MARIANA NOVAIS DE ANDRADE

MARIANA NOVAIS DE ANDRADE

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Optimizations on Lithium ion exchange separation and isotopic measurements
2022 - OTOMO, JULIANA I.; GIMENEZ, MAISE P.; ANDRADE, MARIANA N. de; MONTEIRO, LUCILENA R.; NASCIMENTO, LETICIA da S.; BATAGLIA, HENRIQUE; LEAO, PAULO H.B.; CECILIO, PRISCILA de S.; BERGAMASCHI, VANDERLEI; COUTINHO, JOAO F.; BUSTILLOS, JOSE O.W.V.
Introduction: The Lithium-7 is of interest for nuclear application, being used for primary cooling of PWR (Pressurized Water Reactor) reactors [1]. An environmentally friendly technique is required to replace the Mercury amalgam technique used worldwide [1,2]. This work aims to present the preliminary results of the development of 7Li separation by ion exchange. Methods: A 120 mm x1.0 cm i.d. glass column filled with Dowex 50W-x16 resin was used. A total of 3.0 liters of 0.2 M CH3COOLi solution percolated the column in order to saturate and displace the formed band of 6Li and 7Li. Fractions were collected every 50 mL, then the resin was washed with 5M HNO3 and ultrapure water. The fractions were filtered and evaporated at 80°C, finally taken up with HNO3 1%. Samples were analyzed by ICP-OES – SPECTRO ARCOS. The fractions were analyzed by ICP-MS, model ELAN 6000 – SCIEX. For isotopic ratio measurement, with the parameters of gas flow of approximately 1.1 L min-1, RF 600 W, gas flow rate 1.2 L min-1, Peak Hopping mode, dwell time 80 and 480 for 6Li and 7Li (respectively), 50 sweeps per reading, 1 read per replicate and 10 replicates. Results: A total of 63 samples were collected from the separation experiment. The Li isotopic ratio measured for each fraction was assessed by ANOVA one-way considering the differences among fractions. A statistical significant difference was observed between the fraction 1 and the remainder fractions and the load solution. The remaining fractions showed an isotopic ratio around the natural abundance (6Li/7Li: 7.59%/92.41% = 0.082). The isotopic ratio of this sample indicated enrichment of 7Li of 0.92% in the fraction number 30. Conclusions: The method of ion exchange with Dowex 50W-x16 resin was efficient on 7Li separation and through ICP-MS method was able to measure the δ 84%₀ enrichment of the 7Li. The isotopic separation procedure via ion exchange is still being studied, however the results are promising.
Sodium interference in lithium isotope ratio analysis by Inductively Coupled Plasma Mass Spectrometry
2022 - ANDRADE, MARIANA N. de; OTOMO, JULIANA I.; GIMENEZ, MAISE P.; NASCIMENTO, LETICIA da S.; NASCIMENTO, HENRIQUE B. do; LEAO, PAULO H.B.; CECILIO, PRISCILA de S.; FERREIRA, JOAO C.; BERGAMASCHI, VANDERLEI S.; BUSTILLOS, OSCAR V.
Introduction: Naturally occurring lithium consists of two stable isotopes, 6Li (7.591%) and 7Li (92.409%) and have applications in nuclear technology, pharmaceutical, automotive and geological research. Enriched 7Li isotope in LiOH form has been used as a pH regulator for Pressurized Water Reactor (PWR) reducing corrosion in the primary water circuit [1-3]. The determination of lithium isotopic composition was analyzed by Inductively Coupled Plasma Mass Spectrometry after ion exchange processes, which has been considered a promising technique for the separation of Li isotopes. One of the concerns in ICP-MS analysis is sodium interference. The presence of sodium in the lithium-containing sample has potential implications for the accuracy of isotopic ratio measurements. For this reason, a method is described for the study of sodium interference in 7Li 295,88%₀ and 303,30%₀ enriched solutions. Methods: For this study, the reference standard L-SVEC was used, it has an isotopic abundance of 92.409% for 7Li and 7.591% for 6Li (6Li/7Li ratio = 0.08251) and solutions enriched at 295,88%₀ (6Li/7Li ratio = 0.06661) and 303,30%₀ (6Li/7Li ratio = 0.06810) of 7Li. Concentrations of 50 μg L-1 of lithium were maintained for the solutions used and it was evaluated with the addition of 50, 100, 300, 450 and 1000 μg L-1 of sodium on the enriched samples suffered significant changes in their isotopic ratio. The ICP-MS used for the sample analysis was a PerkinElmer SCIEX Elan 6000. For the isotopic ratio measurement