DISSERTAÇÃO DE MESTRADO - PROGRAMA DE PÓS-GRADUAÇÃO EM QUIMICA

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ESTUDO DAS REAÇÕES DE OXIDAÇÃO DE METANOL E ETANOL SOBRE CATALISADORES BI E TRIMETÁLICOS ATRAVÉS DE TÉCNICAS DE VOLTAMETRIA CÍCLICA E DEMS
(Universidade Federal do Maranhão, 2006-07-24) Silva, Quésia Guedes da; RODRIGUES, Isaide de Araújo; CPF:17928893304
The interest in the use of methanol and ethanol as fuels in a fuel cell is justified by the search for new energy conversers, more efficient and less polluters. This work presents the study of the oxidation reaction these alcohols on catalysts obtained by potentiostatic deposition of Pt or codeposition of PtRu, PtRuSn e PtSn using as subtract a Teflon membrane GORE-TEK with sputtering of 600nm of gold and a geometric area of 1,11cm2. The reference electrode used was the reversible of hydrogen, as an opposite electrode there was a platinum sheet. The experiments were made using the combination of cyclic voltammetry and on line mass spectrometry, called differential electrochemical mass spectrometry (DEMS) The electroposits were examined using X-ray energy dispersive analysis (EDAX) and scanning electron microscopy (SEM) The electrochemistry results have shown that Pt-Ru catalyst presented better catalitic activity to methanol oxidation in lower potentials, showing the following sequence to catalitic activity: PtRu > PtRuSn @ PtSn > Pt. The mass spectrometry data have shown similar results with better performance to PtRu electrode in the CO2 (m/z = 44) production. In the case of the ethanol oxidation the electrochemistry data show that the catalyst Pt-Sn and Pt-Ru- Sn were the most active in lower potentials. The mass spectrometry results have shown that, when compared with others, the PtSn electrode presents greater activity both in the CO2 production as well as in the acetaldehyde s.
OTIMIZAÇÃO DO PROCESSO DE PRODUÇÃO DE BIODIESEL METÍLICO E ETÍLICO DO ÓLEO DE MAMONA (Ricinus Communis L.) APLICANDO UM DELINEAMENTO COMPOSTO CENTRAL ROTACIONAL (DCCR)
(Universidade Federal do Maranhão, 2007-08-29) Brandão, Kiany Sirley Ribeiro; Maciel, Adeilton Pereira; CPF:92935427491; SILVA, Fernando Carvalho; CPF:14807513320; http://lattes.cnpq.br/3470815419519342; Mouchrek Filho, Victor Elias; CPF:70434212415; http://lattes.cnpq.br/2381183158978639
The biodiesel is a biofuel obtained from renewable sources, as vegetable oils and animal fats. The castor seeds (Ricinus communis L.) have a medium content of oil of 47%. This oil when transformed in biodiesel produces a fuel with a series of environmental advantages in relation to petroleum diesel. Therefore in this work it was made the optimization of the production process of the methyl and ethyl biodiesel from castor oil, varying the reaction time, the catalyst amount and the oil:alcohol ratio (methanol or ethanol) using a Central Rotatable Composite Design (CRCD) symmetrical and of second order, constituted of two parts: the factorial 2n, with central points, and the axial part. With base in this factorial planning, surfaces and curves of responses and variance analysis, it was evaluated the effects and the significance of the models for the responses variables, biodiesel yield in mass and the esters content. For the production of methyl biodiesel, the greater biodiesel yield in mass is reached when oil/methanol molar ratio 1:4-1:5; 0,4-1,2% of KOH and time reaction 20-100 min, is used. In function of the esters content, the oil/methanol molar ratio should be between 1:10 and 1:11,36, KOH concentration between 1,4 and 2,34 and reaction time between 120 and 140 min. The regression models of the methyl biodiesel for ANOVA appropriately explained at the level of 95%, the data variation (R2 = 0,90567, for yield biodiesel and R2 = 0,7654, for the esters content). For the production of the ethyl biodiesel, the results of the factorial planning 23 showed that the oil/ethanol ratio and the KOH concentration went statisticaly significant to the biodiesel yield in mass and content of esters. The maximum yield can be reached when oil/ethanol molar ratio between 1:10,4 and 1:12,35; 1,4 to 2% of KOH and 60- 100 min of reaction, is used. In function of the esters content, the oil/ethanol molar ratio should be between 1:10,5 and 1:12,35, concentration of KOH between 1,4 and 2,0 % and time of reaction between 60 and 120 min. The regression models explained the variation of the data appropriately (R2 = 0,71811, for biodiesel yield and for esters content, R2 = 0,95217) and they acted significantly, to 95% of trust limit, the relationship between the independent variables and the response. The samples of the methyl and ethyl biodiesel of castor oil, in the optimized conditions, they are inside of the limits preset by National Agency of the Petroleum, Natural Gas and Biofuels.
