# Biofunctional Magnetic Carbon Nanohybrid for Fast Removal of Methyl Blue from Synthetic Laboratory Effluent

## TL;DR

A new magnetic carbon nanohybrid was developed to efficiently and sustainably remove methyl blue dye from water.

## Contribution

A novel magnetic nanohybrid using Eucalyptus extract was developed for fast and reusable methyl blue removal.

## Key findings

- The nanohybrid achieved a maximum adsorption capacity of 92.9 mg g−1 for methyl blue.
- The material retained over 98% removal efficiency after five regeneration cycles.
- The system successfully removed over 91% of methyl blue from synthetic effluents.

## Abstract

The contamination of aquatic systems by industrial dyes, particularly methylene blue (MB), presents a significant environmental challenge due to their chemical stability and toxicity. In this study, the development and application of a novel magnetic nanohybrid comprising multiwall carbon nanotubes (MWCNTs) functionalized with maghemite (γ-Fe2O3) nanoparticles biosynthesized using Eucalyptus globulus extract (denoted MWNT-NPE) is reported. The material was thoroughly characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Vibrating Sample Magnetometer (VSM), and Fourier-Transform Infrared (FTIR) techniques, revealing high crystallinity, mesoporosity, and superparamagnetic behavior. The MWNT-NPE exhibited exceptional MB adsorption performance under optimized conditions (pH 6, 0.8 g L−1 dose, 40 min equilibrium), achieving a maximum adsorption capacity of 92.9 mg g−1. Kinetic analysis indicated chemisorption and physisorption regimes depending on MB concentration, with the pseudo-second-order and Freundlich isotherm models providing the best fits of experimental data. FTIR spectroscopy demonstrated that the removal mechanism involves π–π stacking, hydrogen bonding, and electrostatic interactions between MB molecules and the composite’s surface functional groups. Notably, the magnetic nanohybrid retained over 98% removal efficiency across five regeneration cycles and successfully removed MB from synthetic effluents with efficiencies exceeding 91%. These findings highlight the synergistic adsorption and magnetic recovery capabilities of the bio-functionalized hybrid system, presenting a sustainable, reusable, and scalable solution for industrial dye remediation.