Absorption of dilute sulfur dioxide in ethanediamine with ethylene glycol or polyethylene glycol 400 plus water system

Capturing sulfur dioxide (SO2) with organic solvent is a promising desulfurization method because of not only its superior performance of absorption and desorption for SO2 but also the recyclable feature of solvent. Therefore, the dilute sulfur dioxide (SO2) absorption in ethanediamine with ethylene glycol (EG) or various aqueous polyethylene glycol 400 (PEG400) solutions was studied in this work. The experimental results illustrate that the systems of pure ethanediamine and ethanediamine with PEG400 or PEG400 plus water can generate white precipitation after absorbing SO2 and these precipitations have same chemical constitution with the molecular structural formula being H2O⋯NH2CH2CH2NHH⋯OSO, revealing that a molecular ethanediamine reacts just with a molecular SO2 and the interaction of them is attributed to the hydrogen bonding. Additionally, the decomposition temperature of the precipitation may be 168 °C and PEG400 solution can be recycled originating from the white precipitation being separated easily through heating for a while in the hot water, which is deemed as a potential method for SO2 removal.