Preservação ambiental e reciclagem de óleos residuais

Santos, Vivianni Marques Leite dos; Santos, Luciana da Paz dos; Bidegain, Fabiana Almeida; Santos, Rildo G. Siqueira dos

doi:10.5380/ef.v0i3.24860

Cited by 9 publications

(17 citation statements)

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“…20 This can explain differences for some macro and micronutrients levels found in green (arabica) and roasted coffee samples (probably with the addition of robusta), in addition to factors involved in the industrial process of roasted coffee. 1 The PCA and HCA analysis were applied after autoscaling data due to the different magnitude orders of the concentrations. 21,22 The PCA showed that with only six principal components it is possible to describe 91.4% of data, being 32.3% of the total variance described by the first principal component (PC1), 18.6% by PC2, 14.8% by PC3, 10.7% by PC4, 10.0% by PC5 and 5.0% by PC6.…”

Section: Resultsmentioning

confidence: 99%

“…1 Since the value of coffee beans is based on quality, producers and traders have been motivated to make use of extra tools in order to confirm the geographic origin of the coffee. 2,3 In this context, inorganic chemical analyses of green and roasted coffees may be used to assist the most demanding markets.…”

Section: Introductionmentioning

confidence: 99%

“…2,3 In this context, inorganic chemical analyses of green and roasted coffees may be used to assist the most demanding markets. 1,2,[4][5][6][7][8] Sample preparation still is a critical step in analytical sequence. Among aspects to be taken into consideration in a sample preparation procedure, the most important are the sample size, number and concentration of analytes, type of ashing, compatibility to the measurement equipment, required analytical blanks, time, reagent consumption and suitable precision and accuracy.…”

Section: Introductionmentioning

confidence: 99%

“…There are several articles in the literature that describe the use of different pre-treatment for coffee solubilization involving wet digestion in a focused microwave system, 1 digester heating block, 2,5,6,8 PTFE (polytetrafluorethylene) pressure vessels, 4 PTFE bombs 8 and dry ashing. 6 Most of these procedures present long waiting-time or use high amount of reagents for sample solubilization.…”

Section: Introductionmentioning

confidence: 99%

“…Faster pretreatment procedures have been proposed by using tetramethylammonium hydroxide (TMAH) in digester heating block (10 min; 80 o C; 500 μL of 25% m/v TMAH solution + 0.35 g soluble coffee) 7 or a focused microwave oven (15 min; 6 mL of concentrated HNO 3 + 0.5 mL H 2 O 2 30% m/m + 1 g soluble coffee). 8 Vanadium oxide (V 2 O 5 ) was effective as catalyst for wine decomposition in nitric acid for Cd and Pb determination. 10 However, the use of this catalyst for the acid decomposition of green and roasted coffees in digester heating block for macro and micronutrients determination still requires investigation.…”

Section: Introductionmentioning

confidence: 99%

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Comparative studies of the sample decomposition of green and roasted coffee for determination of nutrients and data exploratory analysis

Filho¹,

Polito²,

Neto³

2007

J. Braz. Chem. Soc.

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Os teores de vários nutrientes foram determinados em 35 amostras de cafés verdes e torrados, por espectrometria de absorção atômica em chama (Ca, Mg, Fe, Cu, Mn e Zn), fotometria de emissão atômica em chama (Na e K) e pelo método Kjeldahl (N) após preparação das amostras por dois procedimentos de decomposição via úmida: i) sistema aberto (bloco digestor) e ii) sistema fechado (forno de microondas convencional com controle de pressão e temperatura). A exatidão dos procedimentos foi verificada analisando-se três materiais de referência certificados do National Institute of Standards and Technology (SRM 1573a Folha de Tomateiro; SRM 1547 Folha de Pessegueiro; SRM 1570a Espinafre). A análise dos dados após a aplicação do teste-t mostrou que os resultados obtidos no procedimento que empregou decomposição assistida por microondas em frascos fechados foram mais exatos do que os obtidos por bloco digestor com frascos abertos no nível de 95% de confiança. Além da exatidão, outras características favoráveis encontradas foram menores valores de branco analíticos, menor consumo de reagentes e menor tempo de decomposição das amostras. Análises exploratórias dos dados empregando-se Análise por Componentes Principais (PCA) e Análise por Agrupamentos Hierárquicos (HCA) mostraram que os elementos Na, K, Ca, Cu, Mg e Fe foram os principais responsáveis na diferenciação das amostras de cafés verde e torrado.The contents of some nutrients in 35 Brazilian green and roasted coffee samples were determined by flame atomic absorption spectrometry (Ca, Mg, Fe, Cu, Mn, and Zn), flame atomic emission photometry (Na and K) and Kjeldahl (N) after preparing the samples by wet digestion procedures using i) a digester heating block and ii) a conventional microwave oven system with pressure and temperature control. The accuracy of the procedures was checked using three standard reference materials (National Institute of Standards and Technology, SRM 1573a Tomato Leaves, SRM 1547 Peach Leaves, SRM 1570a Trace Elements in Spinach). Analysis of data after application of t-test showed that results obtained by microwave-assisted digestion were more accurate than those obtained by block digester at 95% confidence level. Additionally to better accuracy, other favorable characteristics found were lower analytical blanks, lower reagent consumption, and shorter digestion time. Exploratory analysis of results using Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) showed that Na, K, Ca, Cu, Mg, and Fe were the principal elements to discriminate between green and roasted coffee samples. Keywords: sample preparation, coffee, nutrients, exploratory analysis IntroductionCoffee is an important commodity due to the high consumption of its beverage by people worldwide.1 Since the value of coffee beans is based on quality, producers and traders have been motivated to make use of extra tools in order to confirm the geographic origin of the coffee. 2,3 In this context, inorganic chemical analyses of green and roasted coffees may be used to a...