CASCA DE ARROZ COMO ADSORVENTE PARA ÍONS DE METAIS PESADOS: Caracterização e modificação química
(Universidade Federal do Maranhão, 2009-01-09) Penha, Rosiane Silva; BEZERRA, Cícero Wellington Brito; CPF:31155910397; http://lattes.cnpq.br/1474300723265204; Ramos, Antonio Carlos da Silva; CPF:70434212415
Adsorption of some metal ions (Co2+, Ni2+, Cu2+ e Zn2+) from aqueous solutions (pH 5.0) onto in nature rice husk (0.088 <  < 0.177 mm) was investigated. All experiments were conducted by the batch adsorption techniques at room temperature (28  1°C) and under constant stirring. The adsorption amounts were determined using atomic absorption spectroscopy. The Adsorption data were studied using two well-known adsorption models: Langmuir and Freundlich. The results showed that the metal ions uptake processes mediated by rice husks were fitted Freundlich isotherm model, suggesting that all adsorptions are governed by weak electrostatic interactions. According to the equilibrium studies, the selectivity sequence can be given as: Ni2+ (0.08 mmol g-1) < Co2+ (0.16 mmol g-1) < Zn2+ (0.40 mmol g-1) < Cu2+ (0.89 mmol g-1). This result showed that natural rice rusk holds good potential to remove such metal ions from wastewater. The effect of chemical pretreatment of rice husk on adsorption was also investigated. In nature rice husk (IN) was pretreated with phosphoric acid (AF); phosphoric acid and urea (AFU) and sodium metaperiodate (MP). AFU was the best adsorbent for all metal ions investigated [Ni2+ (0,96 mmol g-1) < Cu2+ (1,20 mmol g-1) < Co2+ (1,59 mmol g-1) < Zn2+(1,80 mmol g-1)]. In addition, in nature rice husk was characterized by chemical-bromatological analyses (humidity, ash, protein, carbohydrate, starch, lipid and fibers), scanning electron microscopy, solid-state 13C NMR and specific BET surface area. Some properties of in nature and pretreated samples were studied by infrared spectroscopy, thermogravimetric analysis, X-ray diffractometry, and elemental analyses. The results showed only marginal changes among them.
ESTABELECIMENTO DE CONDIÇÕES ANALÍTICAS PARA DETERMINAÇÃO DE HORMÔNIOS ESTRÓGENOS EM ÁGUA POTÁVEL DISTRIBUÍDA NA CIDADE DE SÃO LUÍS-MA
(Universidade Federal do Maranhão, 2009-04-28) Verbinnen, Raphael Teixeira; NUNES, Gilvanda Silva; CPF:27928853353; http://lattes.cnpq.br/5833210771020427
Given the humanity perception of necessity to preserve the environment and the incessant search for sustainable development, today the preservation of natural water sources is by far one of the most worrying factors for the preservation of life. Besides the most common aquatics pollutants, also there is one called emerging pollutants, which in recent decades have been detected due the technological advances. These involve mainly the organic micropollutants, which present the endocrine disrupters (ED's) main group. Among the ED's, the natural and synthetic sex steroids hormones have significant importance because their daily use in medicine, in the replacement therapy and contraceptive methods, which has contributed to the continuous release in domestic sewage. There are several consequences of this effect, including fertility declining, occurrence of various cancers and disorders in the development and homeostasis of organisms. The domestic and industrial sewage and leaching from agricultural fields fertilized with sludge from sewage treatment plants (STP's) are the main sources of contamination. This study allowed the chromatographic separation of the hormones estriol (E3), 17 β-estradiol (E2), estrone (E1) and 17 α-ethynylestradiol (EE2) in relatively short duration (16,5 minutes), using the acetonitrile:water (ACN: H2O) mixture as mobile phase in gradient mode, constant flow of 1 mL min-1, injection volume of 20 μL, λ = 280 nm and temperature of 27 ºC. The method was developed in two laboratories, involving different instruments. Four procedures and two adsorbents (C18 e OPT) of SPE were tested. The sample preparation method, including dechlorination and the SPE procedure with C18 cartridge, resulted in the recovery values within the acceptable limit. The developed method was validated according to guidelines of the ANVISA`s Guide for Validation, and bioanalytical methods was adapted for this study. The method was then applied in the analysis of the natural (17β-estradiol, estrone and estriol) and the synthetic (17α-ethinylestradiol) hormone in drinking water from the city of São Luís Peaks were not identified for the substances studied, probably substances concentrations below the limits of detection and quantification of the method were found.
