Chromium (III) occurs naturally and has low toxicity, while chromium (VI), which is found in the form of Cr2O72-, comes mainly from industrial chemical processes, being toxic and carcinogenic. Several materials have been developed focusing on the removal of chromium species aiming, above all, at lower cost and greater effectiveness. Among these materials, magnetic coal (CM) stands out, which is obtained through hydrothermal carbonization (CHT) of biomass containing carbon and iron salts and the synthesized material has great chemical stability and easy recovery in water, as well as resistance to acid iced or basic media and high temperatures and pressures. In this study, the CM will be synthesized through the CHT of sugarcane bagasse in the presence of iron nitrate solution (III), at 230 and 270ºC. The CM produced will be submitted to chemical activation processes with KOH (1:2, m:m) and thermal activation in atmosphere of N2 (700ºC). Activated and unactivated materials will be characterized as to their composition, porosity, structure, morphology and magnetic response. In addition, the different materials will be evaluated as adsorbents of chromium species in aqueous solution, by means of a batch adsorption study, to verify the effect of the activation of the material, the determination of chromium (VI) concentration by ultraviolet/visible spectroscopy using the diphenylcarbazide and total chromium method by atomic absorption spectroscopy with graphite furnace atomization (GFAAS) was performed, obtaining the chromium (III) concentration by the difference between total chromium and chromium (VI). The adsorption isotherms will be evaluated by the mathematical models of Langmuir and Freundlich.
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