Onion-like magnetic meso-porous carbon surfaces for the efficient adsorption of aqueous crystal violet dye molecules

This study describes novel synthesis of magnetite (Fe₃O₄) nanoparticles (NPs) dispersed in oxidized onion-shaped carbon nanosurface (o-OSCS) for the adsorptive removal of crystal violet (CV) dye compounds from water. The physicochemical characteristics of the synthesized materials are tested by various analytical and spectroscopic techniques. Characterization data confirm successful incorporation of Fe₃O₄ onto o-OSCS. The adsorption of CV onto Fe₃O₄/o-OSCS is found to be dependent on pH of the solution. The maximum adsorption of CV onto Fe₃O₄/o-OSCS is obtained to be 247.51 mg/g at pH 12 and 25 °C. The excellent adsorption of CV is attributed to the combined effects of π–π interactions, hydrogen bonding, electrostatic interactions and pore-filling mechanisms. Owing to the magnetic property (saturation magnetization value = 28.06 emu/g), the material may be separated efficiently from the aqueous medium after adsorption with an external magnet. With proper optimization of synthesis and adsorption parameters, the material may be useful in the removal of several other organic and inorganic pollutants from water.