Magnetic iron species highly dispersed over silica: use as catalysts for removal of pollutants in water

VICTOR A. A. FREITAS; LAURA A. MAIA; ROLANDO E. BELARDINELLI; JOSE D. ARDISSON; MÁRCIO C. PEREIRA; LUIZ C. A. OLIVEIRA

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2016

0944-1344

Fe2O3-SiO2 composites were prepared by impregnation (sample FeIMP) or doping (sample FeDOP) in the structure of porous silica. The dye removal capacity of the materials was investigated through adsorption and oxidation studies of methylene blue and rhodamine B. N2 adsorption/desorption measurements on FeIMP and FeDOP resulted in specific areas of 27 and 235 m2 g−1, respectively. Mössbauer spectroscopy and XRD data detected hematite and maghemite as the iron phases in the samples FeIMP and FeDOP, respectively.Adsorption isotherms and kinetic studies of the dyes were better fitted inDKR model for FeDOP, where the process follows a pseudo-second order with the interparticle diffusionstep being the rate-limiting step. On the other hand, FeIMP has better fit in the Langmuir model. Photocatalytic activity was observed in FeDOP under UVirradiation by the presenceof reaction-hydroxylated intermediates for MB (m/z = 301)and RhB (m/z = 459). However, the photocatalytic activity was strongly influenced by the adsorption affinity betweendye/catalyst. Photogenerated holes are the species responsible for the dye degradation when the adsorption is too strong, while hydroxyl radical action will be favored when the adsorption is not vigorous as detected by ESI-MS.