Microemulsões aplicadas ao tratamento de Óleos isolantes

Naphthenic lubricating oils are used in transformers with the purpose of promoting electrical insulation and dissipating heat. The working temperature range of these oils typically lies between 60°C and 90°C and their useful life is 40 years in average. In that temperature range, the oils are decomposed during operation, whereby a small fraction of polar compounds are formed. The presence of these compounds may induce failure and loss of physical, chemical and electrical properties of the oil, thus impairing the transformer operation. By removing these contaminants, one allows the oxidized insulating oil to be reused without damaging the equipment. In view of this, an investigation on the use of surfactants and microemulsions as extracting agents, and modified diatomite as adsorbent, has been proprosed in this work aiming to remove polar substances detected in oxidized transformer oils. The extraction was carried out by a simple-contact technique at room temperature. The system under examination was stirred for about 10 minutes, after which it was allowed to settle at 25°C until complete phase separation. In another experimental approach, adsorption equilibrium data were obtained by using a batch system operating at temperatures of 60, 80 and 100°C. Analytical techniques involving determination of the Total Acidity Number (TAN) and infrared spectrophotometry have been employed when monitoring the decomposition and recovery processes of the oils. The acquired results indicated that the microemulsion extraction system comprising Triton® X114 as surfactant proved to be more effective in removing polar compounds, with a decrease in TAN index from 0.19 to 0.01 mg KOH/g, which is consistent with the limits established for new transformer oils (maximal TAN = 0.03 mg KOH/g). In the adsorption studies, the best adsorption capacity values were as high as 0.1606 meq.g/g during conventional adsoprtion procedures using natural bauxite, and as high as 0.016 meq.g/g for the system diatomite/Tensiofix® 8426. Comparatively in this case, a negative effect could be observed on the adsorption phenomenon due to microemulsion impregnation on the surface of the diatomite

Análises Estruturais e atividades biológicas de exopolissacarídeo extraído do fungo comestível pleurotus Sajor-Caju e de seu derivado sulfatado quimicamente.

The exopolysaccharides are extracellular compounds produced by some species of fungi and bacteria. It is suggested that these molecules, even when in the form of complex polysaccharide-peptide, are the main bioactive molecules of many fungus. Some of the biological activities displayed by these compounds can be accentuated and others may arise when you add chemically polar or nonpolar groups to polysaccharides. The fruiting body of Pleurotus sajor-caju produces a heteropolysaccharide with antineoplastic and antimicrobial activity, but other biological activities of this polymer have not been evaluated. In this work the exopolysaccharide of Pleurotus sajor-caju was sulfated chemically and structurally characterized. We also evaluated the antiproliferative, antioxidant and anticoagulant activities from native exopolysaccharide (PN) and its sulfated derivated (PS). Polyacrylamide gel electrophoresis, infrared spectroscopy and nuclear magnetic resonance (¹³C) proved successful in sulfation of PN to obtain PS. Analysis by gas chromatography-mass spectroscopy showed that PN and PS are composed of mannose, galactose, 3-O-methyl-galactose and glucose in proportion percentage of 44,9:16,3:19,8:19 and 49, 7:14,4:17,7:18,2, respectively. The percentage of sulfate found in PS was 22.5%. Antioxidants assays revealed that the sulfation procedure affects differently the activities of exopolysaccharides, while the total antioxidant capacity, the scavenging activity of superoxide radical and ferric chelating were not affected by sulfation, on the other hand the chemical modification of PN enhanced the scavenging activity of hydroxyl radical and reducing power. PS also showed anticoagulant activity in a dose-dependent manner and clotting time was 3.0 times higher than the baseline value in APTT at 2 mg/mL. The exopolysaccharide not presented antiproliferative activity against HeLa tumor cells, but PS affects the cellular proliferation in a time-dependent manner. After 72 h, the inhibition rate of PS (2.0 mg/mL) on HeLa cells was about 60%. The results showed that PN sulfation increase some of their activities.

