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Bivalve shells (Corbula trigona) as a new adsorbent for the defluoridation of groundwater by adsorption-precipitation.

Yapo, N’Zébo Sylvestre, Briton, Bi Gouessé Henri, Aw, Sadat, Reinert, Laurence, Drogui, Patrick ORCID: https://orcid.org/0000-0002-3802-2729 et Adouby, Kopoin (2021). Bivalve shells (Corbula trigona) as a new adsorbent for the defluoridation of groundwater by adsorption-precipitation. Journal of Environmental Science and Health, Part A , vol. 56 , nº 6. p. 694-704. DOI: 10.1080/10934529.2021.1917937.

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Résumé

Defluoridation of groundwater was performed in a batch reactor using bivalve shell powder (BSP) as adsorbent. The physicochemical characteristics of BSP, studied by Fourier Transform Infrared, X-ray Diffraction and Inductively Coupled Plasma-Optical Emission Spectrometry after dissolution, have shown that BSP was mainly composed of crystalline CaCO₃ (∼97.8%). The effects of pH, initial fluoride concentration, adsorbent dose and contact time on the adsorption capacity of BSP were investigated. For an initial fluoride concentration of 2.2 mg/L and with 16 g/L of BSP, after 8 hours of treatment, 27.3% were eliminated at pH 7.5 versus 68% at pH 3, highlighting the efficiency of the adsorption process. The difference in adsorption capacity as a function of pH was correlated to the pHpzc of the BSP, which was equal to 8.2. Thus, at pH below pHpzc, electrostatic attraction between the fluoride anions and the positively charged adsorbent could justify the adsorption mechanism. Fittings of experimental data have evidenced that the adsorption kinetics were of pseudo-second order whereas the adsorption isotherms were of Langmuir type. The chemical precipitation of calcium fluoride was also revealed to occur upon release of Ca²⁺ from partial dissolution of CaCO₃ in acidic conditions.

Type de document: Article
Mots-clés libres: groundwater; fluoride; bivalve shells; adsorption; precipitation
Centre: Centre Eau Terre Environnement
Date de dépôt: 15 oct. 2021 18:17
Dernière modification: 15 févr. 2022 16:43
URI: https://espace.inrs.ca/id/eprint/11992

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