the parameters used was nebulizer gas flow of approximately 0.94 L min-1 , Radio Frequency (RF) 600 W, gas flow rate 1.2 L min-1 , Peak Hopping mode, dwell time 80 and 480 ms for 6Li and 7Li respectively, 50 sweeps per reading, 1 read per replicate and 10 replicates. Results: For this study, 24 samples were analyzed being divided into four sets of samples with 6 samples each set. The sets were composed of samples without addition of sodium and samples with addition of 50, 100, 300, 450 and 1000 μg L-1 of sodium. The first set of samples, composed of the 295,88%₀ enriched sample, had a standard deviation of 3.59✕10-4. The second set of samples, composed of the 303,30%₀ enriched sample, had a standard deviation of 2.63✕10-4. The third and fourth set of samples, composed of aliquots of the L-SVEC standard, obtained a standard deviation of 2.22✕10-4 e 2.54✕10-4, respectively. Showing that the addition of sodium did not significantly interfere in the ratio of lithium isotopes 6 and 7 according to standard deviation. Conclusions: Through the results obtained from the experiment, it was observed that the variation in the ratio between isotopes 6 and 7 of lithium was not significant for the results of analysis in ICP-MS. However, it should be noted that for the purposes of lithium isotope separation processes using ion exchange resins, the interference of sodium in the chromatographic separation needs to be evaluated.
Comparison of 238U mass fraction measured by ICP–MS and Instrumental Neutron Activation Analysis techniques
2022 - TAPPIZ, BRUNO; SILVA, PAULO S.C. da; OSTERMANN, CAROLINE; LIMA, NICOLE P. de; ANDRADE, MARIANA N. de; BUSTILLOS, OSCAR V.
Introduction: Uranium is an element present in ambient air, water, soil and rocks [1]. The most abundant natural radioisotope of this actinide (238U) produces in its chain decay the radionuclide 222Rn [2], which is a tracer for atmospheric mixing and transport model validations [3]. The 238U activity concentration in superficial soil samples is a crucial parameter for some 222Rn flux map modeling methodologies [4]. Methods: In this study, 18 superficial soil samples were analyzed. The content of 238U was assessed using two techniques: (i) by the comparative method of the Instrumental Neutron Activation Analysis (INAA) [5] and by ICP–MS (ELAN 6000, PerkinElmer) [6]. Certified Reference Materials (CRM) SRM 1646a Estuarine Sediment and USG STM–2 were used both as comparators in the INAA technique and to ensure quality control. The normality and homoscedasticity of the data were evaluated. Finally, the Mann- Whitney U test [7] was used to assess whether or not there is a significant difference (α = 0.05) between the two techniques. Results: The z-score was calculated to ensure quality control. Z-scores values was obtained by the Modified Horwitz Equation [8], which takes into account the order of magnitude of the content of the analyte and is independent of the CRM uncertainties, unavailable for the CRM used. The z-score values obtained (n = 3) for the radionuclide 238U were 0.5 for the CRM USG STM–2 and -0.4 for SRM 1646a. The z-scores obtained are smaller than 2 therefore they are considered satisfactory [9]. Regarding the statistical parameters of the comparison between the techniques, the normality (Shapiro Wilk) was not verified (p = 0.02 for ICP-MS and p = 0.03 for INAA). The p-value for the test for equal variances (F test) was 0.71 Mann-Whitney U test was used instead of Student’s test due to the non-verification of the normality parameter in the data. The p-value from the Mann-Whitney test (0.51) indicates that there is no significant difference between the 238U content measured by the two techniques. Conclusions: Statistical analysis showed that there is no significant difference between the 238U mass fraction measured by the ICP–MS and the INAA – comparative method. In the future, certified reference materials will also be assessed by ICP–MS in order to corroborate this statistical comparison from a metrological point of view.
Use of the ion exchange technique for purification of lithium carbonate for nuclear industry
2021 - ANDRADE, MARIANA N.; OLIVEIRA, GLAUCIA C.; CONTRIM, MARYCEL E.B.; SENEDA, JOSE A.; BUSTILLOS, OSCAR V.
