Use of magnetic nanoparticles of iron oxide and their derivatives in the adsorption of rhodamine 6G and rhodamine B dyes

• Published in: Journal of alloys and compounds 2024-11, Vol.1005, p.175907, Article 175907
• Main Authors: Damasceno, Barbara Souza, da Silva, Valéria Cristina, Rodrigues, Alexandre Ricalde, Falcão, Eduardo Henrique Lago, Vaz de Araújo, Ana Cláudia
• Format: Article
• Language: English
• Subjects: Adsorption capacity; Magnetic nanoparticle; Physisorption; Rhodamine dye; Water decontamination
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.175907

Rhodamines are cationic dyes widely used in textiles and as laser media, despite their many severe health and environmental hazards. In this work, we have assessed the potential of magnetite and cobalt ferrite nanoparticles (NPs) for removing rhodamines B (Rh B) and 6G (Rh 6G) from aqueous solutions. The magnetite (Fe3O4) NPs were synthesized by the co-precipitation method, while the cobalt ferrite (CoFe2O4) NPs were obtained hydrothermally. The structures of cubic magnetite Fe3O4 and cubic CoFe2O4 were confirmed by XRD and by FTIR and Raman, while the surface morphology checked by SEM showed clusters of polydisperse particles with average diameters around 51.0 nm and 57.0 nm, respectively. These particles presented calculated BET surface areas of 33.8 m2/g (Fe3O4) and 47.3 m2/g (CoFe2O4). Hysteresis curves confirmed the ferromagnetic behavior for both NPs. The point of zero charge was 6.46 for Fe3O4 and 7.16 for CoFe2O4, and using pH 4 in the system, the overall percent removal (%R) were above 80 % for all samples during the uptake of Rh B and 6G. The system Rh 6 G-CoFe2O4 performed better at pH 6 (%R ∼93 %). In all cases, the Elovich and pseudo-second-order (PSO) models were chosen for fitting the kinetic data, and after equilibrium was reached (∼ 30 min), the adsorptive capacities were estimated to be above 138 mg g−1 for all systems. Adsorption isotherms at 301, 311 and 321 K were obtained. Good agreement between the experimental data and the Langmuir, Freundlich and Sips models was observed for Rh 6 G adsorption by both NPs (R2 ≥ 0.90). The Freundlich model was the only one that fitted well the experimental data for Rh B (R2 ≥ 0.90, for all systems). The thermodynamic parameters were also calculated from the isotherm data. •Both Fe3O4 and CoFe2O4 exhibited ferromagnetic behavior.•Fe3O4 and CoFe2O4 exhibited %R above 80 % during the uptake of Rh B.•Fe3O4 and CoFe2O4 exhibited %R above 90 % during the uptake of Rh 6G.•The qe-PSO of Fe3O4 were ∼160 mg g−1 (Rh 6G) and ∼138 mg g−1 (Rh B).•The qe-PSO of CoFe2O4, were ∼159 mg g−1 (Rh 6G) and ∼145 mg g−1 (Rh B).