Regeneration of manganese oxide as adsorption sites for hydrogen sulfide on granulated coal ash

Abstract

It is important to remove hydrogen sulfide to maintain healthy ecosystems as well as viable aquaculture activities in enclosed water bodies. Granulated coal ash with high adsorption capacity for hydrogen sulfide is a by-product generated from coal combustion processes in coal-fired power plants. The purposes of this study were to (1) verify the regeneration of the adsorption sites for hydrogen sulfide on the granulated coal ash by redox reaction which changes between oxic and anoxic conditions and (2) prove the regeneration mechanisms of the adsorption site which leads to high adsorption capacity for hydrogen sulfide. XAFS analyses of the granulated coal ash revealed that the adsorption site for hydrogen sulfide on the granulated coal ash was regenerated at least 10 times through oxidation of manganese oxide under oxic conditions. A positive correlation (r=0.995) between the peak top energy of manganese XAFS in the GCA collected from field trial sites and the Eh of the sediments applied with the GCA was observed. These results proved that hydrogen sulfide was adsorbed and oxidized by the granulated coal ash during the stratified season. During the vertical mixing seasons, oxygen regenerates the adsorption site for hydrogen sulfide. It is concluded that this 3 regeneration of adsorption site gives the granulated coal ash high adsorption capacity for hydrogen sulfide.

Speciation of Manganese in a Synthetic Recycling Slag Relevant for Lithium Recycling from Lithium-Ion Batteries

“…XANES is a convenient method to analyze the species of 3d-elements in crystalline, as well as amorphous materials. Asaoka et al determined the oxidation state of Mn in granulated coal ash via XANES [10], while Kim et al used XANES for Mn speciation in steel-making slags [11]. In general, the oxidation state, the coordination sphere, and in some cases the actual compound can be determined.…”

Manganese oxide coated TiO2 nanotube-based electrode for efficient and selective electrocatalytic sulfide oxidation to colloidal sulfur

“…Even though demonstrating fast sulfide removal rates at first, the treatment performance gradually decreases as Mn becomes depleted due to its interaction with sulfide [37]. In our previous study, we demonstrated that application of low anodic potentials enabled continuous regeneration of the MnxOy catalyst coating, thus preventing its gradual depletion [38].…”

Removal of hydrogen sulfide gas using coal fly ash – blast furnace cement composite

“…A costeffective adsorbent for removing H 2 S gas was developed in this study by mixing coal fly ash, which is a by-product of coal electric power plants and blast furnace cement, to increase the specific surface area through pozzolanic reaction. A coal fly ash-blast furnace cement composite was previously reported to be capable of removing H 2 S from both fresh and seawater (Asaoka et al 2012;Asaoka et al 2014;Asaoka et al 2017). However, no data on the removal of H 2 S gas by the coal fly ash-blast furnace cement composite are available.…”