Nitrogen oxides absorption into aqueous nitric acid solutions containing hydrogen peroxide tested using a cables-bundle contactor

Abstract

This work aims to study the removal of dilute nitrogen oxides from gaseous effluents by absorption into aqueous nitric acid solutions containing or not hydrogen peroxide. NOx absorption tests (pNOx = 50 Pa with a varying composition) were performed in a cables-bundle contactor at ambient conditions. Tests runs were carried out with the recycling of the absorbent solution (0–8 mol/l for HNO 3 and 0–2 mol/l for H 2 O 2 ) allowing to observe the temporal evolution of the absorption efficiency. The effects of the different operating conditions on the NO, NO 2 and NOx absorption performances (A) were investigated. Results revealed in all the cases that A NOx increases when increasing the proportion of more oxidized species in NOx. Without H 2 O 2 A NOx decreases when the HNO 3 concentration of the solution is increased and also with the recycling of the scrubbing liquid, leading to NOx desorption phenomena. When hydrogen peroxide is added to the nitric acid solution the NOx absorption performances are much higher and increase with the initial H 2 O 2 concentration and the HNO 3 concentration. • A NOx increases when increasing the proportion of more oxidized species in NOx. • Without H 2 O 2 , A NOx decreases when the HNO 3 concentration of the solution is increased and also with the recycling of the scrubbing liquid, leading to NOx desorption phenomena. • When H 2 O 2 is added to HNO 3 solution, A NOx is much higher and increases with the initial concentration of H 2 O 2 and HNO 3 .