Adsorptive removal of methyl blue dye through magnetically retrievable BaFe₁₂O₁₉-activated charcoal-chitosan composite powder: kinetics, isotherms and thermodynamics studies

ABSTRACT

BaFe₁₂O₁₉ (BaM) hexaferrite was synthesised through the coprecipitation method. BaFe₁₂O₁₉-activated charcoal-chitosan (BaM-AC-CS) composite was synthesised through ultra-sonication assisted water in the oil microemulsion method. Morphology of BaM hexaferrite, activated charcoal, and BaM-AC-CS composite powder was evaluated using FESEM. The average particle size of the composite powder was 60 µm. BaM-AC-CS composite powder exhibited a surface area of 41.5 m² g ⁻¹ and pore volume of 0.041 cm³ g⁻¹. The magnetic behaviour of BaM and BaM-AC-CS composite was analysed using a vibrating sample magnetometer. Pure BaM ferrite showed saturation magnetisation (M_s) of 69.3 emu g ⁻¹ and coercivity of 2670 Oe. BaM-AC-CS composite powder showed a M_s value of 26.8 emu g ⁻¹ which was sufficient for efficient magnetic separation of it in water suspension. The point of zero charge (pH_pzc) of composite powder was 6.7. The composite powder was used for the adsorption of methyl blue (MB) dye solution of pH of 6 at 303, 313 and 323 K respectively. The dye removal capacity increased with increase in temperature. The adsorption process followed pseudo-second-order kinetic model and satisfied Redlich-Peterson as well as Sips adsorption isotherm. The composite powder showed a maximum Sips adsorption ability of 254.6 mg g ⁻¹ at 323 K temperature. The free energy and enthalpy changes confirmed the spontaneous and endothermic nature of the adsorption. The composite powder also showed good adsorption capacity in five consecutive regeneration cycles. All these results suggest that the BaM-AC-CS powder will be a viable material for MB dye adsorption in wastewater treatment.

KEYWORDS:

• BaFe₁₂O₁₉
• activated charcoal
• chitosan
• coprecipitation synthesis
• methyl blue
• adsorption

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03067319.2022.2128790

Additional information

Funding

This research was financially supported by the National Institute of Technology, Rourkela, India.