SÍNTESE E CARACTERIZAÇÃO DE ÉTERES DE GLICERINA COMO ADITIVOS OXIGENADOS PARA O DIESEL
(Universidade Federal do Maranhão, 2010-05-31) Mendonça, Sergiane de Jesus Rocha; Silva, Fernando Carvalho; CPF:14807513320; http://lattes.cnpq.br/3470815419519342; MACIEL, Adeilton Pereira; CPF:92935427491
Currently, the growth of world production of biodiesel is generating a large surplus of glycerin, devaluing it in the market, being necessary to transform it into products of higher added value. One way of valuing the glycerin is its etherification to be used as oxygenate additives in diesel. In this work we studied the production of glycerin ethers using alcohols cyclohexanol, isoamyl, benzyl, tert-butyl, methyl and isopropyl alcohol as eterificantes in the presence of acid catalysts, acid p-toluene sulfonic acid, the ion exchange resin Amberlyst 15 and niobia and alumina catalysts modified. The reactions were performed in high-pressure reactor and flask with a reflux system. The qualitative and quantitative analysis of the obtained products were performed using the technique of Thin Layer Chromatography, Gas Chromatography with Mass Spectrometry and Infrared Spectroscopy. The reactions which have the highest incomes were those processed in the presence of Amberlyst 15 with benzyl alcohols and tert-butyl-ether yielding 60.46% and 65.68% of mono-etherified glycerin, respectively, and with the tertiary butyl alcohol butyl alcohol in the presence of alumina catalyst modified with cerium obtaining 59.45% of glycerin ethers. Samples of pure diesel were doped with the reaction products of benzyl alcohol and tert-butyl ether at a ratio of 0.5 and 5.0%, v / v, which do not significantly influence the properties of diesel.
OBTENÇÃO DE CATALISADORES HETEROGÊNEOS PARA REAÇÃO DE TRANSESTERIFICAÇÃO
(Universidade Federal do Maranhão, 2010-09-17) Tavares, Mauro Henrique Almeida; MACIEL, Adeilton Pereira; CPF:92935427491
The biodiesel is produced mainly via homogeneous catalysis, however this process presents some disadvantages such as saponification of esters and the difficulty of separating the catalyst of the formed products. In this work ceramic catalysts were prepared from the application of the surface coating, nanometrics, BaO, CaO and MgO in commercial alumina, in order to improve the catalytic activity in the transesterification reaction, mainly triglycerides. The catalysts were obtained from the surface modification of alumina using a combined technique between sol-gel and polymeric precursors. The obtained catalysts were characterized by Infrared Spectroscopy techniques with Fourier Transform, Scanning Electron Microscopy, Electronic, Optical Microscopy, X-rays Diffraction and Analysis of gas adsorption. The coating in nanometric was observed in only a few particles of support. It was observed that the characteristics of support are essential to obtaining the catalysts for the reaction transesterification of babassu oil, as regards the conversion and processing. The catalysts of alumina with BaO, CaO and MgO showed catalytic for the production of biodiesel. However, with 5 % catalyst in reaction to oil, all catalysts have income above 90 %. Thus, the catalysts were effective for the transesterification of babassu oil for the production of biodiesel.
Redução do Oxigênio Molecular por [Fe(Bipy)3]/C: influência do suporte e do tratamento térmico na atividade catalítica.