Preparação e caracterização de catalisadores à base de titânio suportado em MCM-41 para produção de compostos oxigenados através da pirólise catalítica do capim elefante

In recent years, the area of advanced materials has been considerably, especially when it comes to materials for industrial use, such as is the case with structured porosity of catalysts suitable for catalytic processes. The use of catalysts combined with the fast pyrolysis process is an alternative to the oxygenate production of high added value, because, in addition to increasing the yield and quality of products, allows you to manipulate the selectivity to a product of interest, and therefore allows greater control over the characteristics of the final product. Based on these arguments, in this work were prepared titanium catalysts supported on MCM-41 for use in catalytic pyrolysis of biomass, called elephant grass. The reactions of pyrolysis of biomass were performed in a micro pyrolyzer, Py-5200, coupled to GC / MS, the company CDS Corporation, headquartered in the United States. The catalysts Ti-MCM-41 in different molar ratios were characterized by XRD, TG / DTG, FT-IR, SEM, XRF, UV-visible adsorption of nitrogen and the distribution of particle diameter and specific surface area measurement by the BET method. From the catalytic tests it was observed that the catalysts synthesized showed good results for the pyrolysis reaction.The main products were obtained a higher yield of aldehydes, ketones and furan. It was observed that the best reactivity is a direct function of the ratio Si/Ti, nature and concentration of the active species on mesoporous supports. Among the catalysts Ti-MCM-41 (molar ratio Si / Ti = 25 and 50), the ratio Si / Ti = 25 (400 ° C and 600 ° C) favored the cracking of oxygenates such as acids , aldehydes, ketones, furans and esters. Already the sample ratio Si / Ti = 50 had the highest yield of aromatic oxygenates

Desenvolvimento de pastas cimentantes utilizando cimentos portland compostos para cimentação de poços petrolíferos

The Compound Portland cements are commonly used in construction, among them stand out the CPII-Z, CPII-F and CPIV. These types of cement have limited application on oil well cementing, having its compositional characteristics focused specifically to construction, as cement for use in oil wells has greater complexity and properties covering the specific needs for each well to be coated. For operations of oil wells cementing are used Portland cements designed specifically for this purpose. The American Petroleum Institute (API) classifies cements into classes designated by letters A to J. In the petroleum industry, often it is used Class G cement, which is cement that meets all requirements needed for cement from classes A to E. According to the scenario described above, this paper aims to present a credible alternative to apply the compound cements in the oil industry due to the large availability of this cement in relation to oil well cements. The cements were micro structurally characterized by XRF, XRD and SEM tests, both in its anhydrous and hydrated state. Later technological tests were conducted to determine the limits set by the NBR 9831. Among the compound cements studied, the CPII-Z showed satisfactory properties for use in primary and secondary operations of oil wells up to 1200 meters cementing

Design gráfico da pluma de contaminação por compostos orgânicos voláteiss utilizando software CAD na investigação de passivo ambiental em um posto revendedor de combustíveis em Natal/RN

Among the potentially polluting economic activities that compromise the quality of groundwater are the gas stations. The city of Natal has about 120 gas stations, of which only has an environmental license for operation. Discontinuities in the offices were notified by the Public Ministry of Rio Grande do Norte to carry out the environmental adaptations, among which is the investigation of environmental liabilities. The preliminary and confirmatory stages of this investigation consisted in the evaluation of soil gas surveys with two confirmatory chemical analysis of BTEX, PAH and TPH. To get a good evaluation and interpretation of results obtained in the field, it became necessary three-dimensional representation of them. We used a CAD software to graph the equipment installed in a retail service station fuel in Natal, as well as the plumes of contamination by volatile organic compounds. The tool was concluded that contamination is not located in the current system of underground storage of fuel development, but reflects the historical past in which tanks were removed not tight gasoline and diesel

Estudo da remoção de compostos orgânicos, benzeno e tolueno, em solução aquosa por processo oxidativo avançado do tipo Fenton

