A novel magnetic adsorbent from activated carbon fiber and iron oxide nanoparticles for 2,4-D removal from aqueous medium

ABSTRACT

Carbonaceous materials have been widely applied as adsorbents, but there are some factors that affect their efficiency. In this context, advances in nanotechnology provide new and more efficient methodologies for water treatment. This study evaluated the efficiency of a novel carbon-based adsorbent developed from Brazilian polyacrylonitrile textile fiber and functionalized with iron oxide magnetic nanoparticles for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from the aqueous medium. The synthesized adsorbent (ACF-Fe₃O₄) was characterized by FTIR, XRD, VSM, Zeta potential, SEM, EDX, and TEM. The characterization techniques showed that the adsorbent has peaks characteristic of its precursors and superparamagnetic characteristics, confirming the efficiency of the synthesis method. The adsorption tests evaluated the influence of adsorbent dosage, pH of the contaminant solution, contact time and temperature on the removal of 2,4-D. The experimental data were better adjusted by the pseudo-second order kinetic model and by the Langmuir isothermal model. The thermodynamic parameters revealed that the process is exothermic, spontaneous and thermodynamically favorable. Under the best experimental conditions, the maximum adsorption capacity obtained was 51.10 mg g⁻¹ with an adsorbent concentration of 0.33 g L⁻¹, natural pH of the solution, temperature of 288 K at the equilibrium time of six hours. Adsorbent reusage was studied in four desorption cycles. The adsorption mechanism can be explained through π-π bonds, hydrogen bonds and electrostatic interactions. The prepared material presented high-efficiency adsorption capacity of 2,4-D compared to other carbonaceous materials present in the literature, demonstrating its viability for the removal of this contaminant from the aqueous medium.

GRAPHICAL ABSTRACT

KEYWORDS:

• 2,4-dichlorophenoxyacetic acid
• activated carbon fiber
• adsorption
• iron oxide magnetic nanoparticles
• water treatment

Acknowledgments

This work was supported by the National Council for Scientific and Technological Development (CNPq) and Coordination of Improvement of Higher Education Personnel (CAPES).

Disclosure statement

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

Data availability statement

The authors declare that the data supporting the findings of this study were obtained by experiments carried out by the authors themselves. All the data obtained are available within the article.

Additional information

Funding

This work was supported by the National Council for Scientific and Technological Development (CNPq) and Coordination of Improvement of Higher Education Personnel (CAPES).