Iron precursor salt effect on the generation of [rad]OH radicals and sulfamethoxazole degradation through a heterogeneous Fenton process using Carbon-Fe catalysts Article uri icon

abstract

  • The influence of the iron precursor salt on the preparation of Carbon-Fe catalysts was evaluated based on the generation of [rad]OH radicals in a heterogeneous Fenton process applied to the degradation of sulfamethoxazole (SMX). Carbon catalysts were obtained with 9%25 Fe by weight using three iron salts: iron acetate (C-AC-AFe), iron sulfate (C-AC-SFe) and iron nitrate (C-AC-NFe). Characterization of catalysts was evaluated by N2 physisorption, X-ray diffraction, scanning electron microscopy and spectroscopic techniques (FTIR, EDX, XPS); these properties were related to the [rad]OH generation kinetics and to SMX degradation rate. The iron precursor salt favors the anchoring of the metal in different oxidation state on the catalyst in a proportion of: Fe2 / Fe3 = 4.1 for C-AC-AFe, 1.5 for C-AC-SFe and 1.7 for C-AC-NFe, which is related to the [rad]OH generated: 53.8 μM g−1, 37.9 μM g−1 and 42.4 μM g−1, respectively. The [rad]OH generation kinetics were described by a pseudo-first-order model with rate constants of 0.0252 and 0.0299 min−1 for C-AC-AFe and C-AC-SFe respectively, which coincide with the kinetic constants for the degradation of SMX (0.0262 and 0.0297 min−1), therefore, the oxidation process is carried out by [rad]OH. In the case of C-AC-NFe, Fe was fixed within the texture of the carbon and the [rad]OH generation was the lowest (0.0005 min−1), explaining the reaction is limited by diffusion. For SMX, the degradation percentage achieved for 20 mg L−1 was: 98.2 %25 in 120 min for C-AC-AFe, 98.1 %25 in 180 min for C-AC-SFe and 92.8 %25 in 210 min for C-AC-NFe. © 2020 Elsevier Ltd
  • The influence of the iron precursor salt on the preparation of Carbon-Fe catalysts was evaluated based on the generation of [rad]OH radicals in a heterogeneous Fenton process applied to the degradation of sulfamethoxazole (SMX). Carbon catalysts were obtained with 9%25 Fe by weight using three iron salts: iron acetate (C-AC-AFe), iron sulfate (C-AC-SFe) and iron nitrate (C-AC-NFe). Characterization of catalysts was evaluated by N2 physisorption, X-ray diffraction, scanning electron microscopy and spectroscopic techniques (FTIR, EDX, XPS); these properties were related to the [rad]OH generation kinetics and to SMX degradation rate. The iron precursor salt favors the anchoring of the metal in different oxidation state on the catalyst in a proportion of: Fe2%2b / Fe3%2b = 4.1 for C-AC-AFe, 1.5 for C-AC-SFe and 1.7 for C-AC-NFe, which is related to the [rad]OH generated: 53.8 μM g−1, 37.9 μM g−1 and 42.4 μM g−1, respectively. The [rad]OH generation kinetics were described by a pseudo-first-order model with rate constants of 0.0252 and 0.0299 min−1 for C-AC-AFe and C-AC-SFe respectively, which coincide with the kinetic constants for the degradation of SMX (0.0262 and 0.0297 min−1), therefore, the oxidation process is carried out by [rad]OH. In the case of C-AC-NFe, Fe was fixed within the texture of the carbon and the [rad]OH generation was the lowest (0.0005 min−1), explaining the reaction is limited by diffusion. For SMX, the degradation percentage achieved for 20 mg L−1 was: 98.2 %25 in 120 min for C-AC-AFe, 98.1 %25 in 180 min for C-AC-SFe and 92.8 %25 in 210 min for C-AC-NFe. © 2020 Elsevier Ltd

publication date

  • 2020-01-01