Effective adsorption of Fuchsine dye on FeZnOAC: kinetic, isotherm, double-layer modelling and reusability study

ABSTRACT

The FeZnO (iron zinc bimetallic oxide) was synthesised using the ultrasound-assisted method and further converted into FeZnOAC (iron zinc bimetallic oxide-doped activated carbon) by treating it with activated carbon. As developed FeZnOAC is effectively used for the adsorption of Fuchsine dye from an aqueous dye solution. A 200 mg of FeZnOAC was sufficient for the rapid removal of Fuchsine (>97.64%) dye. The kinetic adsorption data is well fitted with a pseudo-second-order model. The Langmuir isothermal model shows a high regression coefficient (R²) than the Freundlich with a Q_max of 333.33 mg g⁻¹. The dye adsorption at varying temperatures (i.e. 298–318 K) was based on a multi-layered statistical physics model. The n value (n < 0.5) obtained from the model indicates that the Fuchsine dye adsorbed on the surface of FeZnOAC is parallel adsorption. It shows that the dye molecules’ adsorptive orientations are dependent on the temperature and nature of the system. The FeZnOAC is proven to be a potential adsorbent for the removal of Fuchsine due to the availability of more adsorption sites. Interestingly, FeZnOAC is used for regeneration studies up to five cycles with a maximum adsorption capacity of 97.4%. The as-synthesised FeZnOAC has been successfully applied to remove Fuchsine dye from industrial wastewater, resulting in an alternative candidate for commercialisation.

KEYWORDS:

• FeZnOAC
• adsorption
• pseudo-second-order model
• Langmuir isotherm
• statistical physics model

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Funding

This work was supported by the Taif University Researchers Supporting Project number (TURSP-2020/04), Taif University, Taif, Saudi Arabia.