Effects of calcination temperature on morphological and crystallographic properties of oyster shell as biocidal agent

Abstract

To develop biocompatible antimicrobial agent, oyster shell wastes were thermally calcined at different temperatures ranging from 300 to 1000 °C. The chemical compositions and properties of oyster shells were characterized. As such, crystallographic analysis presented that oyster shells had a hexagonal crystalline shape, and calcination process reduced their crystalline size, volume (grain dimension), and bond length, which strongly affected antimicrobial efficacy. Results showed that the main components of uncalcined and calcined oyster shells were CaCO3 and CaO, by which CaO was found to be the main antimicrobial component. Notably, calcined oyster shells showed antimicrobial potency against both Gram‐negative (Escherichia coli) and Gram‐positive (Staphylococcus aureus). Furthermore, cytotoxicity analysis proved that calcined oyster shells had good cell viability and low cytotoxicity. Results highlighted that calcined oyster shells, particularly those treated at 750°C, could be a biocompatible alternative to synthetic biocidal and antimicrobial agents using in food packaging, biomedical, and cosmetic industries.

Coupling of Steam and CaO Derived from Oyster Shells in the Pyrolysis of Waste Poly(ethylene terephthalate) for the Selective Production of Aromatic Hydrocarbons

“…The peaks near 2927, 1785, 1080, and 788 cm –1 corresponded to the stretching vibrations of C–H, C = O, C–O–C, and C–C, while peaks at 3426, 2530, and 1645 cm –1 were attributed to O–H/N–H stretching vibrations, S–H stretching vibrations, and N–H bending vibrations, unveiling the presence of organic substances such as proteins and polysaccharides in the oyster shells. , The thermal decomposition process of oyster shells primarily included two stages (Figure b). In the first stage of 100–600 °C, a weight loss of 3.07% occurred, which was mainly attributed to the decomposition of the organic matter . The significant loss of 42.41% between 600 and 800 °C was primarily due to the decomposition of inorganic carbonates …”

“…In the first stage of 100−600 °C, a weight loss of 3.07% occurred, which was mainly attributed to the decomposition of the organic matter. 33 The significant loss of 42.41% between 600 and 800 °C was primarily due to the decomposition of inorganic carbonates. 34 3.1.2.…”

“…The significant peaks at 1473, 857, and 713 cm −1 were attributed to stretching vibrations of CO 3 2− because of abundant inorganic carbonates, mainly CaCO 3 . 33 The peaks near 2927, 1785, 1080, and 788 cm −1 corresponded to the stretching vibrations of C−H, C = O, C−O−C, and C−C, while peaks at 3426, 2530, and 1645 cm −1 were attributed to O−H/N−H stretching vibrations, S−H stretching vibrations, and N−H bending vibrations, unveiling the presence of organic substances such as proteins and polysaccharides in the oyster shells. 34,35 The thermal decomposition process of oyster shells primarily included two stages (Figure 2b).…”

The Effects of Calcination on Mineral Composition and Physical Properties of Limestones and Oyster Shells Derived from Different Sources

“…The calcination process of oyster shells was completed in a shorter time and at a lower temperature than limestones (Ha et al, 2019). The optimum calcination temperature for limestones and oyster shells was about 900°C and 750°C, respectively, which was the temperature performed in traditional limekilns (Moropoulou et al, 2001;Park et al, 2021). According to Ha et al (2019), the texture of calcite in limestones and oyster shells is more important than their chemical compositions that control the calcination temperature and specific surface area of the calcination products (Ha et al, 2019).…”

Calcined waste shells as a promising, eco‐friendly adsorbent, antimicrobial, food preservative, and food packaging material: A mini review

“…Production of ROS (e.g., OH·, ·O 2 , and H 2 O 2 ) is another antimicrobial mechanism of calcined shell powder (Chen et al, 2015; Park et al, 2021; Sadeghi et al, 2020). OH· is a strong oxidant that can damage biomacromolecules.…”