RCAAP Repository

SnO2 pigments, when doped with chromium, lead to violet or purple colors, depending on chromium oxidation state. There is a need to control the chromophore oxidation state, as Cr(VI) is toxic and carcinogenic, while Cr(III) leads to no risk to living beings. Cr(VI) formation may be avoided with the addition of counterions, that lead to a charge imbalance. In this work, SnO2:Cr pigments were synthesized by the polymeric precursor method, with the addition of molybdenum as counterion. The powder precursor decomposition was evaluated by thermogravimetry (TG) and differential thermal analysis (DTA). The influence of the counterion in the crystalline structure was evaluated by Xray diffraction. The materials were also characterized by infrared spectroscopy, colorimetry and UV-vis spectroscopy. All pigments are crystalline and single phase with cassiterite structure. Chromium formation with hexavalent state was observed in all samples, while Sn0.90Cr0.06Mo0.04O2 presented the lowest amount of this cation, comparing to the other pigments, being the less toxic one. Violet and rose colors were obtained for materials doped with chromium and chromium/molybdenum, respectively, being related to the formation of Cr(IV) in the material structure.

This work proposes the use of digital images captured by a Webcam for determination of total acidity in red wines by means of an acid-base titration without using an external indicator. Digital images present the colour of the emergent radiation, which is complementary to the radiation absorbed by molecules of anthocyanines presents in wines. Each image, generated according to RGB system, yields a matrix of the values of the R, G and B components whose averages define a the colour value obtained as: 2R ⋅2G ⋅2B. This value was adopted as analytical response to build titrations curves based on digital images (DIB). For a more precise localization of the end point, titrations curves were generated on the basis of the second derivative values of the analytical response. Anthocyanines present different colours according to medium pH and, from the variation of the colour values of the images obtained during the titration of the red wines, the end point could be detected with precision. The official method recommends the use of potenciometric titration for determination of total acidity in red wines. This method requires a dilution of the sample before the titration that must be carried out until a fixed value of pH (8.2 8.4). In order to illustrate the feasibility of the proposed method titrations involving the determination of total acidity in ten red wines samples were carried out. Results were compared to the ones obtained by potenciometric titration used as reference method. No statistic difference has been observed between the results by applying the paired t-test at 95% confidence level. The proposed method yielded results with a better precision than the official method. These advantageous characteristics are attributed to the trivariate nature of the measures associated to digital images.

The major purposes for the production and use of biodiesels are environmental, social and economic benefits. However the production of 90 cubic meters of biodiesel generates about 10 cubic meters of glycerin, so partial or total replacement of diesel by biodiesel can because of glycerin generate a lot of problems. A great surplus (without market), could force the devaluation of its price, and glycerin factories losing competitiveness might be forced to close down. However the world is in a race to develop new processes and add new technologies for the rational use of bio-fuel co-products like glycerin. This study obtained "New Materials" by using glycerin with applicability to biology, diesel fuels, and bio-fuels with cetane improvers. We obtained five organic nitrates characterized as 2-nitrate-1,3-diethoxypropane (NDM); 2-nitrate-1,3- dimethoxypropane (NDE); 2-nitrate-1,3-dipropoxypropano (NDP); 2-nitrate-1.3-dibutoxypropano (NDB) and (+/-)-2,2-dimethyl-1,3- dioxolan-4-metilnitrato (nitrate solketal - NSKT). pharmacological evaluation showed that the nitrates of diesters have hypotensive activity on the cardiovascular system revealing NDB as the compound that showed greater potency and effectiveness against the vasorelaxant effect in the superior mesenteric artery isolated from rats in the order of 115.58 ± 5.59. The nitrate solketal ((+/-)-2,2-dimethyl-1,3-dioxolan-4-metilnitrato) (NSKT) was tested as a cetane improver for biodiesel so as to obtain a new low cetane bio-fuel. The addition of NSKT 7% to ethanol, formed a low cetane fuel capable of operating diesel engines.

