Simultaneous absorption of SO2 and NOx from simulated flue-gas exploiting the enhancing oxidative ability of aqueous euchlorine as scrubbing solution.

[Display omitted] • Euchlorine-based WOS completely removes NO x on top of SO x. • SO 2 plays a synergistic role in NO x absorption. • Acidity promotes a gas–liquid dual oxidation making the de-NO x process more efficient. • WOS under acidic conditions saves 83% chemical and 70% water. • WOS can be a viable alternative to the conventional FGD-SCR plants. This paper reports the performances of a pilot-scale Wet Oxidative Scrubber (WOS) in the treatment of a simulated flue-gas containing 500 ppm v SO 2 and 1030 ppm v NO x and operated at 60 °C and 1 atm. The scrubber is fed with an oxidizing solution containing NaClO 2 at either 0.75 % or 1 % w/w initially at pH > 9 and then acidified to pH down to 3 with HCl, to obtain the additional oxidative contribution given by euchlorine species during the simultaneous absorption. Further experiments of single-component NO x absorption are performed to better understand the role exerted by SO 2 in the simultaneous absorption. These experimental tests are carried out to investigate the effect of the acidity of the chlorite-based scrubbing solution on the simultaneous absorption performance of SO 2 and NO x , highlighting the intensification with respect to the bare de-NO x system. Experiments also allow determining the optimal dosages and solution pH for a complete and optimized removal of NO x and SO x also being less energy-intensive. For a scrubbing solution under acid-induced conditions (pH = 3), the retrieved results show that the NaClO 2 molar dosage needed for a complete simultaneous removal results 3.6 times greater than the total NO x concentration in the flue-gas. This allows an interesting reduction of 83 % in oxidant consumption and a water-saving of 70 % with respect to the same process applied to the simultaneous NO x absorption but without altering the solution pH. Overall, the results confirm the enhancing role exerted by euchlorine deriving from chlorite acidification and sulfur dioxide presence in the flue-gas. [ABSTRACT FROM AUTHOR]