Theoretical Study of As2O3 Adsorption Mechanisms on CaO surface

Abstract

Emission of hazardous trace elements, especially arsenic from fossil fuel combustion, have become a major concern. Under an oxidizing atmosphere, most of the arsenic converts to gaseous As2O3. CaO has been proven effective in capturing As2O3. In this study, the mechanisms of As2O3 adsorption on CaO surface under O2 atmosphere were investigated by density functional theory (DFT) calculation. Stable physisorption and chemisorption structures and related reaction paths are determined; arsenite (AsO33−) is proven to be the form of adsorption products. Under the O2 atmosphere, the adsorption product is arsenate (AsO43−), while tricalcium orthoarsenate (Ca3As2O8) and dicalcium pyroarsenate (Ca2As2O7) are formed according to different adsorption structures.

The synthesis of calcium arsenate@iron arsenate coating materials and their application for arsenic-containing wastewater treatment

“…01-0933). 19 Sample 1 and sample 2 were the two most common calcium arsenate phases in the arsenic-containing wastewater treatment.…”

Computational Studies on the Interaction of Formaldehyde Vapor with δ‐Phosphorene Nanosheet: A DFT Insight

“…The adsorption energy upon interaction of formaldehyde with δ‐P infers the physisorption nature. Since the adsorption energy value is −1 eV, the weak adsorption energy leads to van der Waals type of adsorption . The adsorption energy ranges from −0.116 eV to −0.971 eV.…”

Adsorption of NOxwith NH3on γ-Al2O3and Its Effects on the Adsorption of As2O3Based on DFT

“…Zhang et al pointed out that Fe 2 O 3 /γ-Al 2 O 3 could adsorb As 2 O 3 with the effect of catalytic oxidation . Yaming et al illustrated that As 2 O 3 could be transformed into AsO 4 3– and AsO 3 3– with or without O 2 on the CaO (0 0 1) surface, while tricalcium orthoarsenate (Ca 3 As 2 O 8 ) and dicalcium pyroarsenate (Ca 2 As 2 O 7 ) could be formed according to different adsorption structures . Lee et al pointed out that TiO 2 could demonstrate a decent arsenic retention property which could be further enhanced after being sulfated because of the increment of Lewis and Bronsted acid sites .…”

“…5 Yaming et al illustrated that As 2 O 3 could be transformed into AsO 4 3− and AsO 3 3− with or without O 2 on the CaO (0 0 1) surface, while tricalcium orthoarsenate (Ca 3 As 2 O 8 ) and dicalcium pyroarsenate (Ca 2 As 2 O 7 ) could be formed according to different adsorption structures. 6 Lee et al pointed out that TiO 2 could demonstrate a decent arsenic retention property which could be further enhanced after being sulfated because of the increment of Lewis and Bronsted acid sites. 7 Wang et al conducted a set of experiments and discovered that different flue gas constituents could affect arsenic adsorption by Fe 2 O 3 /γ-Al 2 O 3 , in which the overly high CO 2 concentration inhibited arsenic adsorption, O 2 /H 2 O(g) accelerated the arsenic adsorption process, and the arsenic adsorption capacity increased first and then decreased when the concentration of SO 2 increased.…”