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.
Highlights
A great deal of air pollutants are emitted from the combustion of fossil fuels in stationary sources and mobile sources every year, which results in serious damage to the ecological environment [1,2].During the past decades, numerous efforts have been made to effectively remove sulfur oxides (SOx ), nitrogen oxides (NOx ), particle matters (PMs), and other air pollutants, from the waste gas [3].Comparatively speaking, it is easy to decrease the emission of SOx and PMs with a high efficiency by adopting a wet scrubbing method [4,5]
A NaClO2 mist generated by an ultrasonic humidifier was used to remove NO from simulated flue gas, and the effects of some key operating parameters on the NO removal efficiency were investigated experimentally; the possible reaction pathways are discussed
NaClO2, NaClO, and H2 O2 are common oxidants that are used to remove NO from flue gas through wet scrubbing. They are chosen to combine with the ultrasonic atomization process in through wet scrubbing
Summary
Numerous efforts have been made to effectively remove sulfur oxides (SOx ), nitrogen oxides (NOx ), particle matters (PMs), and other air pollutants, from the waste gas [3]. Speaking, it is easy to decrease the emission of SOx and PMs with a high efficiency by adopting a wet scrubbing method [4,5]. SCR can remove NOx with an efficiency of 80–95% and it has been successfully applied in power plants, heavy-duty vehicles, and ocean-going ships [7,8]. There are still some challenges for SCR to deal with. It requires a large installation space and has a high investment cost [9].
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