Iron-based nanoparticles prepared from yerba mate extract. Synthesis, characterization and use on chromium removal

GARCÍA, FABIANA E.; SENN, ALEJANDRO M.; MEICHTRY, JORGE M.; SCOTT, THOMAS B.; PULLIN, HUW; LEYVA, ANA G.; HALAC, EMILIA B.; RAMOS, CINTHIA P.; SACANELL, JOAQUÍN; MIZRAHI, M.; REQUEJO, FÉLIX G.; LITTER, MARTA I.

JOURNAL OF ENVIRONMENTAL MANAGEMENT

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 2019 vol. 235 p. 1 - 8

0301-4797

Iron-based nanoparticles were synthesized by a rapid method at room temperature using yerba mate (YM) extracts with FeCl3 in different proportions. Materials prepared from green tea (GT) extracts were also synthesizedfor comparison. These materials were thoroughly characterized by chemical analyses, XRD, magnetization, SEMEDS, TEM-SAED, FTIR, UV ?Vis, Raman, Mössbauer and XANES spectroscopies, and BET area analysis. It wasconcluded that the products are nonmagnetic iron complexes of the components of the extracts. The applicabilityof the materials for Cr(VI) (300 μM) removal from aqueous solutions at pH 3 using two Cr(VI):Fe molar ratios(MR), 1:3 and 1:0.5, has been tested. At Cr(VI):Fe MR = 1:3, the best YM materials gave complete Cr(VI) removal after two minutes of contact, similar to that obtained with commercial nanoscale zerovalent iron (N25),with dissolved Fe(II), and with a likewise prepared GT material. At a lower Cr(VI):Fe MR (1:0.5), although Cr(VI)removal was not complete after 20 min of reaction, the YM nanoparticles were more efficient than N25, GTnanoparticles and Fe(II) in solution. The results suggest that an optimal Cr(VI):Fe MR ratio could be reachedwhen using the new YM nanoparticles, able to achieve a complete Cr(VI) reduction, and leaving very low Cr andFe concentrations in the treated solutions. The rapid preparation of the nanoparticles would allow their use inremoval of pollutants in soils and groundwater by direct injection of the mixture of precursors.