This study aimed to investigate major metabolites from the aerial parts of Ocimum basilicum by a phytochemical screening. Quantitatively extracting the essential oil and subjecting it to thermal analysis and chromatography, as well as verifying its performance as an antioxidant, antibacterial and larvicidal agents. In this study it was observed that the aerial parts of Ocimum basilicum present tannins, depsides and depsidons, free steroids, flavonoids, saponins, flavonoid aglicons, triterpenoid aglicons, steroids and organic acids. The yield of essential oil extracted varied between 1.5 and 2.0% for the dried aerial parts, while the one of fresh aerial parts was between 0.28 to 1.0%. The study of essential oil plant species by gas chromatography coupled with mass spectrometry, revealed that the essence of it consists of six components, metilchavicol, linalool, eucaliptoll and farnesene, the main metabolites. The thermal study of the essential oil made by termogravimetry in air atmosphere and nitrogen, showed a similar thermal profile, indicating two mass loss attributed to volatilization of terpenes fraction and decomposition of aromatic fraction respectively. Antioxidant, antibacterial and larvicidal analysis revealed that the essential oil from dried aerial parts of Ocimum basilicum has outperformed the essential oil of fresh aerial parts when tested under the same conditions.

This work describes the construction of a new flow-batch analyzer (FB) in micro scale (micro Flow-Batch-μFBA) using the technique of deep ultraviolet photolithography with commercial resin based in urethane acrylate oligomers (UA). The device was constructed from the union of two layers of pre-polymerized resin of 3.4 mm thick each, thus forming a single structure. The main feature of the new device is the small volume of its analysis chamber, which can be 100-200 μL, allowing the homogenization of reagent solutions in a time of 2.s. In this sense, the decrease in reagents consumption and hence generation of waste (ten times smaller than a conventional FB), wich is in line with the requirements of green chemistry and with the new position of the eco-efficiency. The system offers the following progress in relation to micro fabrication with urethane acrylate resin: (i) depth control of the channels during photolithography; (ii) axial mixer incorporated; (iii) LED - Light emitting diode (530 nm) and detector (photodiode) coupled to the device body; The depth control of the channels allows adjustment of the volume of the chamber and the LED to the mixing chamber. The LED and detector connector pins is the elements that makes the device fixed on its box. In this first assembly, system were used in photometric determination of Fe (II) in pharmaceuticals. The model for the calibration curve was validated by analysis of variance (ANOVA), and their analytical results were compared with those obtained in batch by the reference method, the application of paired t-test found no statistically significant differences at a confidence level of 95%.

The selective leaching of clay minerals is an important method in the preparation of porous silicates presenting as a simple, effective and low cost route. In this study, vermiculite was submitted to acid treatment at concentrations 1, 2, 3, and 4 mol dm-3, resulting the precursor solids named as VacX (x=1 a 4), respectively. The lixiviated matrices and vermiculite reacted covalently with the organosilanes aminepropyl-, propyletilenediamine-, propyldietilenetriamine- and glycidoxypropyltrimethoxisilane (GPTS). The hybrid Vac3G, derived from silanization reaction between Vac3 and GPTS, was submitted to subsequent reactions with ethyl, propyl, butyldiamines and 2- aminepiridine resulting in the entrance of new basic centres. The products were characterized by chemical analysis, infrared spectroscopy, X-ray diffraction, 29Si and 27Al NMR in solid state, SEM, and pore volume and surface area determination. The lixiviation of sodic vermiculite originated the restructured porous solids with high superficial area showing the values133, 334, 673 e 575 m2 g-1 for VacX where X = 1,2,3,4, respectively. These solids and sodic vermiculite reacted covalently with each organosilane through methoxyl groups of silane and the hydroxyl surface of matrices. Independently of solid, it was observed that the lixiviation favored the reactivity of activated matrices compared with sodic vermiculite, showing the Vac3 as more reactive comparing with others solids. All modified solids presented high nitrogen content showing the values of 6,31 %. The set of modified vermiculites containing aminepropyl group was applied as adsorbent for divalent cations as copper and nickel in aqueous solution. These solid showed highest affinity for Ni2+ than Cu2+ ions as illustrated by Nf values of 2,97 and 1,23 mmol g-1, respectively. Clay porous solids obtained of leaching treatment of vermiculite are potential substrates for grafting of silanes showing important applications as adsorbents for contaminant species as heavy metals.

