Magnetic iron oxide-activated carbon nanocomposite synthesized using Mucuna bracteata leaf extract for Methylene Blue removal: Mechanistic insights into adsorption and phytotoxicity assessment.

Environmental contamination by dye containing waste water poses significant water treatment challenges. Removal of the dye necessitates the development of nanomaterial for water remediation. In the current study, a magnetic iron oxide-activated carbon nanocomposite was synthesized using aqueous Mucuna bracteata extracts, and its Methylene Blue dye removal mechanism was investigated along with phytotoxicity of the treated dye. SEM analysis exhibited the formation of nanosized magnetic iron oxide particles deposited with activated carbon, size ranging from 94.18 to 152.0 nm. The UV-Vis spectrophotometric analysis of Mucuna bracteata leaf extracts indicated the presence of phytochemicals. XRD analysis endorses the crystalline magnetic iron oxide in the nanocomposite, with diffraction peak at 2θ = 35.5°. FTIR analysis revealed the adsorption mechanism of dye removal. The effect of temperature, pH, dosage, concentration, and contact time on the adsorption of Methylene Blue dye on the surface of the magnetic iron oxide-activated carbon nanocomposite was studied. The column studies were also carried out in a packed bed column. The maximum capacity of Methylene Blue adsorption was 109.89 mg/g. The isotherm and kinetic studies of Methylene Blue adsorption exhibited good agreement with the Freundlich (R2 = 0.9591) and pseudo-second-order models (R2 = 0.9749), respectively. The germination results using Trigonella foenum graecum demonstrated 90% of seed germination and improved seedling development due to the reduced phytotoxicity in the eluate. These findings demonstrated that the nanocomposite is an efficient and sustainable adsorbent for the dye contaminated waste water treatment.