Fluidos de perfuração aquosos: a contribuição da goma xantana e carboximetilcelulose no controle de filtrado

This study aimed mainly to evaluate the influence of xanthan gum (XG) and carboxymethylcellulose (CMC) in the filtration process of water-based drilling fluids, considering the conformational changes suffered by the polyelectrolyte with the addition of sodium chloride (NaCl) in different concentrations (0.17, 0.34 and 0.51 mol.L-1). It was also evaluated the behavior of the fluid by the addition of calcium carbonate (CaCO3) in pure water and in brine. Seeking a better understanding of the interaction between the polymers used and CaCO3, polymer adsorption analyzes were performed using a depletion method, which yielded a higher percentage of adsorption of Xanthan Gum in this material (29%), which can justify the formation of a thin and waterproof filter cake for drilling fluids containing this polymer. However, the best values of apparent viscosity (20 and 24 mPa.s) and volume of filtrate (8.0 and 8.1 mL) were obtained for the systems consisting of xanthan gum, CMC and CaCO3, in NaCl aqueous solutions concentrations of 0.34 and 0.51 mol.L-1, respectively. The values can be related to the presence of CMC that increases the apparent viscosity and reduces the volume of filtrate. In addition, the CaCO3 added acts as a bridging agent, promoting the formation of a less permeable filter cake

Desenvolvimento de pastas cimentantes contendo nanossílica como material estendedor para aplicação em fases iniciais, de poços petrolíferos, submetidas à baixa temperatura (5°c ± 3ºc)

The improved performance of hydraulic binders, the base of Portland cement, consists in the careful selection and application of materials that promote greater durability and reduced maintenance costs There is a wide variety of chemical additives used in Portland cement slurries for cementing oil wells. These are designed to work in temperatures below 0 ° C (frozen areas of land) to 300 ° C (thermal recovery wells and geothermal); pressure ranges near ambient pressure (in shallow wells) to greater than 200 MPa (in deep wells). Thus, additives make possible the adaptation of the cement slurries for application under various conditions. Among the materials used in Portland cement slurry, for oil wells, the materials with nanometer scale have been applied with good results. The nanossílica, formed by a dispersion of SiO2 particles, in the nanometer scale, when used in cement systems improves the plastic characteristics and mechanical properties of the hardened material. This dispersion is used commercially as filler material, modifier of rheological properties and / or in recovery processes construction. It is also used in many product formulations such as paints, plastics, synthetic rubbers, adhesives, sealants and insulating materials Based on the above, this study aims to evaluate the performance of nanossílica as extender additive and improver of the performance of cement slurries subjected to low temperatures (5 ° C ± 3 ° C) for application to early stages of marine oil wells. Cement slurries were formulated, with densities 11.0;12.0 and 13.0 ppg, and concentrations of 0; 0.5, 1.0 and 1.5%. The cement slurries were subjected to cold temperatures (5 ° C ± 3 ° C), and its evaluation performed by tests rheological stability, free water and compressive strength in accordance with the procedures set by API SPEC 10A. Thermal characterization tests (TG / DTA) and crystallographic (XRD) were also performed. The use of nanossílica promoted reduction of 30% of the volume of free water and increased compression resistance value of 54.2% with respect to the default cement slurry. Therefore, nanossílica presented as a promising material for use in cement slurries used in the early stages of low-temperature oil wells

Obtenção e caracterização de complexos polieletrolíticos de quitosana e poli (metacrilato de sódio)

Polyelectrolyte complexes (PECs) nanoparticles were prepared using chitosan and sodium polymethacrylate. The complex formation was investigated using turbidimetry, conductometry, viscometry, and dynamic light scattering. The presence of excess positive charges was evidenced by zeta potential measurements. The particle diameter was characterized by dynamic light scattering and the morphology by atomic force microscopy. In all experiments an abrupt change in behavior was observed at a carboxyl:amino molar ratio around 0.7−0.8. Those changes in behavior were related to a proposed mechanism of complex formation based on the decrease of macromolecular dimensions of soluble polyelectrolyte complex clusters, followed by phase segregation

