LEANDRO GOULART DE ARAUJO

LEANDRO GOULART DE ARAUJO

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Synthesis of geopolymers for immobilization of radioactive waste using sewage treatment plant sludge
2021 - CASAS, A.; ARAUJO, L.; GARCIA, R.; VICENTE, R.; FRANCO, M.; MARUMO, J.
Uranium biosorption by hydroxyapatite and bone meal
2021 - WATANABE, TAMIRES; GUILHEN, SABINE N.; MARUMO, JULIO T.; ARAUJO, LEANDRO G. de
Biosorption 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.
Oxidative degradation of organic compounds from sludge by ozonation
2019 - ARAUJO, LEANDRO G. de; WATANABE, NAOMI; SILVA, THALITA T.; TEIXEIRA, ANTONIO C.S.C.; VELOSA, ADRIANA C. de; MARUMO, JULIO T.
This study investigates the performance of the ozonation process in the treatment of petroleum sludge from an offshore production platform situated in Brazil. The effect of operating conditions is studied such as the phase to be treated and the sludge/water ratio. Total organic carbon content increased in O2 and O3 experiments, mainly because of the mixing factor. The decrease of sludge mass was observed in a situation of forced mixing and with only ozone flow. The liquid phase indicated a high TOC value, but very low radioactive activities, whereas the solid phase did not present detectable TOC amounts but significant values of radioactive activity. More experiments and analyzes will be carried out to obtain more relevant results for future discussion.
Oil sludge treatment by electron beam irradiation
2019 - TESSARO, ANA P.G.; CASAS, ALEXANDRE L.; TEIXEIRA, ANTONIO C.S.C.; VICENTE, ROBERTO; MARUMO, JULIO T.; ARAUJO, LEANDRO G. de
Radiation induced advanced oxidation processes have been proposed for the treatment of various types of wastes. However, electron beam technologies for the removal of recalcitrant compounds in petroleum wastes are still poorly understood. This work aims at evaluating the effects on the degradation of organic matter from oil sludge by electron beam irradiation. The radiometric analysis was also performed to identify radionuclides and measure dose rates. An electron beam accelerator, model Dynamitron II, with variable current up to 25 mA was employed and the irradiation dose values ranged from 20 to 250 kGy. Solutions were prepared with an initial H2O2 concentration of 1.34 mol L 1. Samples without H2O2 addition, but with water were also evaluated. Control tests with dry and pulverized sludge were submitted to irradiation. The effects on the removal of total organic carbon and the sludge degradation are discussed.
Chemical analysis of radioactive mixed liquid wastes by alpha/gamma spectrometry, ICP-OES and arsenazo III
2013 - FERREIRA, EDUARDO G.A.; FERREIRA, RAFAEL V.P.; ARAUJO, LEANDRO G.; TADDEI, MARIA H.T.; DELLAMANO, JOSE C.; MARUMO, JULIO T.
Evaluation of the resin oxidation process using Fento's reagent
2013 - ARAUJO, LEANDRO G.; GOES, MARCOS M.; MARUMO, JULIO T.
Degradation of ion exchange resin using Fenton's reagent
2011 - ARAUJO, LEANDRO G.; SAKATA, SOLANGE K.; MARUMO, JULIO T.