Experimental study on FeIICit enhanced absorption of NO in (NH4)2SO3 solution

•FeIICit can increase the solubility of NO in (NH4)2SO3 solution to enhance NO absorption.•FeIICit has good features, such as competitive price and environmental friendliness.•NO absorption mechanism and removal efficiency were analyzed.•The method provides technical reference for reinforced wet denitrification. FeIICit and (NH4)2SO3 mixed solution was selected as denitrification absorbent, and enhanced absorption of NO was studied in a bubbling reaction column. The results show that, the highest NO removal efficiency achieved under the molar ratio of FeII to Cit was 1:2, NO removal efficiency decreased slightly with the increase of pH in the range of experimental pH, the NO removal efficiency reduced with the increase of temperature. NO removal efficiency increased slightly with the increasing concentrations of import NO, but decreased with the increasing gas flow rate. Validated experiment was carried out under the optimum conditions in the double columns, the NO removal efficiency reached up to 71.66% within 1min and 48.14% within 6min.