The oil and petrochemical industry is responsable to generate a large amount of waste and wastewater. Among some efluents, is possible find the benzene, toluene, ethilbenze and isomers of xilenes compounds, known as BTEX. These compounds are very volatily, toxic for environment and potencially cancerigenous in man. Oxidative advanced processes, OAP, are unconventional waste treatment, wich may be apply on treatment and remotion this compounds. Fenton is a type of OAPs, wich uses the Fenton s reactant, hydrogen peroxide and ferrous salt, to promove the organic degradation. While the Photo-Fenton type uses the Fenton s reactant plus UV radiation (ultraviolet). These two types of OAP, according to literature, may be apply on BTEX complex system. This project consists on the consideration of the utilization of technologies Fenton and Photo-Fenton in aqueous solution in concentration of 100 ppm of BTEX, each, on simulation of condition near of petrochemical effluents. Different reactors were used for each type of OAP. For the analyticals results of amount of remotion were used the SPME technique (solid phase microextraction) for extraction in gaseous phase of these analytes and the gas chromatography/mass espectrometry The arrangement mechanical of Photo-Fenton system has been shown big loss by volatilization of these compounds. The Fenton system has been shown capable of degradate benzene and toluene compounds, with massic percentage of remotion near the 99%.

Estudo da influência de compostos recalcitrantes na remoção de matéria orgânica biodegradável no tratamento de efluente de refinarias de petróleo

Petroleum Refinery wastewaters (PRW) have hart-to-degrade compounds, such as: phenols, ammonia, cyanides, sulfides, oils and greases and the mono and polynuclear aromatic hydrocarbons: benzene, toluene and xylene (BTX), acenaphthene, nitrobenzene and naphtalene. It is known that the microrganisms activity can be reduced in the presence of certain substances, adversely affecting the biological process of wastewater treatment. This research was instigated due the small number of studies regarding to this specific topic in the avaiable literature. This body of work ims to evaluate the effect of toxic substances on the biodegradability of the organic material found in PRW. Glucose was chosen as the model substrate due to its biodegradable nature. This study was divided into three parts: i) a survey of recalcitants compounds and the removal of phenol by using both biological and photochemical-biological processes; ii) biomass aclimation and iii) evaluation of the inhibitory effect certain compounds have on glucose biodegradation. The phenol degradation experiments were carried out in an activity sludge system and in a photochemical reactor. The results showed the photochemical-biological process to be more effective on phenol degradation, suggesting the superioruty of a combined photochemical-biological treatment when compared with a simple biological process for phenol removal from industry wastewaters. For the acclimation step, was used an activated sludge from industrial wastewaters. A rapid biomass aclimation to a synthetic solution composed of the main inhibitory compouns fpund in a PRW was obtained using the following operation condition: (pH = 7,0; DO ≥ 2,0 mg/L; RS = 20 days e qH = 31,2 and 20,4 hours), The last part was consisted of using respirometry evaluation toxicity effects of selected compounds over oxygen uptake rate to adaptated and non adaptated biomass in the presence of inhibitory compounds. The adaptated sludge showed greater degration capacity, with lower sensibility to toxic effects. The respirometry has proved to be very practical, as the techiniques used were simple and rapid, such as: Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), and Volatile Suspended Solids (VSS). Using the latter it is possible to perform sludge selection to beggingthe process; thus allowing its use for aerobic treatment system`s behacior prediction

Utilização de uma coluna de flotação para remoção de compostos orgânicos da água de produção

Innovative technologies using surfactant materials have applicability in several industrial fields, including petroleum and gas areas. This study seeks to investigate the use of a surfactant derived from coconut oil (SCO saponified coconut oil) in the recovery process of organic compounds that are present in oily effluents from petroleum industry. For this end, experiments were accomplished in a column of small dimension objectifying to verify the influence of the surfactant SCO in the efficiency of oil removal. This way, they were prepared emulsions with amount it fastens of oil (50, 100, 200 and 400 ppm), being determined the great concentrations of surfactant for each one of them. Some rehearsals were still accomplished with produced water of the industry of the petroleum to compare the result with the one of the emulsions. According to the experiments, it was verified that an increase of the surfactant concentration does not implicate in a greater oil removal. The separation process use gaseous bubbles formed when a gas stream pass a liquid column, when low surfactant concentrations are used, it occurs the coalescence of the dispersed oil droplets and their transport to the top of the column, forming a new continuous phase. Such surfactants lead to a gas-liquid interface saturation, depending on the used surfactant concentration, affecting the flotation process and influencing in the removal capacity of the oily dispersed phase. A porous plate filter, with pore size varying from 40 to 250 mm, was placed at the base of the column to allow a hydrodynamic stable operation. During the experimental procedures, the operating volume of phase liquid was held constant and the rate of air flow varied in each experiment. The resulting experimental of the study hydrodynamic demonstrated what the capturing of the oil was influenced by diameter of the bubbles and air flow. With the increase flow of 300 about to 900 cm3.min-1, occurred an increase in the removal of oil phase of 44% about to 66% and the removal kinetic of oil was defined as a reaction of 1° order

