Simultaneous Desulfurization and Denitrification from Flue Gas by Ferrate(VI)

Abstract

An innovative semidry process has been developed to simultaneously remove NO and SO₂ from flue gas. According to the conditions of the flue gas circulating fluidized bed (CFB) system, ferrate(VI) absorbent was prepared and added to humidified water, and the effects of the various influencing factors, such as ferrate(VI) concentration, humidified water pH, inlet flue gas temperature, residence time, molar ratio of Ca/(S+N), and concentrations of SO₂ and NO on removal efficiencies of SO₂ and NO were studied experimentally. Removal efficiencies of 96.1% for SO₂ and 67.2% for NO were obtained, respectively, under the optimal experimental conditions, in which the concentration of ferrate(VI) was 0.03 M, the humidified water pH was 9.32, the inlet flue gas temperature was 130 °C, the residence time was 2.2 s, and the molar ratio of Ca/(S+N) was 1.2. In addition, the reaction mechanism of simultaneous desulfurization and denitrification using ferrate(VI) was proposed.

Properties of carbon dioxide absorption and reduction by sodium borohydride under atmospheric pressure

“…After that, the absorption efficiency increases rapidly with pH from 4.0 to 9.0 and the efficiency of about 50% is achieved at 9.0, which can be attributed to the inhibitory effect of high pH on NaBH 4 self-hydrolysis. However, the absorption efficiency keeps basically unchanged within the range of 9.0-13.0, implying that the self-hydrolysis of NaBH 4 is inhibited at high pH, which is favorable to CO 2 absorption, meanwhile its reactivity is also decreased [25,29,30]. Based on the works of Iwakura et al [31] and Fenimore and Jones [32], the excessive amounts of hydroxide (OH À ) at high pH were disadvantageous to CO 2 reduction.…”

New insights into synergistic effects and active species toward Hg0 emission control by Fe(VI) absorbent

“…These factors directly affect the removal efficiencies of Hg 0 . Generally speaking, Fe(VI) can exist in the forms of H 3 FeO 4 + , H 2 FeO 4 , HFeO 4 À , and FeO 4 2À within aqueous environment [23,32].…”

“…In addition, the reduced ions could be recycled to use as raw materials for Fe(VI) production. The gypsum byproducts can be used in construction [23].…”

Simultaneous photocatalytic elimination of gaseous NO and SO 2 in a BiOI/Al 2 O 3 -padded trickling scrubber under visible light

“…Once released into the atmosphere, they could cause detrimental effects to human health and ecosystems, including acid rain, photochemical smog, ozone destruction and atmospheric visibility degradation [1][2][3]. Typically, the wet flue gas desulfurization (WFGD-Ca) combined with selective catalytic reduction (NH 3 -SCR) was commercialized well due to its high removal efficiency of SO 2 and NO x .…”

“…To improve oxidation rate of NO to NO 2 at ambient condition, the stronger oxidants such as Fe(VI) [2], sodium chlorite [6], sodium humate [7], UV/H 2 O 2 [8], ozone [9] etc., have been applied to remove NO and SO 2 . Although a considerable removal for NO and SO 2 could be achieved, oxidation processes consume excessive chemicals to completely react with NO and SO 2 and there are also concerns of unwanted oxidation products such as toxic chlorinated or ozonized by-products from chlorination or ozonation processes [2].…”