Determinação da concentração de metais no material particulado (PM10 e PM2,5) do ar atmosférico em uma área urbana da cidade do Natal – RN

This study aimed to assess ambient air quality in a urban area of Natal, capital of Rio Grande do Norte (latitude 5º49'29 '' S and longitude 35º13'34'' W), aiming to determine the metals concentration in particulate matter (PM10 and PM2,5) of atmospheric air in the urban area o the Natal city. The sampling period for the study consisted of data acquisition from January to December 2012. Samples were collected on glass fiber filters by means of two large volumes samplers, one for PM2,5 (AGV PM 2,5) and another for PM10 (PM10 AGV). Monthly averages ranged from 8.92 to 19.80 g.m-3 , where the annual average was 16,21 g.m-3 for PM10 and PM2,5 monthly averages ranged from 2,84 to 7,89 g.m -3 , with an annual average of 5,61 g.m-3 . The results of PM2,5 and PM10 concentrations were related meteorological variables and for information on the effects of these variables on the concentration of PM, an exploratory analysis of the data using Principal Component Analysis (PCA) was performed. The results of the PCA showed that with increasing barometric pressure, the direction of the winds, the rainfall and relative humidity decreases the concentration of PM and the variable weekday little influence compared the meteorological variables. Filters containing particulate matter were selected in six days and subjected to microwave digestion. After digestion samples were analyzed by with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The concentrations for heavy metals Vanadium, Chromium, Manganese, Nickel, Copper, Arsenic and lead were determined. The highest concentrations of metals were for Pb and Cu, whose average PM10 values were, respectively, 5,34 and 2,34 ng.m-3 and PM2,5 4,68 and 2,95 ng.m-3 . Concentrations for metals V, Cr, Mn, Ni, and Cd were respectively 0,13, 0,39, 0,48, 0,45 and 0,03 ng.m-3 for PM10 fraction and PM2,5 fraction, 0,05, 0,10, 0,10, 0,34 and 0,01 ng.m-3. The concentration for As was null for the two fractions

Determinação da energia de ativação e pureza de medicamentos de referência, genérico e similar utilizando técnicas termoanalíticas

In this work, the reference drugs, generic and similar to the active ingredients acetylsalicylic acid, paracetamol, captopril, hydrochlorothiazide and mebendazole were purchased from local pharmacies and studied by thermogravimetry (TG) and Differential Scanning Calorimetry (DSC). Thermal decomposition was assessed to obtain from the Ozawa method the activation energy in inert atmosphere (nitrogen), using three different heating ratios (5, 10 and 20 o C min-1). The pharmaceutical formulation of the AAS reference was the one who presented different from the others (generic and similar) Thermogravimetric profile indicating likely interaction between the active ingredient and excipients. Was observed at the heating rate of the inverse temperature that no linearity of the data, ie, there was no correlation between the percentage of mass loss and the activation energy involved in the thermal decomposition of the pharmaceutical formulation of the AAS reference log graph. The analysis by differential scanning calorimetry was performed in nitrogen atmosphere with a heating rate of 10 ° C min-1. In the analysis of these same drugs, the data curves found on the melting point were, except for hydrochlorothiazide, are consistent with the literature. Hydrochlorothiazide presented a melting point well below that found in the literature, which may be justified due to the interaction of the active ingredient with the excipient lactose. In the study of purity, using the Van't Hoff equation, the reference drugs hydrochlorothiazide and mebendazole reference generic and showed similar impurity content below the limit established that this equation must be greater than 2.5 mol%