Concepção e estudo de um biofiltro para tratamento de compostos orgânicos voláteis COVs

In the last decade, biological purification of gaseous waste has become an important alternative to many conventional methods of exhaust air treatment. More recently, biofiltration has proved to be an effective and inexpensive method for the treatment of air contaminated with volatile organic compounds (VOCs). A biofilter consists in a reactor packed with a porous solid bed material, where the microorganisms are fixed. During the biofiltration process, polluted air is transported through the biofilter medium where the contaminant is degraded. Within the biofilm, the pollutants in the waste gases are energy and carbon sources for microbial metabolism and are transformed into CO2, water and biomass. The bed material should be characterized by satisfactory mechanical and physical properties as structure, void fraction, specific area and flow resistance. The aim of this research was the biofilter construction and study of the biological degradation of ethanol and toluene, as well as the modeling of the process. Luffa cylindrica is a brazilian fiber that was used as the filtering material of the present work. The parameters and conditions studied were: composition of nutrients solution; effect of microflorae strains, namely Pseudomanas putida and Rhodococcus rhodochrous; waste gas composition; air flow rate; and inlet load of VOCs. The biofilter operated in diffusion regime and the best results for remotion capacity were obtained when a microorganisms consortion of Pseudomanas putida and Rhodococcus rhodochrous,were used, with a gas flow rate of 1 m3.h-1 and molar ratio nitrogene/phosphore N/P=2 in the nutrients solution. The maximum remotion capacity for ethanol was around 90 g.m-3.h-1 and 50 g.m-3.h-1 to toluene. It was proved that toluene has inhibitory effect on the ethanol remotion When the two VOCs were present in the same waste gas, there was a decrease of 40% in ethanol remotion capacity. Luffa cylindrica does not present considerable pressure drop. Ottengraf and van Lith models were used to represent the results obtained for ethanol and toluene, respectively. The application of the transient model indicated a satisfactory approximation between the experimental results obtained for ethanol and toluene vapors biofiltration and the ones predicted it

Propriedades física de molécilas orgânicas e compostos do tipo perovskita CdSiO3 e CaPbO3

In the first part of this work our concern was to investigate the thermal effects in organic crystals using the theory of the polarons. To analyse such effect, we used the Fröhlich s Hamiltonian, that describes the dynamics of the polarons, using a treatment based on the quantum mechanics, to elucidate the electron-phonon interaction. Many are the forms to analyzing the polaronic phenomenon. However, the measure of the dielectric function can supply important information about the small polarons hopping process. Besides, the dielectric function measures the answer to an applied external electric field, and it is an important tool for the understanding of the many-body effects in the normal state of a polaronic system. We calculate the dielectric function and its dependence on temperature using the Hartree-Fock decoupling method. The dieletric function s dependence on the temperature is depicted by through a 3D graph. We also analyzed the so called Arrhenius resistivity, as a functionof the temperature, which is an important tool to characterize the conductivity of an organic molecule. In the second part we analyzed two perovskita type crystalline oxides, namely the cadmium silicate triclinic (CdSiO3) and the calcium plumbate orthorhombic (CaPbO3), respectively. These materials are normally denominated ABO3 and they have been especially investigated for displaying ferroelectric, piezoelectric, dielectrics, semiconductors and superconductors properties. We found our results through ab initio method within the functional density theory (DFT) in the GGA-PBE and LDA-CAPZ approximations. After the geometry optimization for the two structure using the in two approximations, we found the structure parameters and compared them with the experimental data. We still determined further the angles of connection for the two analyzed cases. Soon after the convergence of the energy, we determined their band structures, fundamental information to characterize the nature of the material, as well as their dielectrics functions, optical absorption, partial density of states and effective masses of electrons and holes