The aim of this research was to study the chemical and physical properties of the papaya seeds of three different cultivars produced in Brazil: Sunrise Solo (Hawaii), Golden and Formosa. The chemical composition of the seeds and the extracted oils, physical chemical properties of oils and obtained biodiesel were analyzed to evaluate the industrial use of this disposable residue as renewable energy source. Golden and Solo Sunrise cultivars presented lower fruit weight (391.92 and 590.32 g) compared to Formosa cultivar (1318.16 g) but a higher seed yield of 2.54 and 1.43% respectively against 0.61% of Formosa. The chemical composition of the seeds shown high protein content (23.58 to 25.46 g/100 g), fibers (16.07 to 19.19 g/100 g) and minerals (5.12 to 6.48 g/100 g) among the three cultivars with emphasis on Fe and P (104.18 mg/g and 634.12 mg/g) for the cultivars Golden Sunrise Solo cultivars. The oil content was ± 28%. The major component were oleic acid (69.78%, 70.13% and 72.04%) and palmitic acid (18.95%, 18.89% and 18.20%) respectively for Golden, Sunrise Solo and Formosa cultivars. The acidity index (1.0, 0.98 and 1.03), iodine index (71.30, 70.26 and 70.45) and saponification index (190.2, 190.14 and 189.98) were found form the three papaya variety. Methyl transesterification of the Golden oil was carried out by 0.5% basic catalysis, 1:8 molar ratio, 45°C temperature and the product was identified by TLC, GC-MS, IR and 1H and 13C NMR techniques. The yield of the methyl esters (92.07%), was gravimetrically determined according to the stoichiometry of the reaction. The kinetics of acid catalyzed methyl transesterification using the same oil was evaluated by TLC and the yield of esterification was determined by reducing the acidity index of the reaction medium. The reaction medium used and results found were: 1:9 molar ratio and 80°C temperature the acidity index was reduced from 28 to 3.31 and 3.12 mg KOH/g sample, yielding of 88.18% and 88.86% respectively, at 1.0 and 1.4% catalyst after 8 hours of reaction. In a second stage of the reaction after 2 hours, the acidity index were 1.8 mg KOH / g (1.0% of catalyst) and 1.6 g KOH / g (1.4% of catalyst) with esterification maximum respectively 93.57 and 94.28%. The biodiesel obtained by basic catalysis showed 0.35 mg KOH / g acidity value, 0.88 g/cm3 density, 6.0 mm2 / s kinematic viscosity, 1°C cloud point, -1°C flow point and 62.83 cetane number. The power generation consumption, in L / h, were 0.5837 (B100), 0.5806 (B50), 0.5814 (B20), 0.6122 (B10), 0.6225 (B5) compared to 0.6981 (diesel), indicating its high calorific power. Thermal stability studies showed that the initial temperature of mass loss in TGA (155 ° C) match with the temperature variation of enthalpy by DSC curve and the initial oxidative event shown in non-isothermal curve PDSC indicating superior thermo-oxidative stability comparing to Soybean biodiesel where similar thermal events begin at a temperature of 100 º C. The oxidative stability (25 hours) was evaluated by Rancimat test. This result was confirmed by PDSC, where the variation of the baseline occurred at 54 minutes after reaching the temperature of the isotherm, at 110°C, and any other thermal event was observed during the entire period of the experiment (10 hours), indicating no oxidation reactions. The peroxide index was evaluated 58.4 meq / kg by using an oven (65 ºC) for a period of 25 days, showing a high stability if compared with the sunflower oil biodiesel, which according to the literature and in the same procedures presented a peroxide index of 300 meq / kg in seven days. The rheological study showed a Newtonian behavior and an absolute dynamic viscosity of 5.3 ± 9.1.10-5 m.Pa.s.

