Towards advanced industrial waste-based magnetic activated carbons with tunable chemical, textural and magnetic properties

Abstract

The control of chemical, morphological, textural and magneticproperties developed in magnetic activated carbons (MACs) from industrial food waste, was achieved. The process parameters involved in a sustainable and optimized one-step activation route, based on the circular economy model, played an important role and its influence was studied, offering interesting and outstanding results. Magnetite crystalswere formed on the MACs surface obtained from 400 °C to 800 °C while other iron species, such as metallic iron and iron carbides, wereformed only at 800° C. Acid washing favored the mineral matter removal and the presence of iron species was drastically reduced in acid-washed MACs, mainly the iron species originated at 800 °C. Water-washed MACs presented better magnetic response at high temperatures (confirmed by XRD, FTIR, Raman, Mössbauer spectroscopy and VSM characterization techniques). High BET surface area (≈ 822 m2/g) and a large micropore volume (≈ 0.30 cm3/g), were reached by acid washed MACs at 800 °C. Theobtained MACs were fundamentally microporous, but some mesoporosity was also observedwhenactivating agent/precursor mass ratio (1:1) is used. It can be concluded that a MACs strategic design was reached with the objective of removing specific pollutants in multiple environmental applications.