NO at 30°C, and flow adsorption from a 300 ppm NO-N₂mixed gas at 100°C. The adsorption isotherms for NO on each iron-treated ACF were of the Langmuir type. The Langmuir b constants were over 0.1 g/g, which were several times larger than the original ACF and commercial activated carbons. The treatment also increased the amounts of both pulse and flow adsorption. In particular, the treatment in similar conditions as that in a formation of α-FeOOH or β-Fe0OH showed the highest NO adsorption activity. The micropore structure of the iron-treated ACF was discussed from nitrogen adsorption. The considerable increase of NO adsorption has been inferred with reference to the micropore change and the amount of iron deposited on the ACF.