Biodiesel is composed by a mixture of different kinds of esters that may have unsaturations in their chains. These unsaturations are susceptible to oxidation processes, especially in the presence of oxygen. The oxidative stability of biodiesel becomes therefore an important quality parameter since the oxidation of the esters may cause some problems when using this fuel. In the search for new technologies to solve this problem, this study used the phenolic substances (cardanol and eugenol) extracted from the liquid cashew not and clove and BHT also phenolic compound, for testing antioxidants in biodiesel cotton. It was made structural changes (hydrogenation) in the compounds cardanol and eugenol to eliminate sites of oxidation (unsaturated) and also increase the initial temperature of decomposition. The results showed that the hydrogenation with an increase in the initial decomposition temperature of 112.70 ° C to 207.80 º C to cardanol and 160 ° C to 175 º C in the case of eugenol. The antioxidant activity of BHT, hydrogenated eugenol and cardonal was detected in combating oxidative bioidesel of cotton during 180 days of storage. We choose cotton biodiesel because oil composition show a high content of unsaturated fatty acids (C16: 1 = 0.20% C18: 1 = 24.30%, C18: 2 = 44.40% and C18: 3 = 5.40%). The test results of the peroxide, iodine, acidity, viscosity and UV-vis spectroscopy showed the following order of activity for the tested compounds: eugenol hydrogenated> cardanol hydrogenated> BHT. This same order of activity was observed when used techniques such as, accelerated oxidation colorimetry exploratory differentiates (PDSC) and PetroOxy. The kinetics of oxidation of the samples doped with the respective compounds reaffirms the same order described previously.

The Brazilian biodiesel, whatever the source of their raw materials must meet some physical and chemical parameters that ensure their quality. A major problem associated with the use of biodiesel, especially prepared with castor oil, is its high viscosity that is outside the limit set by the ANP, becoming viable as fuel, only when used as a blend to diesel or other biodiesel with lower viscosity. The soybean biodiesel presents a high percentage of esters of polyunsaturated fatty acids being more susceptible to oxidation when compared to castor oil biodiesel. Within this context, the blends of ethylic biodiesel from soybean and castor oil (BsMx) in natura and in different storage conditions are promising in the correction of the flow properties and oxidative stability. The GC-MS results confirmed the presence of 42.45% of ethyl linoleate and 85.83% of ethyl ricinoleate for the ethylic biodiesel from soybean and castor oil, as major components, respectively. The infrared spectra showed increased content of castor oil biodiesel in the blend by more intense absorption at 3440.7 cm-1. The presence of ethyl ricinoleate in higher concentration in the blend conditioned the better oxidative stability, therefore, there was a decline in the pour point. Blends with proportions of until 30 and 57% were within the limit established by the ANP for kinematic viscosity and density, respectively. The condition and storage time of 120 days caused changes decreasing induction period and increasing the acidity index, water content and kinematic viscosity, being more evident for samples stored under light. During storage of 120 days, the density, the cold filter plugging point, the cloud point and the pour point were barely affected, with only a slight increase more pronounced for samples stored under light. Blends of ethylic biodiesel from soybean and castor oil allowed the use of oil in the composition of a new biodiesel (BSM) to be blended with diesel oil within the limits established by ANP for viscosity.

