Marcos Roberto Monteiro

Evaluation of biodiesel-diesel blends quality using 1H NMR and chemometrics.

In this work, the use of (1)H NMR spectroscopy and statistical approach to the evaluation of biodiesel-diesel blends quality is described. Forty-six mixtures of oil-diesel, biodiesel-diesel, and oil-biodiesel-diesel were analyzed by (1)H NMR and such data were employed to design four predictive models. Thirty-six mixtures were used in the calibration set and the others in the validation. The PCR and PLS models were evaluated through statistical parameters. Briefly, PLS and PCR models were suitable for the prediction of biodiesel and oil concentration in mineral diesel. Specially, in higher concentration the predicted values were quite similar to the real ones. This fact was evidenced by the low relative errors of high concentrated samples; this means that the prediction of low concentrated samples will probably show high deviation. Therefore, (1)H NMR-PLS and (1)H NMR-PCR methods are fairly useful for the quality control of biodiesel-diesel blends, particularly they are suitable for prediction of concentrations greater than 2%.

Desenvolvimento de compósitos poliméricos com fibras vegetais naturais da biodiversidade: uma contribuição para a sustentabilidade amazônica

This paper presents the research on Polymeric Composites with Natural Fibers in the Amazon Fenix Project. Two research and development fields based on polymeric composites with natural vegetable fibers are proposed: the first one considers production systems with simple, cheap machinery to facilitate technology assimilation by rural communities in the Amazon; the second one aims at developing composite materials with advanced production technology. It is hoped to raise awareness for scientific and technological development for the recovery of degraded areas in Amazon.

Corrosão metálica associada ao uso de combustíveis minerais e biocombustíveis

Fuels and biofuels have a major importance in the transportation sector of any country, contributing to their economic development. The utilization of these fuels implies their closer contact to metallic materials, which comprise vehicle, storage, and transportation systems. Thus, metallic corrosion could be related to fuels and biofuels utilization. Specially, the corrosion associated to gasoline, ethanol, diesel, biodiesel, and their mixtures is discussed in this article. Briefly, the ethanol is the most corrosive and gasoline the least. Few investigations about the effect of biodiesel indicate that the corrosion is associated to their unsaturation degree and the corrosion of diesel is related to its acidity.

Evaluation of Metallic Corrosion Caused by Alcohol Fuel and Some Contaminants

In the present work, it is evaluated the effect of water and other contaminants of alcohol fuel on the corrosion behavior of different materials, which can constitute vehicles, storage and transportation fuels systems. For such, 5 metallic materials (zamak, low-carbon steel, stainless steel, and two Al alloys) were chosen and 5 alcoholic solutions were prepared: anhydrous ethanol (AEAC; solution 1); hydrated ethanol (AEHC; solution 2); AEAC and water with some impurities (AEAC + 6 % “corrosive” water; solution 3); AEHC and water with some impurities (AEHC + 6 % “corrosive” water; solution 4); and, AEAC and tap water (AEAC + 6 % tap water; solution 5). The crevice corrosion was investigated in static immersion tests, which were carried out at 50 °C for 2 months. The evaluation of the corrosive process was carried out by visual inspection, weight loss, optic microscopy, and scanning electron microscopy (SEM). Also, some quality parameters of the alcoholic solutions (specific mass, alcoholic content, pH, and conductivity) was analyzed in order to determine the influence of corrosion of the materials on them. The results have shown that crevice corrosion of all materials mostly occurred in solutions 3-5, which had a high amount of water and impurities. Some corrosion rates in such solutions were 90-400 times higher than those obtained in AEAC and AEHC. Among the materials, zamak and carbon steel suffered severe corrosive attack. The physicochemical properties of alcoholic solutions employed in the tests also changed, mainly the increase of pH and conductivity was observed. Therefore, the results demonstrate that the quality control of alcohol fuel is essential in order to avoid the damage of engine parts and storage and transportation systems. Specially, water, sulphate, chloride and acetate content must be monitored.

Trypanocidal activity of quinonemethide triterpenoids from Cheiloclinium cognatum (Hippocrateaceae).

We report the trypanocidal activity of quinonemethide triterpenoids isolated from root extracts of Cheiloclinium cognatum, a plant of the Hippocrateaceae family, collected in the Cerrado Reserve at Universidade Federal de Goiás, Brazil. The trypanocidal activity assays showed an effect on the blood trypomastigote forms of the Y strain of Trypanosoma cruzi where tingenone and tingenol demonstrated activity on the parasite. Their structures were elucidated on the basis of spectral data, particularly COSY, HMQC and HMBC experiments, and chemical transformations

Evaluation of Vulcanized Elastomeric Composites after Ageing in Biodiesel

The incorporation of biodiesel in the worldwide energetic matrix has an increasing tendency to use in the world. However, there are many technological challenges to consolidate this biofuel as an alternative to fossil fuels. The evaluation of the materials compatibilities used in the automotive industry and biodiesel production chain has been configured as an important area of research in finding appropriate materials that comes into contact with diesel biodiesel/blends. The present work aims to evaluate the physical properties for elastomeric composites prepared with polymeric matrix of ethylene propylene diene monomer (EPDM), acrylonitrile-butadiene rubber (NBR), natural rubber (NR) and styrene-butadiene rubber (SBR). The composites were prepared under controlled conditions of mixing and vulcanization. The elastomeric composites were aged in a blend containing 95 vol% of diesel and 5 vol% of biodiesel (B5 blend). The static total immersion tests were carried out at controlled temperature (50°C) for 7, 14, 21 and 28 days, substituting the B5 blend every 7 days. The results showed that the properties of NBR are less affected than other elastomers. It showed better mechanical performance and less influence on the glass transition temperature, indicating less degradation of this rubber in contact with B5 blend used in immersion tests.

DESI-MS imaging and NMR spectroscopy to investigate the influence of biodiesel in the structure of commercial rubbers

Biodiesel has been introduced as an energetic matrix in several countries around the world. However, the affinity of biodiesel with the components of petrodiesel engines is a growing concern. In order to obtain information regarding the effect of biodiesel on the rubber structure, nuclear magnetic resonance technics under a new technology named as comprehensive multiphase (CMP NMR) and the imaging through desorption electrospray ionization mass spectrometry (DESI-MS imaging) were used. The 1H CMP-DOSY NMR showed the entrapped fuel into the rubber cavities, which the higher constraint caused by the rubber structure is related to the smaller diffusion coefficient. The less affected type of rubber by biodiesel was ethylene-propylene-diene monomer (EPDM), and the most affected was synthetic rubber nitrile (NBR). The 13C CMP MAS-SPE experiments also confirmed that the internal region of EPDM was less accessible to the biodiesel molecules (no fuels detected) while other rubbers were more susceptible to the penetration of the fuel. DESI-MS imaging revealed for the first time the topography of the rubbers exposed to fuels. The biodiesel molecules entrapped at the EPDM and NBR pores were in oxidized form, which might degrade the rubber structure at long exposure time. The employed technics enabled the study of dynamic and molecular structure of the mixing complex multiphase. The DOSY under CMP used in this study could prove helpful in assessing the interactions throughout all physical phases (liquid, solid, and gel or semi-solid) by observing swellability caused by the fuel in the rubber. In addition, the DESI-MS was especially valuable to detect the degradation products of biodiesel entangled at the rubber structure. In our knowledge, this was the first report in which chemical changes of commercial rubbers induced by biodiesel and petrodiesel were investigated by means of DESI-MS and DOSY NMR.