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Improved nanocomposite of montmorillonite and hydroxyapatite for defluoridation of water

Fernando, MS; Wimalasiri, AKDVK; Ratnayake, SP; Jayasinghe, JMARB; William, GR; Dissanayake, DP; de Silva, KMN; (2019) Improved nanocomposite of montmorillonite and hydroxyapatite for defluoridation of water. RSC Advances , 9 (61) pp. 35588-35598. 10.1039/c9ra03981c. Green open access

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Abstract

A novel hydroxyapatite montmorillonite (HAP-MMT) nanocomposite system was synthesized using a simple wet chemical in situ precipitation method. Neat nano hydroxyapatite (HAP) was also synthesized for comparison. The characterization of the materials was carried out using Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) isotherms to study the functional groups, morphology, crystallinity and the surface area respectively. Batch adsorption studies and kinetic studies on fluoride adsorption were conducted for the HAP-MMT system and for neat HAP. The effect of parameters such as contact time, pH, initial concentration, temperature, and thermodynamic parameters and the effect of coexisting ions on fluoride adsorption by HAP-MMT were studied. Results of the isotherm experiments were fitted to four adsorption isotherm models namely Langmuir, Freundlich, Temkin and Dubinin Radushkevich. Fluoride adsorption over HAP-MMT fitted to the Freundlich adsorption isotherm model and showed more than two-fold improved adsorption capacity (16.7 mg g−1) compared to neat HAP. The best-fitting kinetic model for both adsorbents was found to be pseudo second order. Calculated thermodynamic parameters indicated that the fluoride adsorption by HAP-MMT is more favorable compared to that on HAP within the temperature range of 27 °C–60 °C. Improved fluoride adsorption by HAP-MMT is attributed to the exfoliated nature of HAP-MMT. Gravity filtration studies carried out using a 1.5 ppm fluoride solution, which is closer to the ground water fluoride concentrations of Chronic Kidney Disease of unknown etiology (CKDu) affected areas in Sri Lanka, resulted in a 1600 ml g−1 break through volume indicating the potential of HAP-MMT to be used in real applications.

Type: Article
Title: Improved nanocomposite of montmorillonite and hydroxyapatite for defluoridation of water
Open access status: An open access version is available from UCL Discovery
DOI: 10.1039/c9ra03981c
Publisher version: https://doi.org/10.1039/c9ra03981c
Language: English
Additional information: This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. http://creativecommons.org/licenses/by-nc/3.0/
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > UCL School of Pharmacy
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > UCL School of Pharmacy > Pharmaceutics
URI: https://discovery.ucl.ac.uk/id/eprint/10085209
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