Efficiency, Kinetics and Thermodynamics of Toluidine Blue Dye Removal from Aqueous Solution Using MWCNTs Decorated with NiFe2O4

• Published in: Fullerenes, nanotubes, and carbon nanostructures nanotubes, and carbon nanostructures, 2014-03, Vol.22 (5), p.454-470
• Main Authors: Bahgat, M., Farghali, A. A., El Rouby, W. M. A., Khedr, M. H.
• Format: Article
• Language: English
• Subjects: Adsorption; Carbon nanotubes; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Decoration; Diffusion in nanoscale solids; Diffusion in solids; Exact sciences and technology; Isotherm; Kinetics and thermodynamics; Materials science; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanotubes; NiFe; Physics; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Toluidine blue; Transport properties of condensed matter (nonelectronic)
• ISSN: 1536-383X; 1536-4046
• DOI: 10.1080/1536383X.2012.684188

NiFe 2 O 4 /Carbon nanotube composite materials have been prepared using in-situ chemical precipitation of metal hydroxides in the presence of multi-walled carbon nanotubes (MWCNTs) and followed by hydrothermal processing. The obtained composite powders were characterized using XRD and TEM. The adsorption efficiency of NiFe 2 O 4 /carbon nanotubes for toluidine blue at various temperatures was examined. The amount adsorbed increased with the NiFe 2 O 4 /CNTs dosage. The linear correlation coefficients and standard deviations of Langmuir and Freundlich isotherms were determined. The results revealed that Langmuir isotherm fitted the experimental results well. Kinetic analyses were conducted using pseudo first-order, second-order and the intraparticle diffusion models. The regression results showed that the adsorption kinetics were more accurately represented by a pseudo second-order model. Changes in the free energy of adsorption (ΔG 0 ), enthalpy (ΔH 0 ) and entropy (ΔS 0 ), as well as the activation energy (E a ) were determined. ΔH 0 and ΔS 0 were 15.99 kJ/mol and 98 J/mol K, respectively. The activation energy was 8.2 kJ/mol. ΔH 0 , ΔG 0 and E a values reflected that the adsorption of toluidine blue onto NiFe 2 O 4 /CNTs was by physisorption.