The present paper aimed at synthesizing, storing and monitoring biodiesel from the alkaline homogeneous transesterification of soybean oil and castor oil, using the methanol route, as well as evaluating the oxidative stability, during a 60 day-period, by means of the EN14112 standard. Blends of castor oil biodiesel and soybean oil biodiesel, containing 10, 20 and 30% v/v of castor oil biodiesel, respectively called M10, M20 and M30, were stored within illuminated and closed glass containers and later characterized. The physico-chemical analyses, performed for the two different biodiesel types and their blends, met most the requirements stated by the Technical Rule number 7 from the Brazilian National Agency for Petroleum, Natural Gas and Biofuels. The exceptions were the oxidative induction time (0.60 h) and the kinematic viscosity (13.98 mm2/s), which displayed values outside the limits established by the aforementioned agency. The blends displayed a higher oxidative stability than the pure soybean oil biodiesel, obtained by the methanol route. Thus, the blends with higher amounts of castor oil biodiesel, obtained by the methanol route, presented a higher safety, on the storage standpoint. The fluid-dynamic properties, cloud point, pour point and cold filter plugging point, pointed out similar behaviors for the blends and the pure biodiesels, obtained by the methanol route. Thus, in the studied concentrations, the castor oil methanol biodiesel acts as a natural additive for the soybean methanol biodiesel. By means of the EN 14112 standard, it was observed that the blend M30 is the one that is the most immune to the oxidation process, during the storage period of 60 days.

In this work, modified silica gel with the group aminopropiletanoimina was used as retention capacity for the ions cadmium, lead and cromate. The tests were accomplished in aqueous solutions under different conditions of pH, in constant temperature of 298±1 K. The number of mol of the organic chain anchored to the matrix was 0,97mmol /g. The analysis of the curves TG, for the degradation interval between 0,12 and 0,4, shows certain constancy of the value of the activation energy with the increase of the value of the conversion degree, however, the comparison of the activation energies calculated by the method of FWO and by the method of Coats-Redfern shows different results for all the models of simple mechanisms, for that, it is believed that the process in such area conversion doesn't happen through a simple mechanism, but through a complex process where more than one mechanism is acting in the dynamics of the degradation reaction. Based in the number of mols of cadmium, lead and cromate adsorbed, it can settle down the following order: cadmium > cromate > lead. The analysis of the kinetics of the reaction for the three ions shows that the processes of adsorption follow a kinetic law of speed of pseudo-second order with the constants of speed cadmium > lead > cromate. The balance of the process of adsorption is not described by the same model of adsorption; the lead and the cromate are described reasonably well by Langmuir, but for the cadmium it was not found any model to describe the behavior of the process of adsorption satisfactorily.

Jatropha curcas L. as a raw to produce biodiesel presents a promising alternative because of the perennial production of its fruits and a high oil concentration on its seeds. The mechanical extraction of the oil yielded 38% while the chemical extraction yielded 44.8% but the oil chemically extracted presented a higher acidity index, in relation to the mechanical extracted oil, factor that interferes in the transesterification reaction. The chromatographic data showed higher concentration of oleic acid (C 18:1) with 35,89% and linoleic acid (C 18:2) with 44,45%. The ethyl biodiesel was obtained through alcaline transesterification (KOH) and the 5%, 10% and 20% (m/m) biodiesel/diesel mixtures were prepared and then submitted to storage for 120 days, at room temperature. The results of RMN 1H and medium infrared characterized the ethyl biodiesel and its mixtures (B5, B10 and B20). The oxidative behavior of ethyl biodiesel and its mixtures were monitored through UV-Visible spectroscopy. The PetroOXY (OITB100= 52, 48, 35, 28 min) and P-DSC (HPOITB100= 41,30; 22,63; 7,72 min) techniques monitored the pure biodiesel s oxidative process and the results obtained indicate that oxidation occurred through the long period of storage. The cold hydrodynamic and flow properties confirmed the oxidative process, where was observed a slightly increase in viscosity, however the mixtures, although the biodiesel influence, after 120 days of storage kept into the required parameters by ANP regulations and consequently into commercialization conditions.

