Carbothermal synthesis of aerosol-based iron-carbon nanocomposites for adsorption and reduction of Cr(VI)

Abstract

Spherical iron-carbon nanocomposites were synthesized through a facile aerosol-based process and a subsequent carbothermal reduction. Carbothermal treatment reduces iron species to zero-valent iron rather than using expensive sodium borohydride. In addition, the high porosity of iron-carbon composites allows the entry of contaminants to reactive sites. These composites with nanoscale zero-valent iron particles incorporated in the carbon matrix exhibit synergistic adsorption and reaction for more efficient removal of Cr(VI) in water. Under identical experimental conditions, aerosol-assisted iron-carbon composites showed the highest removal efficiency compared to other materials including nanoscale zero-valent iron particles, aerosol-assisted carbon, and their physical mixture. Meanwhile, X-ray photoelectron spectroscopy analysis proved as-prepared iron-carbon composites could effectively transform Cr(VI) to much less toxic Cr(III). These iron-carbon composites can be designed at low cost, the process is amenable to scale-up for in situ application, and the materials are intrinsically benign to the environment.