(Universidade Federal do Maranhão, 2011-01-25) Rêgo, Ulisses Alves do; BEZERRA, Cícero Wellington Brito; 311.559.103-97
This work consisted in the preparation and study of catalytic activity for reduction of molecular oxygen (ROM) based on head-treated coordination compounds with nitrogenated ligands, impregnated on carbon nanosupports (nanotube - NTC, and nanoparticles - Vulcan). The following ions complexes [Fe(bipy)3]2+ and [Fe(TPTZ)2]2+ (2,2 '-bipyridine and 2 ,4,6-tris (2-pyridyl) -1,3,5-triazine) were synthesized and characterized in solution (electron spectroscopy in the region UV-vis, cyclic voltammetry). The following materials were prepared C1: Fe(10%)-Bipy/NTC; C2: Fe(5%) -Bipy/NTC; C3: Fe(5%)-Bipy/Vulcan and C4: Fe(5%)-TPTZ/Vulcan. The comparison between C1 and C2, and between C2 and C3 materials, showed, respectively, the effect of metal loading and the nature of the carbon support on their catalytic efficiency. The comparison among all and C4 (already reported in the literature) allowed the verification of experimental methodology employed. The effect of temperature on the electrocatalytic performance was observed for C1. The following pyrolysis temperatures were used: 600-1000 oC. The results showed that metal loading and the nature of the support influence the catalytic ability of the materials. The best pyrolysis temperature observed to generate active sites in C1 for the ROM was at 800 oC. All materials were treated at this temperature, and the efficiency order observed was: C4 (Fe (5%) -TPTZ/Vulcan) >> C1 (Fe(10%)-Bipy/NTC) > C2 (Fe(5%)-Bipy/NTC) > C3 (Fe (5%) -Bipy/Vulcan). For not heat treated materials, the activity order observed was: C3 (Fe(5%)-Bipy/Vulcan) C4 (Fe (5%)-TPTZ/Vulcan) > C1 (Fe (10%)-bipy/NTC) > C2 (Fe (5%) -Bipy/NTC). C2 and C3 catalysts showed a tendency to reduce the molecular oxygen according to 2e- mechanism, while C1 and C4 materials by 4e- mechanism. For some reason, the TPTZ ligand favored the generation of catalytic sites more efficient than Bipy in these materials.
ESTUDO QUÍMICO E ATIVIDADE ANTIFÚNGICA DO ÓLEO ESSENCIAL DOS FRUTOS DA Pimenta dioica Lindl.
(Universidade Federal do Maranhão, 2011-06-10) B. Júnior, Francisco Reivilandio da S.; MOUCHREK FILHO, Victor Elias; CPF:70434212415; http://lattes.cnpq.br/2381183158978639
Jamaican pepper, Pimenta dioica Lindl, is a species belonging to the family of Myrtacea, measuring 6m to 15m high, very aromatic in all its parts. It is originally from Central America and West India and with great economic importance in the market of essential oils. The extraction of the essential oil of Pimenta dioica L seeds was carried out by using the method of hydrodistillation known as Cleverger system. It was extracted from a maximum volume of oil in the period of four hours with a yield of 2.8% m/m. The UV spectrophotometric techniques, mass spectrometry and gas chromatography, as well as the physical constants, density, color and appearance were used to identify the compound eugenol and other constituents of the essential oil of P. dioica L. Through the technique of external standard and standard addition it was quantified with a eugenol percentage of 76.98%, forming the major component. The essential oil of Pimenta dioica L was applied to the phyto pathogenic fungi species Fusarium oxysporum f. sp. lycopersici, Fusarium oxysporum f. sp. passiflorae, Fusarium subglutinans f. sp ananas., Fusarium oxysporum f. sp. vasinfectum and Fusarium oxysporum f. sp. cubense resulting in a total inhibition of mycelial growth of all species tested for a period of ten days of evaluation.
ESTUDOS DE CATALISADORES TERNÁRIOS À BASE DE PLATINA, ESTANHO E MOLIBDÊNIO SUPORTADOS EM CARBONO PARA AS REAÇÕES DE OXIDAÇÃO DE METANOL E DE ETANOL
(Universidade Federal do Maranhão, 2012-04-18) Santos Junior, Antonio Fernandes dos; TAKANA, Auro Atsushi; CPF:00548204802; Rolemberg, Marlus Pinheiro; CPF:72192119453; http://lattes.cnpq.br/1520599055684991
The electrocatalytic activities of trimetallic catalysts based on platinum, tin and molibdenum, dispersed on Vulcan XC-72 carbon using an alcohol reduction method, were investigated for methanol and etanol oxidation reactions in acid solutions, with cyclic voltammetry, steady-state polarization curves and chronoamperometry. Among the catalysts Pt8Sn1Mo1/C, Pt7Sn1,5Mo1,5/C e Pt6Sn2Mo2/C investigated, the best performance was recorded on Pt6Sn2Mo2/C for the electrooxidation of metanol, as well as ethanol. In addition, such results when compared with those obtained on Pt/C sintesized by the same procedure, as well as on Pt/C-ETEK commercial sample, showed the higher electrocatalytic activity of the Pt6Sn2Mo2/C catalyst.
