In-Furnace Control of Arsenic Vapor Emissions Using Fe₂O₃ Microspheres with Good Sintering Resistance

Abstract

The addition of Fe2O3 into furnaces is a promising method for arsenic pollution control. Nevertheless, Fe2O3 particles undergo serious sintering under actual furnace temperatures. To improve its sintering resistance, Fe2O3 hollow microspheres were synthesized by the template method and were tested in flue gas containing SO2 and NO in the range of 1000–1300 °C. The results demonstrated that the amount of arsenic captured could be steadily maintained above 5 mg/g throughout the operating temperature range, and Fe2O3 microspheres could maintain the originally developed pore structure and hollow morphology well even at 1200 °C. Based on product analysis and density functional theory calculations, the fixation pathway of arsenic was proposed. In no oxygen conditions, As2O3 was first bound to the Fe2O3 surface by forming an −O–As–O–Fe stable structure and then was oxidized by lattice oxygen. The introduction of O2 could regenerate the consumed lattice oxygen and therefore promote arsenic capture. Finally, the oxidized arsenic was fixed in products in the form of FeAsO4. Additionally, the impact of acid gases was also investigated. SO2 showed a notable inhibiting effect on arsenic capture, while the impact of NO was less noticeable.

Microscopic Spherical α-Fe2O3 for Highly Efficient Gaseous Arsenic Capture in Simulated Flue Gas Under a Wide Temperature Range

“…To further explain this phenomenon, FT-IR was carried out to study the changes of active functional groups on the surface of sorbent before and after the reaction. As shown in Figure , when SO 2 was introduced into the reaction, the new characteristic peak appeared at about 1160 cm –1 , which could be attributed to HSO 4 – or SO 4 2– . , SO 2 was converted to SO 3 under the catalytic oxidation of α-Fe 2 O 3 . Subsequently, under the action of water vapor, SO 3 was attached to the surface or pores of the sorbent in the form of HSO 4 – /SO 4 2– .…”

“…NO has little effect on adsorption performance, far less obvious than SO 2 . The role of O 2 is closely related to the adsorption process, and the lattice oxygen and chemisorbed oxygen are the main factors affecting the migration and adsorption capacity of gas-phase arsenic …”

“…24 The role of O 2 is closely related to the adsorption process, and the lattice oxygen and chemisorbed oxygen are the main factors affecting the migration and adsorption capacity of gas-phase arsenic. 49 Compared with CaO and Al 2 O 3 , Fe 2 O 3 is a more efficient metal oxide sorbent. 11,27,28 Fe 2 O 3 widely exists in nature as hematite, with convenient sources, low price, various kinds, high surface activity, and a large specific surface area.…”

Metal–Organic-Framework-Derived Ball-Flower-like Porous Co3O4/Fe2O3 Heterostructure with Enhanced Visible-Light-Driven Photocatalytic Activity

“…However, the minor peak at around 732.2 eV suggests that a little Fe 3+ was reduced to Fe 2+ along with the oxidation of Co 2+ to Co 3+ [19][20][21][22][23]. SEM images of the CF heterostructure are shown in Figure 2a-c.…”

“…It was revealed that Fe 3+ ions were still dominant, which corresponded to the Fe 2 O 3 phase. However, the minor peak at around 732.2 eV suggests that a little Fe 3+ was reduced to Fe 2+ along with the oxidation of Co 2+ to Co 3+ [ 19 , 20 , 21 , 22 , 23 ].…”