Changes in physical and chemical characteristics and reactivity to hydrogen sulfide of calcined oyster shells

Influence of Oyster Shell Pyrolysis Temperature on Sediment Permeability and Remediation

“…Recent studies have reported that calcium-based materials increase soil permeability because of the flocculation of clayey particles and prevent blockage of soil porosity [16,17]. Similar results were obtained in the present study; the permeability of POS600-covered sediments is greater than that of POS350-covered and sand-covered sediments, because of a higher percentage of CaO in oyster shells pyrolyzed at temperatures above 500 • C, which is the source of Ca 2+ [19].…”

“…Comparatively more Ca 2+ was found in the POS600: 53.9 µg/g after 6 h and 54.1 µg/g after 24 h. Results indicate that the concentration of Ca 2+ increased along with an increased temperature of pyrolysis. This result is due to the fact that pyrolysis of oyster shells below 350 • C does not generate CaO [9], whereas, above 500 • C, CaCO 3 is converted to CaO [19], which is the source of Ca 2+ [18].…”

“…Oyster shells are composed of over 95% CaCO 3 , an eco-friendly material that can supply Ca 2+ to the ocean [18]. The chemical compositions of oyster shells change; the primary component of oyster shells, CaCO 3 , transforms into calcium oxide (CaO) at temperatures above 500 • C [19]. Numerous studies have proven that the removal of nutrients and heavy metals from oyster shells calcined at 600 • C or above has a positive impact on the environment [20,21].…”

“…Oyster shells that have pyrolyzed at different temperatures have been shown to have an effect on both their chemical properties and sediment remediation [9][10][11][19][20][21]. However, its effect on permeability performance still has relevance, and further research is required for a better understanding of this phenomenon.…”

Effect of chemical composition of coal ash used to prepare granulated coal ash on the removal of hydrogen sulfide from water

“…However, whereas most studies have investigated the removal of hydrogen sulfide gas, only a handful have focused on the removal of liquid‐phase hydrogen sulfide. In order to remove hydrogen sulfide from water and sediments, adsorbents prepared from coconut shell, palm kernel shell, wood sawdust (Habeeb, Kanthasamy, et al, 2020), waste‐tire‐derived rubber particles (Irfan et al, 2020), δ‐MnO 2 /porous graphitic carbon (Edathil et al, 2021), and calcined oyster shells (Yamamoto et al, 2022) have been proposed. We previously found that hydrogen sulfide in water can be removed from both fresh water and seawater using granulated coal ash (GCA) prepared from coal fly ash obtained from a coal electric power plant and blast furnace cement (Asaoka et al, 2012, 2017).…”