NO Removal from Simulated Flue Gas with a NaClO2 Mist Generated Using the Ultrasonic Atomization Method

Abstract

In order to enhance the mass transfer efficiency between gas–liquid interfaces, NaClO2 mist generated by an ultrasonic humidifier was used to remove NO from simulated flue gas. The effects of some key parameters (the gas flow rate, the NaClO2 concentration in the solution, the inlet NO concentration, the NaClO2 solution pH) on NO removal efficiency were investigated preliminarily. The results showed that NaClO2 mist could oxidize NO with a much higher efficiency compared with other mists containing either NaClO or H2O2 as oxidants. With an increase in the gas flow rate from 1.5 to 3.0 L·min−1, the atomizing rate of the NaClO2 solution increased almost linearly from 0.38 to 0.85 mL·min−1. When the gas flow rate was 2.0 L·min−1, a complete removal of NO had been reached. NO removal efficiency increased obviously with an increase in the NaClO2 concentration in the solution. With an increase in the inlet NO concentration, the ratio of NO in the flue gas and NaClO2 in the mist increased almost linearly. Furthermore, the NaClO2 mist exhibited a relatively stable and high NOx removal efficiency in a wide pH range (4–11) of NaClO2 solutions. The reason for the high NO removal efficiency was mainly ascribed to both the strong oxidative ability of NaClO2 and the improved mass transfer at the gas-liquid interface.

Keywords

• nitric oxide
• ultrasonic atomization
• sodium chlorite
• mist