Exploring chiral BVOCs in Amazon and Atlantic forest by TENAX® and Carbograph® sorbent
2019 - OSTERMANN, CAROLINE; ZANNONI, NORA; CARVALHO, ELIAS; NOVAES, MARIANA; WILLIAMS, JONATHAN; VEGA, OSCAR
Caracterização química dos compostos orgânicos voláteis biogênicos via GC/MS
2019 - ANDRADE, MARIANA N. de; BUSTILLOS, JOSE O.V.
Purification of lithium carbonate by ion-exchange processes for application in nuclear reactors
2019 - ANDRADE, MARIANA N.; OLIVEIRA, GLAUCIA A.C.; PIRANI, DEBORA A.; COUTINHO, JOAO F.; BERGAMASCHI, VANDERLEI S.; SENEDA, JOSE A.; BUSTILLOS, JOSE O.V.
Lithium Compounds have applications in strategic areas for intern consumption of a country as well as international commerce. In nuclear industry, the lithium is used for the cooling of PWR reactors as a pH stabilizer. Based on this assumption, the generation of knowledge to master the processing cycle of these compounds is essential. The high degree of purity of lithium compounds is determinant to have success in these applications. Lithium hydroxide LiOH and lithium carbonate Li2CO3 are the main forms in which lithium is used industrially. To improve the quality of the starting product, purifying process were used until obtaining an adequate purity level of raw material (> 99%). The present work aims to make feasible a purification of Li2CO3 through ion-exchange chromatography from a 98.5% purity compound. The impurities present in higher content are sodium and calcium. To separate these two elements from lithium or at least to lower their concentrations, a column with cationic resin was used to fix lithium. The determination of lithium, sodium and calcium contents in the solutions was performed by inductively coupled plasma optical emission spectrometry, ICP-OES. The experiments performed to evaluate the best lithium purification condition were based on the variation of the main operational parameters: pH, flow and elution solution. The results indicate increased purity from the application of ion exchange operations obtaining a suitable condition for nuclear uses.
Purificação do carbonato de lítio via troca iônica
2018 - OLIVEIRA, G.C.; FERREIRA, J.C.; BERGAMASCHI, V.S.; SENEDA, J.A.; COTRIM, M.B.; FURUSAWA, H.A.; BUSTILLOS, O.V.; PIRANI, D.A.; ANDRADE, M.N.
A obtenção de compostos de lítio, especificamente o hidróxido de lítio, LiOH, e o carbonato de lítio, Li2CO3, é resultado de processos de extração a partir de diversos minerais, entre estes o ? – espodumênio, LiAlSi2O6. Produtos com grau de pureza da ordem de 85% em Li2CO3 são utilizados para aplicações em esmaltes sintéticos, adesivos, graxas e lubrificantes. Já para aplicação em baterias de automóveis e medicamentos é necessário um grau de pureza da ordem de 99% em Li2CO3. O objetivo deste trabalho é viabilizar a purificação do Li2CO3 via operação de troca iônica. As impurezas presentes em maior teor no Li2CO3 são o sódio e o cálcio. Para separar esses dois elementos do lítio ou pelo menos, diminuir as suas concentrações, foi utilizada uma coluna com 100 mL de uma mistura de 90% da resina catiônica fraca do tipo carboxílico e 10% da resina aniônica forte, para fixar o lítio. Essa mistura foi condicionada a pH 8,5 a partir da lavagem com solução de hidróxido de amônio, NH4OH. Foi utilizada uma solução de Li2CO3, 98,5% de pureza nos experimentos. O lítio retido pela mistura de resinas foi eluido com solução de ácido clorídrico, HCl, 0,5 mol L-1. A determinação dos teores de lítio, sódio e cálcio nas soluções, foi realizada por Espectrometria de Emissão Óptica com Fonte de Plasma de Argônio, ICP-OES, em cada ciclo cromatográfico da troca iônica, tais como sorção, lavagem e desorção. Os experimentos realizados para avaliar a melhor condição de purificação do lítio basearam-se na variação dos principais parâmetros operacionais (pH e vazão). Para uma vazão de 2 mL min-1 os resultados parciais mostraram que cerca de 70% de lítio foram retidos na mistura de resinas e o restante passou com o efluente. Os cálculos correspondentes sugerem que, a partir das soluções obtidas na etapa de eluição, obtém-se o Li2CO3 com pureza da ordem de 99% após uma única etapa de percolação. A sequência deste trabalho será a verificação da eficiência de purificação baseada em um sistema de colunas em tandem. Além disso, após o estabelecimento das condições experimentais básicas, o processo será otimizado utilizando-se a abordagem do planejamento fracionário saturado.