SÍNTESE E CARACTERIZAÇÃO DE CATALISADORES HETEROGÊNEOS TIPO PEROVSKITA PARA CONVERSÃO DE ÓXIDO DE NITROGÊNIO E MONÓXIDO DE CARBONO EM GASES DE COMBUSTÃO DE DIESEL
(Universidade Federal do Maranhão, 2012-04-23) Bezerra, Débora Morais; MACIEL, Adeilton Pereira; CPF:92935427491
This study aims to prepare, characterize and study materials type perovskite (Ba3BB‟2O9 and Ba2BB‟O6) as catalysts for the reaction of NOX and CO conversion, seeking other alternatives for catalytic converters. The compounds were prepared using a polymeric precursor method, calcined at 500, 700 and 900 ° C in the period of two hours. Characterized by X-ray diffraction, infrared by transformed of Fourier, Raman and Microscopy electronic of scanning spectroscopy. According to DRX, the method favors the formation of perovskite phases treated at 400 °, 500 °, 700 ° and 900 ° C, obtaining the desired compounds in the presence of the secondary phase. In the analysis of infrared spectroscopy, verified the presence of a characteristic vibrational, that to correspond the connection between the metal-oxygen, which becomes more intense when occurs the increase in the heat treatment. This behavior has been confirmed by the stretching associated with internal vibration of the oxygen of the octahedron in 360 cm-1 and 410 cm-1 of the A1g(O) e 2Eg(O) observed in the sample belonging to the order of 1:2. For catalytic activity toward conversion reaction of the gases mentioned, were more active for CO, highlighting the perovskite Ba3CaNb2O9 where the conversion was directly proportional to the formation of the structure of the compound and the reduction of the presence of secondary phase.
ÓLEO ESSENCIAL DOS BOTÕES FLORAIS DO CRAVO-DA-ÍNDIA (Syzygium aromaticum): EXTRAÇÃO, CARACTERIZAÇÃO E ATIVIDADE LARVICIDA FRENTE AO Aedes aegypti (Linnaeus, 1762)
(Universidade Federal do Maranhão, 2012-05-04) Nascimento, Alexandre Albuquerque do; MOUCHREK FILHO, Victor Elias; CPF:70434212415; http://lattes.cnpq.br/2381183158978639
In this work, from the extraction and analytical study about the essential oil of the flower buds of Syzygium aromaticum species, was analyzed the larvicide effect of the oil against larvae on the third stage of the mosquito Aedes aegypti (Linnaeus, 1762). The essential oil was extracted, quantitatively, by hydrodistillation. The physical-chemistry properties of the essential oil were determined (Density, refractive index, solubility, color and appearance). The oil was characterized, chemically, quantifying its components and identifying its major component by gas chromatography coupled to the mass spectrometry. In this research was calculated the oil CL50 and its eugenol standard, besides the confidence limit to 95% of probability, using the methods of Reed-Muench (1938) e Pizzi (1950), respectively. The oil yield was 3,54% m/m and 3,63 v/m. Through the method used was possible identify and quantify the components: Eugenol (52,53%), caryophyllene (37,25%), humulene (4,11%), eugenila acetate (4,05%) and copaene (2,05%), eugenol is the major oil s component. The oil exhibited larvicidal activity being totally lethal at concentration of 120 µg.mL-1. The essential oil obtained CL50 of 63,36 (±2,12) µg.mL-1 and an Eugenol standard 79,39 (±2,10) µg mL-1. The promising results point to need of more researches with the oil to its subsequent utilization in the combat of Aedes aegypti larvae.
OXIDAÇÃO ELETROCATALÍTICA DE HIDRAZINA EM MEIO ÁCIDO POR HEXACIANOFERRATO DE RUTÊNIO(III)
(Universidade Federal do Maranhão, 2012-07-05) Costa, Wendell Mesquita; MARQUES, Aldaléa Lopes Brandes; CPF:07648626349; http://lattes.cnpq.br/0121030502015990; Tanaka, Auro Atsushi; CPF:00548204802
A ruthenium (III) hexacyanoferrate film was anchored with Nafion® on the surface of a glassy carbon electrode and tested in Britton-Robinson buffer ionic strength of 0.1 mol L-1 and pH = 1.8 at room temperature. The cyclic voltammograms of the electrode with the film showed four pair peaks with a surface-confined characteristic and they also indicated that the film is strongly dependent on the solution pH. The ruthenium (III) hexacyanoferrate film showed an excellent electrocatalytic activity toward the oxidation of hydrazine. The electrocatalytic oxidation of hydrazine was studied by cyclic voltammetry, rotating disk electrode voltammetry and chronoamperometry techniques. It has been observed that the oxidation of hydrazine to nitrogen occurs at a potential where oxidation is not observed at the bare glassy carbon electrode. The overall number of electrons involved in the catalytic oxidation of hydrazine was determined by cyclic voltammetry and rotating disk electrode experiments. A Tafel plots indicated a one-electron charge transfer process to be the rate-limiting step and the overall number of electrons involved in the catalytic oxidation of hydrazine was found to be four. It has been shown that the catalytic oxidation of hydrazine obeys fist-order kinetics with respect to hydrazine concentration. The diffusion coefficient of hydrazine was also estimated using chronoamperometry, presenting a value of 1,2 x 10-5 cm2 s-1.
