Síntese verde de nanopartículas de ferro empregando extratos vegetais como agentes redutores e estabilizadores

Abstract

The study aimed at a sustainable approach through the application of green synthesis of iron nanoparticles (Fe(NPs)), utilizing aqueous extracts from mango, eucalyptus, and guava leaves as reducing and stabilizing agents during the process, employing the Fe(NPs) in the catalytic reduction of 4-nitrophenol. The variation in volumetric proportions of the plant extracts and sodium borohydride (NaBH4) was explored to minimize the use of the chemical agent. Thus, assessing how the different volumetric proportions influence the physicochemical and morphological properties of the Fe(NPs). After the syntheses, the characterization of nanoscale materials was conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM/EDS), field emission scanning electron microscopy (FEG), Fouriertransform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). It is noteworthy that Fe(NPs) synthesized with 25% of the extracts exhibited predominant characteristics of lepidocrocite and excellent performance, catalyzing conversions exceeding 90% in the reduction of 4-nitrophenol, due to the smaller particle size. Fe(NPs) synthesized with 40% of guava and eucalyptus extracts also demonstrated notable catalytic performances, accompanied by significant reductions in the use of the chemical agent. The efficacy of these Fe(NPs) is attributed to the vegetal coatings, preventing the formation of metallic ion clusters, higher iron content, and the presence of fissures or pores, characterizing the nanomaterials as efficient adsorbents. Finally, ecotoxicological tests with Artemia salina and Lemna minor were conducted to assess the toxicity of the contaminant (4-nitrophenol) before and after the catalytic reduction process, as well as the leachates from the Fe(NPs) and NaBH4. The results indicated the biocompatibility of the Fe(NPs), the reduction in the toxicity of the contaminant after catalytic reduction, and the high toxicity of NaBH4, emphasizing the need to minimize its use in various processes.