Removal of methylene blue dye by adsorption onto Natural Muscovite Clay: experimental, theoretical and computational investigation

ABSTRACT

The ability of Natural Muscovite Clay (NMC) to adsorb Methylene Blue (MB) as a dye widely used in the industrial sector was investigated, and the adsorption process was interpreted at the molecular scale through computational modelling. After the characterisation of NMC, the effect of adsorbent mass (5–40 mg), contact time (1–60 min), solution pH (3.7-11.78), stirring speed (100–900 rpm), initial MB concentration (15–80 mg.L^-1), and temperature (293.15-333.15 K) on the adsorption efficiency were inspected in the batch mode. The results showed that the basic pH, high stirring speed, and low temperature were the favourable conditions for the MB adsorption onto NMC. The adsorbed quantity Q_e,exp of MB dye was found to be 59.828 mg.g^-1 for the initial concentration of 80 mg.L^-1 at 293.15 K using an NMC mass of 20 mg. The obtained values of thermodynamic parameters suggested that the removal of the MB dye was exothermic, and physical in nature. The adsorption isotherm of the MB/NMC system was analysed according to the statistical physics approach using the Levenberg-Marquardt iterating algorithm and showed a best fitting with the monolayer model with one energy. The analysis of kinetic data showed that the external diffusion and intra-particle diffusion steps have occurred simultaneously and contributed to the control of the adsorption rate of the MB dye onto NMC. The computational modelling of interactions between the MB molecule and the muscovite, kaolinite, and quartz minerals were examined according to the Monte Carlo simulation (MCS) and showed an ability of the dye molecule to be adsorbed onto the surface of these minerals. The calculated adsorption energies ranged between -2.23×10⁴ and -1.10×10⁴ Kcal.mol^-1 reflected the stability and the spontaneity of the adsorption process. So, the surface of clay minerals (i.e. muscovite and kaolinite) was more favourable to the adsorption of the MB molecule.

KEYWORDS:

• Natural MuscoviteClay
• methylene blue
• adsorption
• monte carlo simulation

Acknowledgments

We would like to thank ZakariaNioua, high school teacher at the Moroccan national education ministry, for the linguistic verification of this article.

Author contribution statement

Otheman Amrhar: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Wrote the paper. AvniBerisha: Performed the Monte Carlo Simulation; Interpreted the data. Lahoucine El Gana: Analyzed the data. HakimaNassali: Supervised. Mohamed S.Elyoubi: Supervised.

Disclosure statement

There is no conflict of interest in this work

Supplementary material

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Additional information

Funding

The present work did not receive any specific finance from funding establishment in the public, commercial, or not-for-profit sectors.