Efficiency of natural clay and titania P25 composites in the decolouring of methylene blue (MB) from aqueous solutions: dual adsorption and photocatalytic processes
authors Lazaar, K; Chargui, H; Pullar, R; Hajjaji, W; Moussi, B; Labrincha, J; Rocha, F; Jamoussi, F
nationality International
author keywords Halloysite-rich clay; Titania; Methylene blue; Adsorption; Photocatalysis
abstract In this paper, we use Tunisian clay materials as alternative low-cost adsorbents, as well as substrates to immobilise TiO2 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 TiO2 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 TiO2-doped clay resulted in a very satisfactory performance, even with the relatively low quantity of 20 wt% added TiO2 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
isbn 1866-7538
year published 2021
volume 14
issue 5
digital object identifier (doi) 10.1007/s12517-021-06727-x
web of science category 10
subject category Geosciences, Multidisciplinary
unique article identifier WOS:000625201900001
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