J. Hofele et al., ABSORPTION OF NO IN AQUEOUS-SOLUTIONS OF FE(II)NTA - DETERMINATION OFTHE EQUILIBRIUM-CONSTANT, Chemical engineering and processing, 35(4), 1996, pp. 295-300
Valid alternatives to the selective catalytic reduction (SCR) process
for the removal of nitrogen oxides from waste gases (denoxing) may be
found in wet scrubbing processes where the low solubility of NO in aqu
eous media is enhanced by the application of chelate complexes. The mo
st widely used complex for this purpose is Fe(II)EDTA (iron(II) ethyle
nediaminetetra-acetic acid). Iron(II) nitrilotriacetic acid (Fe(II)NTA
) might be another candidate, with similar chemical properties as Fe(I
I)EDTA but available industrially at a considerably lower price. For t
he development of technical processes, a knowledge of the equilibrium
data over a range of temperature is of prime importance. Therefore exp
erimental investigations were carried out concerning the chemical equi
librium of the reaction: NO + Fe(II)NTA reversible arrow Fe(II)NTA . N
O The equilibrium constant was determined in the temperature range 22-
80 degrees C. All experimental data fit the equilibrium constant equat
ion well: K-p = 3.05 x 10(-8) exp(7332/T) (bar(-1)) The equilibrium co
nstant for Fe(II)NTA is approximately 25% lower than the constant for
Fe(II)EDTA. However, considering the price difference between the two
complexants, Fe(II)NTA is an interesting alternative to Fe(II)EDTA.