Tuning the adsorptive properties of biosynthesized a-Fe2O3 nanoparticles through Nb doping for diuron removal.
FERREIRA, Adriana das Merces Pereira; MARTINS, Walinson Ferreira; MARQUES, Gleison Neres; FERREIRA, Davi Souza; BERNARDI, Maria Inês Basso; SILVA, Elson Longo da; SALES, Lucia Helena Mascaro; ASSIS, Marcelo de; RANGEL, José Hilton Gomes.
FERREIRA, Adriana das Merces Pereira; MARTINS, Walinson Ferreira; MARQUES, Gleison Neres; FERREIRA, Davi Souza; BERNARDI, Maria Inês Basso; SILVA, Elson Longo da; SALES, Lucia Helena Mascaro; ASSIS, Marcelo de; RANGEL, José Hilton Gomes.
Abstract: Pure a-Fe2O3 (H-0) and Nb-doped nanoparticles containing 1% (H-1), 3% (H-3), and 5% (H-5) of Nb5+ were synthesized through a green sol-gel route using Syzygium cumini leaf extract as a natural chelating and polymerizing agent. Structural and morphological analyses confirmed the successful incorporation of Nb into the a-Fe2O3 lattice without secondary phase formation. Nb addition induced local distortions that impact the defect generation, morphology, and size. The samples were evaluated as adsorbents for diuron (0.1-0.5 mg L-1), and the kinetic results showed that all doped samples were better described by the pseudo-second-order model, with H-5 exhibiting the highest rate constants and the strongest evidence of chemisorption-controlled uptake. Equilibrium analyses show that the H-5 sample fits the Langmuir and Freundlich models, indicating a well-distributed set of active sites, whereas the H-3 sample aligns more closely with the Temkin model, suggesting a broader distribution of interaction energies due to its higher surface area. Statistical correlation analysis indicated that Nb doping enhances chemisorption efficiency by increasing pore accessibility and generating reactive defect sites. The H-5 sample exhibited the strongest relationship between Nb content, pore widening, and k2 (pseudo-second-order equilibrium constant), confirming that adsorption is governed by Nb-induced electronic and structural defects rather than by textural parameters. In addition, the recyclability tests demonstrated that the material maintains good stability, with removal efficiency decreasing only slightly from 88.49% to 86.4% after four consecutive cycles, reinforcing its potential for practical applications. These findings show that Nb doping can be effectively integrated into the
@article={003299292,author = {FERREIRA, Adriana das Merces Pereira; MARTINS, Walinson Ferreira; MARQUES, Gleison Neres; FERREIRA, Davi Souza; BERNARDI, Maria Inês Basso; SILVA, Elson Longo da; SALES, Lucia Helena Mascaro; ASSIS, Marcelo de; RANGEL, José Hilton Gomes.},title={Tuning the adsorptive properties of biosynthesized a-Fe2O3 nanoparticles through Nb doping for diuron removal},journal={Materials Chemistry and Physics},note={v. 358, p. 132466-1-132466-15},year={2026}}