Use of magnetic nanoparticle loaded functionalized multi-walled carbon nanotubes for effective removal of Maxilon red GRL from aqueous solutions

Abstract

In this study, acid-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) were synthesized by subjecting them to acid treatment and subsequently incorporating magnetite (Fe₃O₄) nanoparticles onto their surface (MWCNTs-COOH/Fe₃O₄) through co-precipitating Fe²⁺ and Fe³⁺ in the MWCNTs-COOH colloidal suspension. These were then subjected to comprehensive characterization using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller surface area analysis (BET), and Vibrating sample magnetometer (VSM). The adsorption efficiency of the synthesized MWCNTs-COOH/Fe₃O₄ nanocomposite for the removal of Maxilon Red GRL dye (MR GRL) from aqueous solutions was examined under various conditions, including initial MR GRL concentration (50–250 mg/L), solution pH (2–12), adsorbent dose (0.1–1.0 g/L), and temperature (25–55 °C). Results indicated that the MWCNTs-COOH/Fe₃O₄ nanocomposites displayed strong adsorption capabilities for MR GRL in aqueous solutions, and the adsorption process adhered to the Langmuir isotherm model. Kinetic adsorption data were well-fitted to the pseudo-second-order model. At the natural pH of 5.8 and a temperature of 25 °C, the adsorption capacity and removal percentage were determined as 188.68 mg/g and 97%, respectively. The adsorption of MR GRL onto MWCNTs-COOH/Fe₃O₄ was endothermic and spontaneous, according to thermodynamic characteristics. These findings indicate the potential of the newly synthesized adsorbent in advancing water purification through effective adsorptive separation.

Graphical Abstract