Review on Removal of SO2, NOx, Mercury, and Arsenic from Flue Gas Using Green Oxidation Absorption Technology

Emission of SO2, NOx, mercury (Hg), and arsenic (As) from flue gas has become a great public concern due to their hazards for human health and ecosystems. Simultaneous removal of multipollutants (two or more of SO2, NOx, Hg, and As) has good development prospects due to its simple system and low cost. Although many multipollutant simultaneous removal technologies have been developed, green oxidation absorption is one of the most promising technologies because it can not only make full use of the existing WFGD devices, but also its treatment process is clean. This review analyzes the latest research advances in the removal of SO2, NOx, Hg, and As from flue gas using green oxidation absorption technologies. The performance, mechanism, and kinetics of SO2, NOx, Hg, and As removal are reviewed. The merits and drawbacks of these green oxidation absorption technologies and the potential research directions are commented on. This review indicates that each technology has its own advantages and disadvantages in terms of removal efficiency, cost, reliability, and product post-treatment. Photochemical and electrochemical removal technologies have a high free radical yield and pollutant removal efficiency, but they have complex systems, high energy consumption, or unreliable systems. Metal oxide-activated peroxide oxidation technology has a good prospect due to its simple process, low device requirements, and recyclability of catalysts. However, it also has shortcomings such as a low free radical yield and easy deactivation of catalysts. Other technologies also have some disadvantages, such as high cost, low free radical yield, difficult separation of products, complex equipment, and/or low reliability. Synergic use of multitechnologies may be a promising strategy because it can make up for the shortcomings of each technology.