Abstract
Absorption rates of NO in aqueous solutions of Fe(II)-EDTA chelate as well as in mixed solutions of Fe(II)-EDTA and Na2SO3 were measured using a stirred vessel with a free flat gasliquid interface and a bubble column.
The rate constants of the complexing reaction of NO with Fe(II)-EDTA were determined on the basis of the theory of gas absorption accompanied by a reversible reaction. The chemical equilibrium constants were also determined at various pH values. It was found that the rate constant was of the order of 108 l/g-mol-sec and that the equilibrium constant was about 106 l/g-mol at 25°C. These values are much higher than the corresponding values of the reaction between NO and Fe(II) in the absence of EDTA.
The mechanism of the absorption of NO in mixed solutions of Fe(II)-EDTA and Na2SO3 was deduced from the observation that the absorption efficiency decreased in the early stage of absorption and then increased to some steady value. The absorption rates were satisfactorily explained on the assumption that NO coordinates to Fe(II) (EDTA) (SO2-3) irreversibly.
It was also found that the absorption rate of NO in the aqueous solution of Fe(II)-EDTA was much higher than those of other liquid absorbents so far investigated.
