Enhanced Malachite Green uptake using chemically-modified reed-based powder: equilibrium, kinetics, mechanism, and reusability

ABSTRACT

Novel bio-adsorbents based on abundant and invasive plants such as reeds represent an original and ecological route for the development of innovative biomaterials. Sustainable, eco-efficient, and facile processes have been suggested to improve the adsorptive performances and physicochemicalproperties of reedparticles. The morphological, textural, and physicochemical characteristics of the prepared reed-based adsorbents, namely untreated reed particles (RP), NaOH-treated RP (NaOH-RP), and sodium dodecyl sulphate impregnated RP (SDS-RP) were assessed by SEM, FTIR, XRD, BET, and TGA/DTG. The adsorptive performances of RP, NaOH-RP, and SDS-RP were evaluated for a triphenylmethane dye (Malachite Green, MG) elimination from water.The experimental results and kinetic models proved the improvement of MG uptake by modified reed-based adsorbents.The maximum MG uptake capacity of NaOH-RP and SDS-RP materials reached 82.64 and 102.88mgg⁻¹, respectively, but it only attaineda value of 75.93mgg⁻¹ for RPat the same conditions. The used reed-based adsorbents can regenerate four times with an MG removal capacity permanently superior to 80%. Besides, their experimental data obeyed the Freundlich equation and the pseudo2^ndorder kinetic model, indicating the heterogeneous multilayer adsorption of MG onto reed-based materials. The adsorption/desorption, kinetic, isotherm, and thermodynamic studies, and physicochemical characterisations revealed that electrostatic interactions might be the governing mechanism of MG dye adsorption onto RP, NaOH-RP, and SDS-RP. Nonetheless, interactions such as H-bonding interactions, π-π stacking interactions, and hydrophobic interactions would also exist.

KEYWORDS:

• Sodium dodecyl sulphate
• mercerisation
• reed
• malachite Green
• adsorbent reusability
• adsorption mechanisms

Acknowledgments

The author (R.B.A.) would like to express her gratitude for the funding support from the Ministry of Higher Education and Scientific Research of Tunisia through the research program (Programme d’encouragement des jeunes chercheurs – 1ère edition - 2017) - (Grant number: 18 PEJC 12-02). The author (A.G.) acknowledgesthe innovative work of all the scholars who have developed green materials, processes, and tools for aqueous media decontamination. Authors are also grateful to Prof. Rim Najjar for her assistance in proofreading this work.

Disclosure statement

On behalf of all authors, the corresponding author states that there is no conflict of interest.

Supplementary material

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Additional information

Funding

This work was supported by the Ministère de l’enseignement Supérieur et de la recherche Scientifique Tunisien [18 PEJC 12-02].