LEANDRO GOULART DE ARAUJO
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Artigo IPEN-doc 27250 Synthesis and physicochemical characterization of a novel adsorbent based on yttrium silicate2020 - MEDEIROS, VINICIUS L.; ARAUJO, LEANDRO G. de; RATERO, DAVI R.; PAULA, ALEX S.; MOLINA, EDUARDO F.; JAEGER, CHRISTIAN; MARUMO, JULIO T.; NERY, JOSE G.A new metallosilicate based on yttrium was synthesized and characterized by XRD, FT-IR, 29Si MAS-NMR, and 89Y MAS-NMR. The mixed framework of the material was confirmed by the detection of distinct chemical shift groups using 29Si MAS-NMR (at -82 to -87 ppm, -91 to -94 ppm, -96 to -102 ppm, and -105 to -108 ppm), as well as four distinct chemical shifts in the 89Y MAS-NMR spectrum (at -89, -142, -160, and -220 ppm). Adsorption and kinetic analyses indicated the potential of the new material for the removal of lead and cadmium from aqueous media. The adsorption results for lead indicated that dynamic equilibrium was reached after five hours, with total lead removal of around 94 %, while for cadmium it was reached in the first hour, with total cadmium removal of around 74 %. The adsorptions of lead and cadmium were modeled using pseudo-first order (PFO) and pseudo-second order (PSO) kinetic models. Although both models provided high R2 values (0.9903 and 0.9980, respectively), the PSO model presented a much lower χ2 red value (4.41×10−4), compared to the PFO model (2.12×10−3), which indicated that the rate-limiting step was probably due to the chemisorption of lead from the solution onto the yttrium-based metallosilicate.Artigo IPEN-doc 27144 Physicochemical modifications of radioactive oil sludge by ozone treatment2020 - ARAUJO, LEANDRO G. de; PRADO, EDUARDO S.P.; MIRANDA, FELIPE de S.; VICENTE, ROBERTO; SILVA SOBRINHO, ARGEMIRO S. da; PETRACONI FILHO, GILBERTO; MARUMO, JULIO T.An experimental study on the degradation of organic compounds from radioactive oil sludge by the ozonation process is presented. The effects of different concentrations of ozone in the oil sludge degradation over time were investigated. The experiments were performed in a 0.125 L glass reactor with magnetic stirring and a diffuser plate at the bottom to feed the ozone. The ozone concentration varied from 13 to 53 mg L−1 and the total interaction time was 1 h. To investigate the physicochemical properties of the oil sludge (solid and liquid components) prior to and after the treatment, multiple analytical characterization methods were used: Thermal Gravimetric Analysis, X-ray diffraction, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy, Fourier Transform Infrared spectroscopy, Spectrophotometer, and Residual Gas Analyzer. The most perceptive change is in the color of the liquid medium turned from dark brown to light yellow, especially under ozone concentrations higher than 33 mg L−1. Absorbance values decreased about 3.5 times after 30 min of treatment with [O3] =53 mg L−1. FTIR spectroscopy showed that the bands associated with the CH3 and CeH in CH2 disappeared during treatment. On the other hand, a greater presence of C]C aromatics was observed. By residual gas analysis, various organic and inorganic gases were identified during the treatment, such as CH4, H2, CO2, and H2S. Finally, the ozonation of the oil sludge proved to be effective, due to its high reaction capacity.