Synthesis of Fe3O4/C composites derived from cornstalk by one-step hydrothermal method as a reusable adsorbent for dyes

Abstract

The magnetic reusable Fe3O4/C composites were prepared derived from agriculture waste cornstalk and ferric nitrate through one-step hydrothermal method. In the preparation process, ferric nitrate was used as not only source of Fe3O4 but also catalyst to promote the generation of carbon nanomaterials from cornstalk avoiding the use of alkali agents and high temperature. The effect of hydrothermal temperature on the crystallite structure and size, magnetic property, adsorption activity of Fe3O4/C composites were mainly investigated. And, the adsorption kinetics and reusability of Fe3O4/C composites were studied. The result showed that the magnetic property increased with the increase of hydrothermal temperature due to the generation of Fe3O4 nanoparticles. Meanwhile, Fe3O4 nanoparticles improved the exfoliation of carbon nanosheets resulting in the increase of the specific surface areas and decrease of the active adsorption sites. Due to both effect of the specific surface areas and active adsorption sites, the adsorbed amount of Fe3O4/C composite increased while the removal rate decreased with the increase of hydrothermal temperature. All Fe3O4/C composites exhibited good adsorption performance to MB and RhB dyes. The removal rate of MB on Fe3O4/C composite with optimum hydrothermal temperature was about 56 % after five cycles, exhibiting good reusability.