The effect of carbon coating on the arsenite sorption by magnetic carbon nanocomposites

BURBANO, A. A.; LASSALLE, V. L.; HORST, M. F.; GASCÓ, G.; MÉNDEZ, A.

INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY

CTR ENVIRONMENT & ENERGY RESEARCH & STUDIES

Año: 2024

1735-1472

Arsenic pollution has emerged through anthropogenic activities and natural mineral leaching processes. This study aims toadvance the use of magnetic carbon nanocomposites (MCNs) in the sorption of arsenic, studying the infuence of feedstockand the presence of carbon coating on magnetic nanoparticles. Previous works have shown that post-pyrolysis treatmentimproves the stability of MCNs by reducing iron leaching due to the formation of a carbon coating that encapsulates theiron oxide nanoparticles. However, this carbon coating could infuence the adsorption properties of MCNs. This investigation deals with arsenic adsorption by four MCNs prepared by co-precipitation of magnetite (Fe3O4) nanoparticle into fourcarbonaceous matrixes, followed by a post-pyrolysis treatment. The pristine carbonaceous matrixes used in the present workwere commercial activated carbon (CAC), charcoal (CC), hydrochar from the orange residue (HCOR), and biochar from sunfower husk (BCSFH). Pristine carbonaceous materials and MCNs without post-pyrolyzed were also used as arsenic sorbentsin water solutions. Additionally, kinetic studies were carried out to explore the sorption properties of diferent MCNs andpristine materials, concerning the removal efciencies (expressed as a percentage) and adsorption capacities, determiningthe equilibrium time. The results demonstrated that the presence of magnetite increases the adsorption of arsenic, beinghigher in the case of materials obtained by direct co-precipitation than in materials subjected to a post-pyrolysis process.The presence of a carbon layerprotecting the magnetite slightly decreases the adsorption of arsenic.