In this work, computational chemistry calculations and thermal analysis experiments were performed in order to determine the oxidative stability of four fatty acid methyl esters (stearate, oleate, ricinoleate and linoleate), whose fatty chains may be inserted in oils and biodiesel. In the computational chemistry investigation the sequence of stabilities, based on the dissociation energy of the C-H bond was: C18:2 < C18:1 < C18:1;12-OH < C18:0, for the B3LYP 6-31G(d) and MP2 6-311++G(2d,p); and C18:2 < C18:1;12-OH < C18:1 < C18:0, for the B3LYP 6-311++G(2d,p). The spin density analysis allowed stating that the ricinoleate hydroxyl does not act as a pro-oxidizing, as the radicals formed in C-12 or OH are not stabilized by the unsaturation in C9, showing, thus, the behavior of a secondary alkyl alcohol in relation to these sites, whereas their allylic hydrogen display an energy similar to the oleate hydrogens. In the experimental investigation carried out TG, it was possible to observe the formation of hydroperoxides by means of the mass gain in an oxygen atmosphere for oleate, linoleate and ricinoleate, but only volatilization for the stearate. In this investigation, a small heating rate (2 ºC/min) was utilized. The kinetic calculations based on PDSC, in the dynamic and isothermal modes showed that the oxidation susceptibility is quite dependent of temperature, atmosphere and the method employed, being more critical in relation to the methyl ricinoleate. In the dynamic mode, in an air atmosphere at 110ºC, the relative susceptibility was 1 : 17 : 17 : 226 (C18:0 : C18:1 : C18:1;12-OH : C18:2). In an O2 atmosphere this proportion was 1 : 11 : 1 : 102. In the isothermal mode PDSC, at the same temperature, the proportion was 1 : 1230 : 1585 : 23001 in an air atmosphere, and 1 : 33 : 40 : 445 in an O2 atmosphere. Performing a structure/property relationship, the oxidation temperature determined at a heating rate of 10 ºC/min was shown to be strongly correlated with the BDE (C-H) obtained by DFT and MP2, confirming the relationship between the first exothermic event of PDSC in the dynamic mode and the C-H bond strength. Therefore, PDSC is shown as a accelerated testing technique able to determine the true oxidative stability of lipids, as it supplies information on the rate controlling step of auto-oxidation (L-H + R1● → L● + R1-H), whereas the Rancimat method does not supply such information. Ternary ester blends were made and their oxidative stabilities were assessed by means of PDSC in a synthetic air atmosphere. Four equations were obtained with high linear correlation coefficients (R2 > 0.98). A biodiesel representation model was also developed, expressing its main oxidation sites and molecular descriptors for several physico-chemical properties. This representation is expressed by the molecular formula Ca Hb H*c Hd** He***(O2)f (0H)g and shows as one of its advantages the easy display of biodiesel data, what makes more evident the study of structure/property relationship. Its application for the four FAME s and twenty-three blends allowed determining the oxidation temperature (OT) in an air atmosphere, based on the descriptors for allylic hydrogen (H*) and bis-allylic hydrogens (H**). From such model a program in language C was elaborated, whose input is the FAME mole fraction and whose output is the OT in a synthetic air atmosphere. Keywords: Auto-oxidation, FAME (fatty acid methyl esters), Biodiesel, PDSC, DFT.

In the present work the molecular properties of heterocyclic hydrogen complexes: oxirane (C2H4O), methyloxirane (H3C-C2H3O) and hydroxi-oxirane (HO-C2H3O), as well as the respective ring open reaction by fluoridric acid has been investigated by using quantum chemistry methods. In this way, molecular properties of hydrogen complexes, such as oxirane---HF (C2H4O---HF), methyloxirane---HF (H3C-C2H3O---HF) e hydroxi-oxirana---HF (HO-C2H3O---HF), has been investigated as well. The quantum chemistry methods used were: ab initio (HF) and DFT (B3LYP and PBE1PBE) with the base set 6-311++G(d,p). The optimized structures for the hydrogen complexes and the reaction products were used in order to obtain the structure of the transition state and reaction path. The results yield that the mechanism for ring open involving the reagent HO-C2H3O-HF was kinetically and thermodynamically more favorable. The nucleofilic attack to the more substituted carbon is the preferential one. The reactivity order of the ring opened mechanism was: HO-C2H3O-HF > H3C-C2H3O-HF > C2H4O-HF.

