LEANDRO GOULART DE ARAUJO
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Artigo IPEN-doc 28879 Biosorption of uranium from aqueous solutions by Azolla sp. and Limnobium laevigatum2022 - ARAUJO, LEANDRO G. de; VIEIRA, LUDMILA C.; CANEVESI, RAFAEL L.S.; SILVA, EDSON A. da; WATANABE, TAMIRES; FERREIRA, RAFAEL V. de P.; MARUMO, JULIO T.The main goal of this study was to assess alternatives to the current challenges on environmental quality and circular economy. The former is here addressed by the treatment of radioactively contaminated solutions, and the latter by using abundant and low-cost biomass. In this paper, we examine the biosorption of hexavalent uranium (U(VI)) in a batch system using the macrophytes Limnobium laevigatum and Azolla sp. by three operational parameters: biomass dose, metal ion concentration, and contact time. Simulated solutions were firstly addressed with two biomasses, followed by studies with real liquid organic radioactive waste (LORW) with Azolla sp. The batch experiments were carried out by mixing 0.20 g biomass in 10 mL of the prepared solution or LORW. The total contact time employed for the determination of the equilibrium times was 240 min, and the initial U(VI) concentration was 0.63 mmol L−1. The equilibrium times were 15 min for L. laevigatum and 30 min for Azolla sp. respectively. A wide range of initial U(VI) concentrations (0.25–36 mmol L−1) was then used to assess the adsorption capacity of each macrophyte. Isotherm models validated the adsorption performance of the biosorption process. Azolla sp. presented a much higher U(VI) uptake (0.474 mmol g−1) compared to L. laevigatum (0.026 mmol g−1). When in contact with LORW, Azolla sp. removed much less uranium, indicating an adsorption capacity of 0.010 mmol g−1. In conclusion, both biomasses, especially Azolla sp., can be used in the treatment of uranium-contaminated solutions.Artigo IPEN-doc 28285 Synthesis of geopolymers for immobilization of radioactive waste using sewage treatment plant sludge2021 - CASAS, A.; ARAUJO, L.; GARCIA, R.; VICENTE, R.; FRANCO, M.; MARUMO, J.Artigo IPEN-doc 26681 Radiochemical characterization of spent filter cartridges from the primary circuit of a research reactor2019 - GERALDO, BIANCA; ARAUJO, LEANDRO G. de; TADDEI, MARIA H.T.; FERREIRA, MARCELO T.; MADUAR, MARCELO F.; VICENTE, ROBERTO; MARUMO, JULIO T.Radiochemical-based analyses have been used for the characterization of radioactive waste. Nevertheless, the determination of alpha, beta and gamma emitters by radiochemical analysis of spent cartridge filters from a swimming-pool type reactor has not been previously addressed. This work aims at identifying and quantifying the radionuclides present in this waste, including the difficult to measure radionuclides. The distribution of the radionuclides in the filter was investigated by the determination of gamma-emitting nuclides and the z-score of the measured activity concentrations. The results indicated that all the filters are homogeneous, meeting the homogeneity criteria recommended by the International Atomic Energy Agency.Artigo IPEN-doc 19353 Chemical analysis of radioactive mixed liquid wastes by alpha/gamma spectrometry, ICP-OES and arsenazo III2013 - FERREIRA, EDUARDO G.A.; FERREIRA, RAFAEL V.P.; ARAUJO, LEANDRO G.; TADDEI, MARIA H.T.; DELLAMANO, JOSE C.; MARUMO, JULIO T.