EXTRAÇÃO, CARACTERIZAÇÃO E AVALIAÇÃO DA ATIVIDADE LARVICIDA DO ÓLEO ESSENCIAL DO Citrus limon Linneo (LIMÃO) FRENTE AO MOSQUITO Aedes aegypti
(Universidade Federal do Maranhão, 2013-03-11) Oliveira, Marlucy Bezerra; MOUCHREK FILHO, Victor Elias; CPF:70434212415; http://lattes.cnpq.br/2381183158978639; Silva, Gilmar Silvério da; CPF:10011120100; http://lattes.cnpq.br/6983165980341102
Surveys show that the resistance of the larvae of Aedes aegypti to synthetic pesticides, have boosted demand for alternative chemical compounds of natural origin to combat the dengue vector. In this work, from the extraction and analytical study of the essential oil of the pericarp of the Citrus limon Linneo, the larvicidal effect of the oil against larvas in third phase of the mosquito Aedes aegypti (Linnaeus, 1792) was analyzed and based on the analytical result was evaluated the effect of the major compound. The essential oil was extracted quantitatively by hydrodistilation. The essential oil physical-chemical proprieties (density, refraction rate, solubility, color and appearance) was determined. The oil was analytically characterized by infra-red (FTIR) and gas chromatography coupled to spectrometer of mass (CG-EM). The oil s CL50 was calculated from the Reed-Muench (1938) and Pizzi (1950) methods, respectively. The oil yield was 0,52% m/v. 18 components were identified in the oil, and the major presence of l-limoneno was confirmed by the spectroscopic technics. The essential oil got CL₅₀ 14,99 (±2,25) μg mLˉ¹ and l-limonene of 26,73 mg mLˉ¹ (± 2,02) mg mLˉ¹ and the d-limonene 113,24 mg mLˉ¹ (± 2,02) mg mLˉ¹. The results indicate that the essential oil evaluated is compound by substances that propitiate larvicidal effect against Aedes aegypti.
COMPARAÇÃO DE SENSORES ELETROQUÍMICOS PARA DETERMINAÇÃO DE ENXOFRE EM BIODIESEL
(Universidade Federal do Maranhão, 2013-06-06) Costa, Helmara Diniz; MARQUES, Edmar Pereira; CPF:03241645304; http://lattes.cnpq.br/2468528554511482; Santana, Sirlane Aparecida Abreu; CPF:29246970349; http://lattes.cnpq.br/1052349578152491
Due to the implementation of more restricted environmental regulation laws, the control of pollution agent such as sulfur compounds has provides the development of new analytic methodologies for its quantification on different matrices, including biodiesel fuel. Thus, this work aims to compare three different sensors - film bismuth and mercury film on the surface of a glassy carbon electrode and solid silver amalgam (dental) - for the determination of sulfur in biodiesel, by means of stripping voltammetric cathodic square wave mode (VRC/SW) as supporting electrolyte with a solution of sodium acetate (1,4 mol.Lˉ¹) and acetic acid (0.33 mol.Lˉ¹) in metanol/2-propanol. In general, the mercury film electrode (MFE) has presented the best electrochemical behavior to the definition of peak reduction, being then selected as standard electrode to the measurements. The sulfur quantization on biodiesel samples was performed by adding 70 μL of soybean biodiesel and tallow fatty with TMAH, adding later, aliquots of standard sulfur. The method showed good linearity (0.998), suggesting an average sulfur concentration of 6,870x10ˉ7 (± 6,857x10ˉ⁸) mol.Lˉ¹, within a confidence interval of 95%, to a limit of detection 3,294x10ˉ¹º mol.Lˉ¹ and quantification limit of 1,098x10ˉ9 mol.Lˉ¹. Besides, for the untreated sample, the experimental has provided a LD of 6,54 x 10ˉ9 mol.Lˉ¹. Finally the proposed method has been compared with the results of a collaborative study (ANP 01/2012) of the same sample using the Teste-t de Student, verifying that the proposed method and official methods (EN ISO 20846, EN ISO 20884) are statistically equivalent to a confidence level of 95%, thereby demonstrating the feasibility of the method.
