Efficiency of natural clay and titania P25 composites in the decolouring of methylene blue (MB) from aqueous solutions: dual adsorption and photocatalytic processes

In this paper, we use Tunisian clay materials as alternative low-cost adsorbents, as well as substrates to immobilise TiO 2 for the decolouration of methylene blue (MB) dye solutions. The collected raw clay from the mine of Tamra was characterised by various techniques, such as X-ray diffraction (XR...

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Bibliographic Details
Published in:Arabian journal of geosciences 2021-03, Vol.14 (5), Article 400
Main Authors: Lazaar, Khalil, Chargui, Hajer, Pullar, Robert, Hajjaji, Walid, Moussi, Bechir, Labrincha, João, Rocha, Fernando, Jamoussi, Fakher
Format: Article
Language:English
Subjects:
Adsorption
Aqueous solutions
Clay
Decoloring
Decolorization
Diffraction patterns
Dyes
Earth and Environmental Science
Earth science
Earth Sciences
Electron microscopy
Fluorescence
Kaolinite
Methylene blue
Original Paper
Photocatalysis
Removal
Scanning electron microscopy
Substrates
Titanium dioxide
Ultraviolet radiation
X rays
X-ray diffraction
X-ray fluorescence
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Summary:In this paper, we use Tunisian clay materials as alternative low-cost adsorbents, as well as substrates to immobilise TiO 2 for the decolouration of methylene blue (MB) dye solutions. The collected raw clay from the mine of Tamra was characterised by various techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF). XRD patterns of the raw clay showed halloysite as the main phase (61%), with a lower content of kaolinite (39%). For MB adsorption, the experimental data were fitted by Langmuir and Freundlich adsorption equations. It was found that the studied clays alone were not very efficient at adsorbing MB dye molecules. The decolouration of MB was improved by adding a photocatalytic function to the clay, by adding various amounts of TiO 2 nanopowder (20–80 wt%) to the clay, imbuing it with photocatalytic capabilities. These combined effects of the phenomena of adsorption and photocatalysis for MB removal by the TiO 2 -doped clay resulted in a very satisfactory performance, even with the relatively low quantity of 20 wt% added TiO 2 photocatalyst. This gave 48.6% removal after only 30-min adsorption in the dark, increasing to 84.1% removal after a further 3 h under UV light, through combined chemo-physical adsorption and photocatalytic decolouration phenomena.
ISSN:1866-7511
1866-7538
DOI:10.1007/s12517-021-06727-x