Adsorption of Textile Dyes on the Shells of Snails iAchatina achatina/iand iLanistes varicus/iAcclimatized in Benin: Influence of Their Heating Treatment

摘要

The characterization of the shells of snails Achatina achatina and Lanistes varicus indicates that they contain calcium carbonate (98%) essentially aragonite, and organic matter (2%). The heating at 500°C during three hours (3 h) has destroyed their constitutive organic matter, converted the aragonite form completely into the calcite and reduced their specific surfaces. The effects of these modifications have been revealed in the adsorption in aqueous environment of methylene blue (MB) and methyl orange (MO) which are respectively cationic and anionic dyes. The results showed that the sorption of these dyes on the raw shells is more important than the heated shells. The methylene blue has more affinity for shells than methyl orange. Between these two types of snails, the shells of Lanistes varicus have a higher capacity of adsorption. This sorption of the methylene blue is more in relationship with the Freundlich model ( for EG and for EA) comparatively to Langmuir model If the shells of these snails were calcined before using for the cicatrizing of the human cutaneous wounds in Benin. In the case of the sorption of organic molecule, it will be necessary to avoid submitting them to a preliminary heat treatment.