AVALIAÇÃO POR ESPECTROSCOPIA DE IMPEDÂNCIA ELETROQUÍMICA DO EFEITO CORROSIVO DE BIODIESEL PURO E MISTURAS EM ALUMÍNIO
(Universidade Federal do Maranhão, 2013-06-07) Cordeiro, Cristiane Italiano; RODRIGUES, José Roberto Pereira; CPF:37536001304; http://lattes.cnpq.br/6186580867262823; Maciel, Adeilton Pereira; CPF:92935427491
The use of biodiesel as fuel has presented a great potential in the world, both for its contribution to the environment as well as for being a fuel derived from renewable sources. However, this fuel is causing serious problems of corrosion metallic in materials used in diesel engines, transport systems and storage. In this sense, the present work aims, evaluating the corrosive effect of biodiesel and mixtures in aluminum by means of electrochemical techniques, as the open circuit potential and impedance electrochemical spectroscopy. For such, were used aluminum blades immersed in samples of B100 biodiesel and mixtures of B5 and B4, was also used microemulsion samples for obtaining better answers in the electrochemical trials. The surface of the metalic material was evaluated, after immersion trials, by visualization the optical microscope, in order to identify the effect caused by corrosion. The results obtained for trials showed that aluminum presented a good corrosion resistance in contact with the fuel samples, as well as in samples microemulsion.
INFLUÊNCIA DA TEMPERATURA E DE MATERIAIS PARTICULADOS NA PRECIPITAÇÃO DOS ASFALTENOS
(Universidade Federal do Maranhão, 2013-10-04) Almeida, Iratã Charles Ribeiro; ROLEMBERG, Marlus Pinheiro; CPF:72192119453; http://lattes.cnpq.br/1520599055684991; Tanaka, Auro Atsushi; CPF:00548204802
The oil´s behavior s study, mainly the hard fractions, including asphaltenes and resins, have became extremely important, since the relations between theses constituents during the oil mixing operations and its derivatives may bring several problems with the asphaltenes precipitance. Undesirable, the precipitance may cause pipe s obstruction during the oil s extraction, slowing down the production and rising up the expenses. These facts have motivated this work, that seek determine the influence of temperature and adding particulate materials, in the beginning of asphaltenes precipitation (IP) in models solutions, intending in better characterize the precipitation process, once many of the models applied to determinate the stability and compatibility between these oils, for example, are based on data from the beginning of the precipitation (IP). The technique spectroscopy near Infrared was used to determine the precipitation of asphaltenes in the temperature range from 10 to 30 ºC and with different particle materials (calcareous, sandstone, clay) and a optical microscopy technique determining IP with no temperature variations, contributing as basis for the obtained value, using the NIR technique. The results will designate the temperature variation, with little influences on precipitation, according to the literature. Particle adding (calcareous and clay) have proved to be significant, modifying significantly the asphaltenes precipitation outset, however, the same thing hasn t been noticed with the sandstone particles.
DISTRIBUIÇÃO E FRACIONAMENTO DE FÓSFORO EM SEDIMENTOS DE MANGUEZAIS DO ESTUÁRIO DO RIO TIBIRI NA ILHA DO MARANHÂO, REGIÃO AMAZÔNICA
(Universidade Federal do Maranhão, 2013-10-25) Jesus, Edson Tobias de; SILVA, Gilmar Silvério da; CPF:10011120100; http://lattes.cnpq.br/6983165980341102; Mouchrek Filho, Victor Elias; CPF:70434212415; http://lattes.cnpq.br/2381183158978639
In order to assess the environmental impact and the behavior of phosphorus in the sediments of mangrove Tibiri River on the Maranhão island, five phosphorus fractions were determined (TP, IP, OP, AP) and NAIP in mangrove sediment, through sequential extraction according to the protocol of the European Commission (SMT - standards, measurements and testing Programme). Concentrations of the majority metals were also determined (Ca , Al , Mg , Fe and Mn) by inductively coupled plasma atomic with optic emission spectrometry (ICPAES) in the same extracts of cited above, moreover, mineralogical analysis of the mangrove sediment was made by X-ray diffraction. Sediments form Tibiri River showed phosphorus levels in the order of 341.44 mg.kg-1, characterized as an estuary with inexpressive impact of anthropogenic activities. Most phosphorus is found in the non-apatite inorganic fraction, (NAIP), mean 70%. The inorganic fraction of phosphorus, such as apatite mineral (PA) remained at 29%. Rio Tibiri was classified as unpolluted (PT < 500 mg kg-1), although most phosphorus is found as labile (mean 73.68%). Among the majority metals, Ca stood out by its association with the apatite fraction (AP), Corroboratig the presence of this mineral in the sediment. The main clay minerals found were kaolinite, montmorillonite , illite and quartz.