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Comparative studies of the sample decomposition of green and roasted coffee for determination of nutrients and data exploratory analysis

Filho¹,

Polito²,

Neto³

2007

J. Braz. Chem. Soc.

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Membrane-Active Thermoresponsive Block Copolymers Containing a Diacylglycerol-Based Segment: RAFT Synthesis, Doxorubicin Encapsulation, and Evaluation of Cytotoxicity against Breast Cancer Cells

Kurowska,

Markiewicz,

Niemirowicz-Laskowska

et al. 2023

Biomacromolecules

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Herein, we report the formation of drug delivery systems from original thermoresponsive block copolymers containing lipid-based segments. Two acrylate monomers derived from palmitic-or oleic-acid−based diacylglycerols (DAGs) were synthesized and polymerized by the reversible addition−fragmentation chain transfer (RAFT) method. Well-defined DAG-based polymers with targeted molar masses and narrow molar mass distributions were next used as macro-chain transfer agents (macro-CTAs) for the polymerization of N-isopropylacrylamide (NIPAAm) or N-vinylcaprolactam (NVCL). The obtained amphiphilic block copolymers were formed into polymeric nanoparticles (PNPs) with and without encapsulated doxorubicin and characterized. Their biological assessment indicated appropriate cytocompatibility with the representatives of normal cells. Furthermore, compared to the free drug, increased cytotoxicity and apoptosis or necrosis induction in breast cancer cells was documented, including a highly aggressive and invasive triple-negative MDA-MB-231 cell line.

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Evaluation of digestion procedures for simultaneous determination of Ca, P, Mg, K and Na in biodiesel by inductively coupled plasma optical emission spectrometry

Korn¹,

Santos²,

Guida³

et al. 2010

J. Braz. Chem. Soc.

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Neste trabalho foi avaliada a eficiência de dois procedimentos para digestão ácida de amostras de biodiesel visando à determinação de Ca, P, Mg, K e Na por espectrometria de emissão óptica com plasma acoplado indutivamente com configuração axial (ICP OES). Nas digestões em sistema aberto, foi utilizada a mistura contendo ácidos nítrico, sulfúrico e peróxido de hidrogênio e aquecimento condutivo; enquanto que no procedimento empregando forno de microondas com cavidade foi utilizada a mistura contendo ácido nítrico e peróxido de hidrogênio. Os procedimentos foram avaliados considerando-se limites de quantificação, precisão, acidez final dos digeridos e teor de carbono residual. Os teores de carbono residual nos digeridos foram 0,358 ± 0,012% para o sistema aberto com aquecimento convencional e 0,614 ± 0,023% para o sistema fechado com aquecimento assistido por radiação microondas, o que demonstra a alta eficiência dos procedimentos propostos. O sistema de digestão em forno de microondas com cavidade resultou em maior rapidez, segurança e resultados analíticos com percentuais de recuperação de 89,0-103,0% e desvios menores que 5%. Os limites de detecção obtidos, ≤ 0.40 µg g -1 , são adequados para a determinação dos analitos, conforme os limites estabelecidos na legislação brasileira. Três amostras de biodiesel produzidas de diferentes fontes foram analisadas. Em comparação com outros procedimentos propostos na literatura, o procedimento desenvolvido usando forno de microondas com cavidade apresenta vantagens, tais como não necessitar de soluções orgânicas para calibração e não usar solventes orgânicos tóxicos.In the present work, the efficiency of two procedures for the digestion of biodiesel was investigated for the simultaneous determination of Ca, P, Mg, K and Na by axial view ICP OES. In the open system with conventional heating, concentrated nitric and sulfuric acids were added to the samples, and the addition of hydrogen peroxide completed the digestion. In the microwave-assisted closed system, complete digestion was performed using concentrated nitric acid and hydrogen peroxide. The analytical performances were evaluated through limits of quantification, precision of the overall procedures, final acidity of the digests, and residual carbon contents. The contents of residual carbon for the biodiesel samples digested were 0.358 ± 0.012% using the open system with conventional heating and 0.614 ± 0.023% using the microwave-assisted closed vessel system, demonstrating the high efficiency of both proposed procedures. The optimized microwave-assisted decomposition procedure produced the fastest, safest and most accurate analytical results with recoveries of 89.0-103.0% and deviations lower than 5% in most cases. Low limits of detection were obtained (≤ 0.40 µg g -1 ), adequate for the established limits set out in Brazilian legislation for these analytes. Three biodiesel samples produced from different oil sources were analyzed. In comparison with other procedures proposed in the literature, the developed procedu...

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Preservação ambiental e reciclagem de óleos residuais

Cited by 9 publications

References 0 publications

Comparative studies of the sample decomposition of green and roasted coffee for determination of nutrients and data exploratory analysis

Comparative studies of the sample decomposition of green and roasted coffee for determination of nutrients and data exploratory analysis

Membrane-Active Thermoresponsive Block Copolymers Containing a Diacylglycerol-Based Segment: RAFT Synthesis, Doxorubicin Encapsulation, and Evaluation of Cytotoxicity against Breast Cancer Cells

Evaluation of digestion procedures for simultaneous determination of Ca, P, Mg, K and Na in biodiesel by inductively coupled plasma optical emission spectrometry

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