The present work aims at investing the biodiesel obtained from the transesterification of sunflower oil by means of alkaline catalysis using 30% of ethyl alcohol, 1% KOH for each 100g of oil and (1:6) oil/alcohol molar ratio. The overall content of ethyl esters (99.72%) was determined by gas chromatography coupled to mass spectrometer, confirm the efficiency of the purification process carried out after the biodiesel synthesis. In the physico-chemical analyses, the results obtained complied with the standards allowed by the Technical Regulation No. 7 from the Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP). Thermal analyses were carried out with sunflower oil, diesel, sunflower ethanol biodiesel (B100) and its biodiesel/diesel blends, with proportion of 5, 15, 20, 25 and 50% biodiesel, employing the heating rate of 10 °C.min-1 in atmospheres of air and nitrogen, with runs up to 600 °C. The thermal decomposition of the samples was studied from the TG curves, aiming at assessing the order of thermal stability of the samples. The antioxidants α-tocopherol, BHT and TBHQ were added to the biodiesel samples aiming at assessing their efficiency in improving the thermo-oxidative stability of biodiesel. The techniques of pressure differential scanning calorimetry (PDSC) and Rancimat, revealed that the most indicated antioxidants for the storage of the ethanol sunflower oil biodiesel are BHT and TBHQ. However, even showing an antioxidant activity when added to the ethanol sunflower oil biodiesel, BHT was not efficient enough to increase the induction period to the minimum value of 6 hours at 110 ºC, as determined by ANP. The kinetic parameters of activation energy (Ea) and pre-exponential factor (A) were determined utilizing the Arrhenius equation, from data obtained in the isothermal thermogravimetric curves.

Due to the intense activity in the textile business Piranhas River, which traverses the city of São Bento-PB is serving as the depletion for the waste generated in the steps of bleaching and dyeing of yarn, since the networks are made by artisans, many them in the backyards of residences. On this context, for this work, we collected water and sediment samples at three different points of the Piranhas, with the objective to evaluate a possible contamination of these compartments resulting from dumping of textile effluent. Were also determined the variables Dissolved Oxygen (DO), Total Dissolved Solids (TDS), OM (Organic Matter), Conductivity, pH and temperature. The results obtained for these parameters are consistent with those expected for the location of the environment under study, where the rainfall is marked by extreme irregularity. An analysis screening using the voltammetry technique was used to indicate the presence of trace metals in water, this analysis showed the possible presence of metals, Zn, Pb and Cu. Concerning the sediment samples, the quantitative analysis performed using the technique of ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) showed that among the investigated metals, Cd, Pb, Cu, Cr, Ni, Cr and Ni elements were those with higher levels during the study period. Using parameters of the sediment quality evaluators, it was observed that the metals Cr and Ni had values that exceeded the lower limit TEL (Canadian guideline value) thus indicating a deleterious made occasional on aquatic biota of the environment under study. Principal components analysis (PCA) using variables such as the physical-chemical parameters and concentrations of metals investigated, highlighted the influence of parameters and STD Conductivity, pH and organic matter in the grouping of data and also showed that the differences in metal contents between months in the study (rainy and dry) were more relevant than the differences between the sampling sites investigated. From the results and taking into account the variables measured along the river, it was found that there is no evidence that the textile wastewater at the moment, is affecting the characteristics of the Piranhas.

Air pollution is of great concern to all of us, and among the main causes are the gases emitted from fossil fuels burning. Therefore, the search for clean technologies is of prime importance nowadays. Thus, in the present work the reaction mechanism for the hydrodesulfurization is investigated. Such reaction is widely used in oil refinery, where new materials, with lowest cost and greater range of application, are searched for. This reaction causes the reduction of hydrocarbons containing sulfur-based functional groups, such as thiols, sulfides and thiophenes, releases hydrogen sulfide, and is catalyzed by molybdenum sulfides or oxides. Since the absorption of SOx compounds is harmful to health and environment, the levels of these types of compounds should be considerably reduced, according to the Kyoto Protocol and the current legislation. In the present study, the hydrodesulfurization reaction involving thiophene is investigated through the use of Quantum Chemical Methods. A mechanism is proposed, using the MoO3, NiMoO4 and CrMoO4 compounds as catalysts. Besides, the effects of Mo6+, Ni2+ and Cr2+ ions are analyzed and also, a mechanism is proposed, considering Thermodynamic and Kinetic Chemistry aspects, once they are not completely established in literature. Geometry optimization and harmonic frequency calculations are performed using the PM6 method, implemented in MOPAC2007. The catalysts structures are built from experimental data provided by the Inorganic Crystal Structure Database. Reaction enthalpies, entropies, Gibbs free energies, as well as activation and reaction energies are computed. Some results of this work comprehend values referring to absortion energies for the catalysts MoO3, MoO3:Ni e MoO3:Cr, corresponding to -117.23, -115.26 and -407.14 kJ mol-1, respectively, originating the following stability order: Cr > Mo > Ni.

