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 NO 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.