TAMIRES WATANABE
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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.Resumo IPEN-doc 28390 Biossorção de urânio por meio de hidroxiapatita e farinha de osso2021 - WATANABE, TAMIRES; MARUMO, JULIO T.; ARAUJO, LEANDRO G. deArtigo IPEN-doc 27978 Uranium biosorption by hydroxyapatite and bone meal2021 - WATANABE, TAMIRES; GUILHEN, SABINE N.; MARUMO, JULIO T.; ARAUJO, LEANDRO G. deBiosorption has been widely examined for the treatment of aqueous solutions containing uranium, a radiotoxic pollutant. The use of hydroxyapatite and bone meal as potential biosorbents in the removal of uranium (U) from aqueous solutions has not yet been previously addressed. In this work, the efficiency of these biosorbents in the removal of U was investigated according to their adsorption removal capacities. Surface transformations in both materials were observed after U adsorption by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM/EDS). The biomass/U solution ratio was kept at 0.1 g/5 mL. Contact times for the batch experiments were 15, 30, 60, 120, and 180 min, and the concentration of U tested was 680 mg L-1. The equilibrium was achieved in less than 15 min for both materials. The morphological characteristics of each biomass, before and after biosorption experiments were analyzed. Bone meal highlighted slightly superior adsorption results in terms of maximum capacity (qmax = 33.83 mg g-1), compared to hydroxyapatite (qmax = 33.36 mg g-1), with the removal percentages being also similar, 99.97 and 98.57 %, respectively. The results so far indicate that these materials are potential biosorbents for the treatment of uranium-contaminated solutions, especially liquid radioactive waste.Resumo IPEN-doc 27532 Biossorção de urânio por meio de hidroxiapatita e farinha de osso2020 - WATANABE, TAMIRES; MARUMO, JULIO T.; ARAUJO, LEANDRO G. de