ESTUDO DA COMPOSIÇÃO E APLICAÇÃO DO ÓLEO ESSENCIAL DE Origanum vulgare L. COMO AGENTE ANTIMICROBIANO EM SURURU (Mytella falcata).
(Universidade Federal do Maranhão, 2013-11-29) Liston, Mariane da Silva; MOUCHREK FILHO, Victor Elias; CPF:70434212415; http://lattes.cnpq.br/2381183158978639; Nascimento, Adenilde Ribeiro; CPF:10455825300
Essential oils (OEs) are natural plant extracts and many of them are active as antimicrobials. Origanum vulgare L. (oregano) essential oil (OEO) has a promising application field as a food preservative. Several in vitro and application studies has been carried to evaluate the activity of OEs as antimicrobials in foods, but are not found in the literature survey data application in mussels. In this study we evaluated the chemical composition and the antibacterial effect of OEO in fresh chilled mussels from Mytella falcata species. The chemical constituents of the studied OE were identified by gas chromatography-mass spectrometry and for activity we analyzed the count of Escherichia coli and aerobic mesophilic bacteria, total volatile bases and pH. The addition of OEO at 1.4% resulted in complete inhibition of E. coli inoculated, reduced growth aerobic plate count bacteria and inhibit the process of deterioration. The activity of the OEO is attributed mainly to its major component, carvacrol, which has recognized antibacterial activity. The results indicate that the OEO can be applied to support of the extension of shelf life and safety of fresh mussels.
DETERMINAÇÃO ESPECTROFOTOMÉTRICA DE DICLOFENACO DE SÓDIO EM FORMULAÇÃO FARMACÊUTICA EMPREGANDO O CONCEITO DE FIA-MULTICOMUTAÇÃO
(Universidade Federal do Maranhão, 2014-03-28) Gomes, Paulo Roberto Barros; FERNANDES, Ridvan Nunes; CPF:00062700300; http://lattes.cnpq.br/9020022655425615; Silva, Gilmar Silvério da; CPF:10011120100; http://lattes.cnpq.br/6983165980341102
International and national bodies require the development of analytical methods that are rapid, inexpensive and accurate for the determination of drugs. One way to meet these requirements a method of flow injection analysis employing multicommutation and spectrophotometric detection was used. In this paper an automated system was developed to determine diclofenac sodium in injectables. The reaction is based on the oxidation of diclofenac sodium with potassium permanganate in acid medium be-ing monitored at 465 nm this. The calibration curve was linear over the concentration range of 20-80 mg Lˉ¹ with a detection limit of 0.1 mg Lˉ¹ standard deviation of 0.9% (n = 20) and Sample Rate 80 samples per hour. The proposed method was applied successfully in three injectable solutions and the samples were compared with the official method and other automated methods employing the same reaction.
DESENVOLVIMENTO E APLICAÇÃO DE METODOLOGIA ANALÍTICA (CLAE/FL) PARA DETERMINAÇÃO DE FLUOROQUINOLONAS EM SEDIMENTO ESTUARINO DA ILHA DO MARANHÃO
(Universidade Federal do Maranhão, 2014-12-19) Neves, Mônica Araujo das; Marques, Edmar Pereira; CPF:03241645304; http://lattes.cnpq.br/2468528554511482; SILVA, Gilmar Silvério da; CPF:10011120100; http://lattes.cnpq.br/6983165980341102
Drugs in the planet have increased during last decades. Such compounds can cause adverse impact on ecosystems. Soon, more effective analytical methods are essential for the study of new pollutants, especially in magazines whose headquarters are very complex as mangrove sediments. Therefore, this study aimed to improve an analytical method to assess the occurrence of fluoroquinolone antibiotics, ciprofloxacin (CIP), levofloxacin (LEV) and norfloxacin (NOR), in sediment samples from the Paciência river located on the Maranhão island using the technique of ultrasound-assisted extraction, extraction phase solid and liquid chromatography (HPLC/FD). According to the study, the method was linear (r²> 0.99), recovery ranging from 73.73 to 88.85%, precise (RSD <20%), selective and sensitive (detection limit for CIP, LEV and NOR 9.32; 17.78 and 4.42 µg.kgˉ¹, respectively, and limit of quantitation of 20 µg.kgˉ¹ for all three drugs) for quantification of fluoroquinolones in estuarine sediments. Other relevant aspects of the method developed in this work were the simplicity, low cost and absence of interfering to a very complex environmental matrix as are the mangrove sediments. When evaluating the sediment at various points of the river there was contamination at three points by CIP ranging from 56.55 to 70.45 µg.kgˉ¹ These results are similar to those found around the planet to polluted regions and they are of concern due to the effects of these antibiotics in the ecosystem.

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