Estudo de propriedades elétricas em compostos de Bario

Este trabalho tem como objetivo estudar a influência da adição de diversos aditivos tais como óxido de silício (SiO2), óxido de bismuto (BiO2), óxido de cério (CeO2) e óxido de lantânio (La2O3) nas propriedades elétricas e dielétricas do titanato de bário (BaTiO3) policristalino. As amostras de titanato de bário foram compactadas e sinterizadas no Laboratório de Tecnologia dos Pós, do Departamento de Física da Universidade Federal do Rio Grande do Norte. Foram realizadas medidas de resistividade elétrica e constante dielétrica em função da temperatura, bem como ensaios de difração de raios-X e análise microestrutural através da microscopia eletrônica de varredura. A análise dos resultados permitiu avaliar a influência dos aditivos nas propriedades elétricas e dielétricas, e propor a utilização de cerâmicas eletrônicas a base de titanato de bário com propriedades superiores as do material existente atualmente

Degradação de compostos orgânicos voláteis usando o catalisador SBA-15 contendo titânio

The groundwater pollution arising due to fuel leaks gas stations has presented a problem aggravating. Increasingly studies related to environmental problems such accidents and seek to propose some solutions for the treatment of groundwater and soils that are contaminated by gasoline. This study evaluated the use of molecular sieve TiSBA-15 as a catalyst for the reaction of removing of volatile organic compounds, particularly benzene, toluene, ethylbenzene and xylenes, known as BTEX, one of the main pollutants found in groundwater. The catalyst was synthesized by the method post-synthesis techniques and characterized by XSD, TG/DTG, adsorption/desorption of N2, XRF-EDX, for checking the incorporation of titanium and formation of the structure of the catalyst. The reaction occurred with the presence of hydrogen peroxide, H2O2, in aqueous medium to form hydroxyl radicals, which are needed in the process of removal of BTEX compounds. The catalytic reaction was carried out for 5 hours at 60 °C, pH to 3.0, and analyzes of the compounds were made in a gas chromatograph with a flame detection means photoionization static headspace (HS-GC-PID). The catalytic tests have shown the efficacy of using this type of catalyst for the removal of these volatile organic compounds, having a removal rate of 90.60% in the range where the catalyst was studied TiSBA-15(5,0)

Estudo teórico QTAIM e DFT dos compostos de coordenação: efeito quelato, titanocenos e ligação química

This work is a study of coordination compounds by quantum theory of atoms in molecules (QTAIM), based on the topological analysis of the electron density of molecular systems, both theoretically and experimentally obtained. The coordination chemistry topics which were studied are the chelate effect, bent titanocene and chemical bond in coordination complexes. The chelate effect was investigated according to topological and thermodynamic parameters. The exchange of monodentate ligands on polydentate ligands from same transition metal increases the stability of the complex both from entropy and enthalpy contributions. In some cases, the latter had a higher contribution to the stability of the complex in comparison with entropy. This enthalpic contribution is explained according to topological analysis of the M-ligand bonds where polidentate complex had higher values of electron density of bond critical point, Laplacian of electron density of bond critical point and delocalization index (number of shared electrons between two atoms). In the second chapter, was studied bent titanocenes with bulky cyclopentadienyl derivative π-ligand. The topological study showed the presence of secondary interactions between the atoms of π-ligands or between atoms of π-ligand and -ligand. It was found that, in the case of titanocenes with small difference in point group symmetry and with bulky ligands, there was an nearly linear relationship between stability and delocalization index involving the ring carbon atoms (Cp) and the titanium. However, the titanocene stability is not only related to the interaction between Ti and C atoms of Cp ring, but secondary interactions also play important role on the stability of voluminous titanocenes. The third chapter deals with the chemical bond in coordination compounds by means of QTAIM. The quantum theory of atoms in molecules so far classifies bonds and chemical interactions in two categories: closed shell interaction (ionic bond, hydrogen bond, van der Waals interaction, etc) and shared interaction (covalent bond). Based on topological parameters such as electron density, Laplacian of electron density, delocalization index, among others, was classified the chemical bond in coordination compounds as an intermediate between closed shell and shared interactions

