Investigation of the equilibrium constant of NO absorption into diethylenetriaminecobalt(II) solution

Diethylenetriaminecobalt(II), [Co(DETA)₂]²⁺, formed by diethylenetriamine (DETA) coordinating with Co(II) ion, can be used to remove NO from flue gas. Diethylenetriaminecobalt(II) is capable of binding NO to form metal nitroso complexes. The determination of the equilibrium constant of the reaction between [Co(DETA)₂]²⁺ and NO is important to the development of the technology for the elimination of NO from exhausted gas streams with diethylenetriaminecobalt solution. In this paper, the equilibrium constants of this reaction have been determined by a series of experiments in a bubble reactor at the range of 30–70°C under atmospheric pressure in the [Co(DETA)₂]²⁺ solution of pH 7.5. All experimental data are in good agreement with the following equation: $K\left(\mathrm{T}\right)=1.8619\times {10}^{-6}\exp \left(\frac{4677.52}{T}\right)\left(\mathrm{L}\cdot {\mathrm{mol}}^{-1}\right)$, where the changes in enthalpy and entropy are ΔH⁰ = −38.89 kJ ⋅ mol⁻¹ and ΔS⁰ = −109.7 J ⋅ K⁻¹ ⋅ mol⁻¹, respectively.