Performance, optimization, and mechanism of nitric oxide removal by thiourea dioxide/FeIIEDTA reaction systems

Abstract

In this work, a new innovative absorption system containing both thiourea dioxide (TD) and FeIIEDTA was used to NO removal. The independently influences of O2 volume concentration, TD concentration, original pH value and absorbent temperature on NO removal in bubbling device were examined preliminarily. The results revealed that the NO removal efficiency firstly increased and then decreased with the increasing of the three independent variables (O2 volume concentration, TD concentration and temperature). However, the NO removal efficiency monotonously increased to some extent with pH value increasing from 6.5 to 10.5. In addition, the respective effects of the four variables and the interactive function of them on NO removal were checked with the response surface methodology (RSM) by central composite design (CCD). The calculative model showed that pH value possessed a main positive independent impact on NO removal. Furthermore, the interactive effects between any two factors were expounded by the 3D surface and counter plots. Finally, the optimum absorption conditions for the maximum NO removal at 94.3% experimentally and 95.8% statistically were obtained in O2 volume content of 6.0%, TD concentration of 0.02 mol·L−1, original pH value of 10.5 and absorption temperature of 42 °C.