Magnetic hydrochar nanocomposite obtained from sunflower husk: A potential material for environmental remediation

Abstract

A novel magnetic hydrochar composed of nanosized magnetite (Fe3O4) particles supported on a hydrochar matrix was synthesized via hydrothermal carbonization of sunflower husk, employing phosphoric acid as the activating agent. An exhaustive characterization of the hydrochars and the magnetic hydrochar was undertaken to identify, mainly, the mechanism by which the iron oxide nanoparticles interact with the hydrochar matrix. The magnetic hydrochar exhibited superparamagnetic properties with a saturation magnetization of 55,21 emu/g. BET surface area and pore diameter of the magnetic hydrochar were found to be 55.25 m2/g and 10,49 nm respectively which are in accordance with mesoporous materials. Fourier transform infrared spectroscopy and z potential characterization suggest that the main mechanisms of interaction between the magnetite nanoparticles and the hydrochar matrix were coulombic ones, where carboxyl and hydroxyl oxygen-containing functional groups of the hydrochar were more likely to interact with the iron oxide nanoparticles.