Novel Simultaneous Removal Technology of NO and SO₂ Using a Semi-Dry Microwave Activation Persulfate System

Abstract

As it has a simple system and a small floor area, flue gas simultaneous desulfurization and denitrification technology has a good development prospect, and related research has become a hot topic in the field of flue gas purification. In this work, a novel simultaneous removal technology of NO and SO 2 from flue gas using a semi-dry microwave activation persulfate system was developed for the first time. A series of experiments and characterization analyses had been implemented to research the feasibility of this new flue gas purification technology. The oxidation products, free radicals, and mechanism of NO and SO 2 simultaneous removal were revealed. The effect of the main technological parameters on NO and SO 2 simultaneous removal was also studied. Relevant results demonstrated that an increase in the microwave radiation power, persulfate concentration, and O 2 concentration enhanced NO and SO 2 simultaneous removal. The increase of NO and SO 2 concentrations weakened NO and SO 2 simultaneous removal. The reagent dosage, pH value of the solution, and reaction temperature showed a dual influence on NO and SO 2 simultaneous removal. Free-radical capture experiments revealed that both SO 4 −• and • OH that were produced by microwave activation of persulfate were the major active species and played very key roles in NO and SO 2 simultaneous removal. The main products (sulfate and nitrate) and byproducts (NO 2 ) in the tail gas were found. The process application and product post-treatment routes were also proposed. The result may provide the necessary inspiration and guidance for the development and application of microwave-activated advanced oxidation technology in the flue gas treatment area.

A Critical Review on Removal of Gaseous Pollutants Using Sulfate Radical-based Advanced Oxidation Technologies

“…Relevant results ,,,, showed that compared with ultrasonic, photochemical and electrochemical activation, microwave activation had longer radiation distance because it can even penetrate solids, possessing a good prospect of application. In the field of water treatment, some researchers employed microwave to activate peroxides (i.e., H 2 O 2 , PS, and PMS) to generate free radicals to degrade organic contaminants from wastewater. ,,,,,,,, However, microwave-activated SO 4 • – -based AOTs are not suitable for wastewater treatment because most of the microwave radiation energy will be consumed in heating and evaporation of water, instead of activating oxidants.…”

“…In the field of gaseous pollutants removal, several researchers ,, used catalysts under microwave activation to remove gaseous pollutants. However, this kind of microwave activation system led to an operation temperature of over 1000 °C because of uncontrollable heating characteristics of microwave in a dry treatment device, which poses a great challenge to the life of catalysts and the safe of device operation. ,,,,,, …”

“…In order to reduce energy consumption and operating temperature, realizing the economical and safe operation of the device, Liu et al developed a kind of semidry microwave-activated SO 4 • – -based AOT via designing a microwave reactor with multifunctions of vaporization-activation-oxidation. Compared with the microwave activation system in wastewater treatment, the developed semidry microwave activation system only needs activate trace reagent solution.…”

Application Prospect of K Used for Catalytic Removal of NOx, COx, and VOCs from Industrial Flue Gas: A Review

“…The global warming potential of N 2 O is 310 times higher than that of CO 2 [3], and soot is theoretically the second largest global warming factor after CO 2 due to its radiative forcing effect [1,4]. NO x also causes ozone layer destruction and acid rain [5]. In addition, NO x , CO, and VOCs cause human poisoning.…”

Scale-up experiments of SO2 removal and the promoting behavior of NO in moving beds at medium temperatures

“…13,14 Dry simultaneous control technologies are promisingly investigated without large water assumptions and low secondary pollution. [15][16][17][18][19][20][21][22][23][24][25][26][27] Among the dry integrated multi-pollutant removal technologies, the carbon-based catalyst-integrated removal technology was widely studied, 28,29 particularly in the sintering ue gas industry. 30 Activated coke/activated carbon is used as a dry adsorbent.…”