Síntese, caracterização e atividade catalítica do Fe3O4@WO3/SBA-15 na fotodegradação do ácido diclorofenoxiacético (2,4-D) sob a irradiação ultravioleta

Abstract

The dichlorophenoxyacetic acid (2,4-D) is a herbicide widely used in agriculture extensive, by present properties that inhibits the proliferation of certain weeds. 2,4-D is toxic to humans and animals, as well as to generate contamination of soils and water resources. In this context, heterogeneous photocatalysis has attracted a lot of attention regarding the process of remediation and degradation of pollutants harmful to the environment. This work aims to synthesize, characterize and evaluate the catalytic activity of Fe3O4@WO3/SBA-15 nanostructured material in the photodegradation of (2,4-D) under ultraviolet irradiation. The magnetite was obtained by the co-precipitation method, the core-shell (Fe3O4@WO3) and the tungsten trioxide (WO3) by solvotermal route, while the mesoporous molecular sieve of the SBA-15 type, and the nanomaterial Fe3O4@WO3/SBA-15 were synthesized by the hydrothermal method. Low-angle X-ray diffractograms showed that the insertion of Fe3O4@WO3 into SBA-15 (5, 10 and 20%) did not destroy the support structure, while the mid-angle diffractograms of the nanomaterials indicated the characteristic planes of each sample and the refinement routine Rietvelt indexed its phases. With the Raman spectroscopy of the Fe3O4 sample, it was possible to observe the presence of bands at 212 and 271 cm -1 characteristic of the hematite phase, besides bands at 133, 272, 326, 716 and 804 cm -1 referring to the monoclinic phase of WO3 according to the standard (ICDS-No. 50727). The morphology was confirmed by micrographs (SEM, MET and HRTEM) as well as the mean particle size for WO3 = 35.8 nm and Fe3O4 = 13.3 nm. The textural parameter nanomateiras point occurred functionalization of SBA-15 with the core-shell. As for optical parameters, they revealed that the energy gap of nanomaterials are in agreement with the literature. Catalytic tests showed significant results, reaching 90.73% degradation of 2.4- D in 240 minutes for the Fe3O4@WO3/SBA-15 nanomaterial (5%).