Utilização de uma coluna de flotação para remoção de compostos orgânicos da água de produção

Innovative technologies using surfactant materials have applicability in several industrial fields, including petroleum and gas areas. This study seeks to investigate the use of a surfactant derived from coconut oil (SCO saponified coconut oil) in the recovery process of organic compounds that are present in oily effluents from petroleum industry. For this end, experiments were accomplished in a column of small dimension objectifying to verify the influence of the surfactant SCO in the efficiency of oil removal. This way, they were prepared emulsions with amount it fastens of oil (50, 100, 200 and 400 ppm), being determined the great concentrations of surfactant for each one of them. Some rehearsals were still accomplished with produced water of the industry of the petroleum to compare the result with the one of the emulsions. According to the experiments, it was verified that an increase of the surfactant concentration does not implicate in a greater oil removal. The separation process use gaseous bubbles formed when a gas stream pass a liquid column, when low surfactant concentrations are used, it occurs the coalescence of the dispersed oil droplets and their transport to the top of the column, forming a new continuous phase. Such surfactants lead to a gas-liquid interface saturation, depending on the used surfactant concentration, affecting the flotation process and influencing in the removal capacity of the oily dispersed phase. A porous plate filter, with pore size varying from 40 to 250 mm, was placed at the base of the column to allow a hydrodynamic stable operation. During the experimental procedures, the operating volume of phase liquid was held constant and the rate of air flow varied in each experiment. The resulting experimental of the study hydrodynamic demonstrated what the capturing of the oil was influenced by diameter of the bubbles and air flow. With the increase flow of 300 about to 900 cm3.min-1, occurred an increase in the removal of oil phase of 44% about to 66% and the removal kinetic of oil was defined as a reaction of 1° order.

Síntese e caracterização de compostos de coordenação homolépticos e heterolépticos com o ligante ácido kójico

The present work has as main objective to contribute to the coordination chemistry of the ligand kojic acid, with the synthesis and characterization of the homoleptic compounds [Al(kj)3], [Fe(kj)3], [Fe(kj)2], [Cu(kj)2] e [Ru(kj)3], and the new heteroleptic complexes, trans- K2[Fe(kj)2(CN)2] and trans-Na2[Ru(kj)2(CN)2]. The obtained compounds were characterized by vibrational spectroscopy in the infrared region (IV) and Electronic spectroscopy in the ultraviolet and visible region (Uv-Vis). The infrared results indicated the coordination of the bidentate ligand kojic acid, due to reductions in the values of the stretching frequencies of the carbonyl and double bonds, compared to the free ligand for all complexes obtained. The presence of new vibrational modes indicated the change of symmetry of the molecules in the new compounds synthesized. Additionally, the presence of vibrational modes assigned to metal-oxygen also contributed to confirm the ligand coordinating to the metal ions. Through this technique, was also possible to perform correlations of the numbers of vibrational modes, in the region 1400-900 cm-1 and the compounds geometry. The heteroleptic compounds exhibited υC≡N in 2065 and 2053 cm-1, respectively, for the trans-K2[Fe(kj)2(CN)2] and trans-Na2[Ru(kj)2(CN)2], indicating coordination of the cyano ligand to metal ions FeII e RuII. Comparing the obtained values with literature data was possible to identify the complex isomerism as trans. In relation to the results of electronic spectroscopy, studies of pH variation of kojic acid provided information on the distribution of electron density in the molecule, showing characteristic spectral profile of kojic ion and its protonated form (Hkj, kojic acid), with two bands at 215 and 269 nm, or deprotonated (kj-), with bands at 226 and 315 nm. The electronic spectra obtained for all complexes in aqueous medium, in the ultraviolet region, exhibited variations of the energies assigned to kojic acid intraligand transitions while in the visible region, only transitions assigned to charge transfer of iron and ruthenium complex have been identified