Hierarchically structured Fe/Fe3C-carbon composites materials with highly dispersed Fe/Fe3C magnetic nanopartides have been successfully fabricated via a facile pyrolysis from renewable resources. The high surface area material (17793 m(2) 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 (Q(e,exp) = 531 mg g(-1)), methy red (Q(e,exp) = 500 mg g(-1)), malachite green (Q(e,exp) = 500 mg g(-1)) and methy orange (Q(e,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. (C) 2019 Elsevier B.V. All rights reserved.