This study proposes a modification in the Successive Projections Algorithm (SPA), that makes models of Multiple Linear Regression (MLR) more robust in terms of interference. In SPA, subsets of variables are compared based on their root mean square errors for the validation set. By taking into account the statistical prediction error obtained for the calibration set, and dividing by the statistical prediction error obtained for the prediction set, SPA can be improved. Also taken into account is the leverage associated with each sample. Three case studies involving; simulated analytic determinations, food colorants (UV-VIS spectrometry), and ethanol in gasoline (NIR spectrometry) are discussed. The results were evaluated using the root mean square error for an independent prediction set (Root Mean Square Error of Prediction - RMSEP), graphs of the variables, and the statistical tests t and F. The MLR models obtained by the selection using the new function were called SPE-SPA-MLR. When an interferent was present in the prediction spectra, almost all of the models performed better than both SPA-MLR and PLS. The models when compared to SPA-MLR showed that the change promoted better models in all cases giving smaller RMSEPs and variable numbers. The SPE-SPA-MLR was not better in some cases, than PLS models. The variables selected by SPA-SPE-MLR when observed in the spectra were detected in regions where interference was the at its smallest, revealing great potential. The modifications presented here make a useful tool for the basic formulation of the SPA.

This study proposed a miniaturized flow-batch system for chemical analysis. The technique used microfabricated urethane-acrylate, a commercial polymer. The microsystem was evaluated and optimized by analysis of synthetic dye samples. Afterwards, it was employed for the determination of tannins in tea samples. The tannins are a group of polyphenols of significant relevance in the food industry and pharmaceuticals. The samples used were green and black tea, obtained from the local market. The determinations were performed by turbidimetric methods using copper (II) in an acetate medium, with photometric methods and ferrous tartrate as a reference. Miniaturization in urethane-acrylate implies low cost and low maintenance, rapid prototyping and includes the satisfactory physicochemical properties of polymer. These characteristics combined with the general advantages of miniaturization in analytical devices, such as high frequency analysis and low waste generation, make the system a great source in academic research. For analysis of tannins in tea samples, the system had precise and accurate results, and high speeds. This flow-batch microsystem was able to perform up to 300 tests per hour, for the photometric method of reference and up to 200 tests per hour for the turbidimetric method. Each analysis performed generated waste volumes lower than 70 μL. Data validation of statistical models obtained have proved very satisfactory and promising for new optical applications.

The search for new energy sources and concern about environmental problems has caused an increase in the use of gaseous fuels like natural gas (CNG) and liquefied petroleum gas (LPG). The main advantages of these fuels besides clean energy, are low production and processing costs, high efficiency and versatility. Given these realities, there is both growing need and demand for quality controls applicable to these types of fuel. This study proposes quality screening analysis of gaseous fuels using near infrared (NIR) absorption spectroscopy for verifying adulteration and/or nonconformity of LPG and CNG samples. The development of gas handling equipment made possible the construction of different classification models for screening analysis, such as SIMCA, SPA-SPA-LDA and SIMCA. To build and test these models, several samples were grouped as; tampered with, adulterated, and commercially certified standard. The results demonstrated the methodology as effective and robust for performing preliminary analysis of CNG and LPG quality, minimizing normal drawbacks of the quality control reference methods used for these fuels.