Magnetic Hydrochar (MHC) nanocomposite obtained from sunflower husk (SFH)

AURA ALEJANDRA BURBANO PATIÑO; VERÓNICA LASSALLE; FERNANDA HORST

Fukuoka

Conferencia; 9th International Conference on Nanostructures, Nanomaterials and Nanoengineering (ICNNN 2020); 2020

The oil industry in Argentina produces just over 1.25 million Mg year-1 ofsunflower oil, leaving 600000 Mg year-1 of shell residue. This shell residue can betransformed into hydrochar by hydrothermal carbonization where the biomass istreated at different conditions of temperature, pressure and residence time that willconduct to a material with particular chemical and physical properties. This methodhas attracted attention because it operates at relatively low temperatures ≈100-300 °C(compared to pyrolysis) and autogenous pressure. Furthermore, the hydrochar can bemodified by adding iron oxides (Fe3O4, Fe2O4) on its surface. The incorporation of thisinorganic oxides would be useful due to the magnetic properties acquire by thematerial, so this could be removed from the aqueous media easily, by an externalmagnetic field. The magnetic properties of magnetic hydrochars materials represent anadvantage because it could be possible to overcome some of the conventionaldifficulties when working with hydrochars that include centrifugation, filtration, andbottleneck problem.This study aimed to obtain an industrial waste-based magnetic hydrochar (MHC) byhydrothermal carbonization (HTC) method using 150 °C, 3 hours and H3PO4 as theactivating agent. Sunflower Husk (SFH) is a highly important residue in Argentina,especially in Buenos Aires province and it was used as the feedstock to obtain thehydrochar. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy(SEM), X-ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR),Brunauer-Emmett-Teller (BET), elemental analysis, Dynamic Light Scattering (DLS)and zeta potential were implemented to characterized the synthesized materials.Characterization results showed a successful obtainment of the MHC. BET surface22area and pore volume of the hydrochar are found to be 150 m2/g and 0.19 cm3/grespectively. The carbon content of the hydrochar reached a value of 69%.Furthermore, TEM analysis provided information on the morphology and size particleshowing a stabilization of magnetite nanoparticles by hydrochar matrix as it can beseen in Figure 1 and exhibiting a size which is around 20 nm. Besides, thediffractograms show a crystalline phase owing to magnetite and an amorphous phasedue to the hydrochar. For MHC material, the mechanism of interaction betweenhydrochar and the iron oxide moieties was studied where it was suggested anelectrostatic interaction. Furthermore, a stability test in water was carried out in termsof iron leaching, resulting in a negligible value. This test was important because thematerials might be used in water remediation on the adsorption of organic pollutantsfrom water especially those called emergent pollutants such as pharmaceutic, dyesamong others.