Facile synthesis of reusable magnetic Fe/Fe3C/C composites from renewable resources for super-fast removal of organic dyes: Characterization, mechanism and kinetics

Abstract

Hierarchically structured Fe/Fe3C-carbon composites materials with highly dispersed Fe/Fe3C magnetic nanoparticles have been successfully fabricated via a facile pyrolysis from renewable resources. The high surface area material (1779.3 m2 g−1) has major mesopore distribution centered at 2–4 nm, exhibiting super-fast adsorption and efficient catalytic degradation of organic dyes within 5 min, i.e., methylene blue (Qe,exp = 531 mg g−1), methy red (Qe,exp = 500 mg g−1), malachite green (Qe,exp = 500 mg g−1) and methy orange (Qe,exp = 500 mg g−1). Detailed characterization and mechanism shows that the super-fast removal ability is ascribed to the stronger electrostatic interaction between Fe/Fe3C/C composites and dye, and the breaking of chromophore group though the redox reaction. Particularly, the adsorption isotherm of methylene blue in aqueous solution follows a Langmuir isotherm model at an adsorption capacity of up to 641.0 mg g−1 at 298 K. In view of the abundance and low-cost of walnut shell and iron salt, together with the facile synthesis methodology, the materials reported here are sustainable and promising for practical applications in removing dyes.