Magnetic Biochar Obtained by Chemical Coprecipitation and Pyrolysis of Corn Cob Residues: Characterization and Methylene Blue Adsorption

Abstract

Biochar is a carbonaceous and porous material with limited adsorption capacity, which increases by modifying its surface. Many of the biochars modified with magnetic nanoparticles reported previously were obtained in two steps: first, the biomass was pyrolyzed, and then the modification was performed. In this research, a biochar with Fe3O4 particles was obtained during the pyrolysis process. Corn cob residues were used to obtain the biochar (i.e., BCM) and the magnetic one (i.e., BCMFe). The BCMFe biochar was synthesized by a chemical coprecipitation technique prior to the pyrolysis process. The biochars obtained were characterized to determine their physicochemical, surface, and structural properties. The characterization revealed a porous surface with a 1013.52 m2/g area for BCM and 903.67 m2/g for BCMFe. The pores were uniformly distributed, as observed in SEM images. BCMFe showed Fe3O4 particles on the surface with a spherical shape and a uniform distribution. According to FTIR analysis, the functional groups formed on the surface were aliphatic and carbonyl functional groups. Ash content in the biochar was 4.0% in BCM and 8.0% in BCMFe; the difference corresponded to the presence of inorganic elements. The TGA showed that BCM lost 93.8 wt% while BCMFe was more thermally stable due to the inorganic species on the biochar surface, with a weight loss of 78.6%. Both biochars were tested as adsorbent materials for methylene blue. BCM and BCMFe obtained a maximum adsorption capacity (qm) of 23.17 mg/g and 39.66 mg/g, respectively. The obtained biochars are promising materials for the efficient removal of organic pollutants.

Green technology: synthesis of iron-modified biochar derived from pine cones to remove azithromycin and ciprofloxacin from water

“…Lastly, a peak in the 3,632 cm −1 region signifies the presence of OH alcoholic and phenolic stretching. (Yi et al, 2020;Janu et al, 2021;Guel-Nájar et al, 2023). Moreover, the appearance of the band at approximately 529-552 cm −1 in Fe-modified biochar could be assigned to the stretching of the (Fe-O) vibration, showing it to be a magnetized material (Burbano et al, 2023).…”

“…In biochar and Fe-modified biochar, a peak at 31.9 °and 50.8 due to silicon oxide (SiO 2 ) can be observed, respectively (Din et al, 2021a). SiO 2 is a compound that is prominent in the inorganic components of plant-based organic biomass (Guel-Nájar et al, 2023). It has been reported that pine trees have approximately 0.08-1.37 wt% of dry-weight silica in the needles and cones, depending on their family (Assefi et al, 2015).…”

Properties and Possibilities of Using Biochar Composites Made on the Basis of Biomass and Waste Residues Ferryferrohydrosol Sorbent

“…Researchers [ 98 ] developed a biochar composite containing Fe 3 O 4 particles, which was characterized by a maximum MB adsorption capacity of 39.66 mg g −1 . The sorption capacity of unmodified biochar was slightly lower and amounted to 23.17 mg g −1 .…”