Caracterização físico-química de sistemas micelares

The process of adsorption and micellization of the surfactants sodium dodecyl sulfate, dodecylammonium chloride and hexaethylene glycol mono-n-dodecyl ether in water-air interface has been studied using measurements of surface tension in aqueous media and NaCl 0.1 mol/L in temperatures of 25, 33 and 40 °C. From these data, critical micelle concentrations and thermodynamic parameters of micellization and adsorption were determined in order to elucidate the behaviors of micellization and adsorption for these surfactants in the proposed medium. For the determination of the thermodynamic parameters of adsorption we utilized the equations of isotherms of Langmuir and Gibbs. Γmáx values determined by the different equations were correlated to the explanation of results. Temperature and salinity were analyzed in terms of their influence on the micellization and adsorption process, and the results were explained based on intermolecular interactions. The values of Gmic have confirmed that the micelle formation for the surfactants studied occurs spontaneously

Síntese e caracterização de complexo tetranuclear de cobre com o ligante resorcinareno

The main objective of the present work is to contribute to the development of the coordination chemistry of macromolecules such as resorcinarene with the synthesis and characterization of new copper complexes with chloride, vanillin and resorcinarene binders, all coordinated to phenanthroline, a biologically active molecule with important properties in biological systems. The complex [(Cu(phen))4(resvan)], was synthesized from the direct reaction of the metals with resorcinarene and generates several possibilities for coordination, which hinders its characterization. Therefore, in order to limit the coordination sites of the ligand, the complex [(Cu(phen))4(resvan)]Cl4 was formed from a new synthetic methodology. The complex cis-[Cu(phen)Cl2], cis-[Cu(phen)(van)]Cl, [(Cu(phen))4(resvan)] and [(Cu(phen))4(resvan)]Cl4 were characterized by spectroscopic techniques such as IR, UV-vis and EPR. By using infrared it has been possible to demonstrate the presence of the phenanthroline ligand in the synthesized complexes, and vanillin in the complex cis- [Cu(phen)(van)]Cl and resvan ligand in the complex [(Cu(phen))4(resvan)], besides this indicating the formation of resorcinarene in the complex [(Cu(phen))4(resvan)]Cl4. The electronic spectra of these coordination compounds indicated the presence of the phenanthroline ligand, by its intense bands in the ultraviolet region. For the complex cis- [Cu(phen)(van)]Cl it still indicated the presence of the ligand vanillin based on intraligand bands of vanillin and charge transfer, LMCT. Furthermore, the spectra showed d-d bands, confirming the formation of metal compounds. The amount of copper atoms present in the complex [(Cu(phen))4(resvan)]Cl4 was estimated from a comparative analysis of the absorbances of solutions of the same concentration of [(Cu(phen))4(resvan)]Cl4 and cis- [Cu(phen)(van)]Cl, which indicates that these compounds have copper atoms in the ratio 4:1. The EPR spectra of the complex cis-[Cu(phen)Cl2], cis-[Cu(phen)(van)]Cl and [(Cu(phen))4(resvan)]Cl4 showed axial profiles, while the complex [(Cu(phen))4(resvan)] showed of axial and rhombic profiles, indicating a change in the symmetry of the Cu (II) to this complex environment. The binders vanillin and resvan underwent biological assays with satisfactory results, both exhibited antioxidant activity and low toxicity, as well vanillin present antitoxoplásmico character.

Possibilidades de enfoque CTS para o ensino superior de química: proposta de uma abordagem para ácidos e bases

Scientific education has been passing by redefinitions, contestations and new contributions from the research on science teaching. One contribution is the idea of science and technology literacy, allowing the citizens not only knowing science but also understand aspects on the construction and motivation of scientific and technological research. In accordance with this idea, there is the Science-Technology-Society (STS) studies which, since the 1970s, has been contributing for science teaching and learning according to the comprehension of the relationships with society in the Western countries of the North. In Brazil, this approach began to gain projection from the 1990s when the first essays on the theme were published. Currently, there is a clear influence of this approach on the national curriculum guidelines, especially for the area of Natural Sciences, and also on the textbooks chosen by the High School National Program (Programa Nacional do Ensino Médio). However, there seems to be a gap in relation to the discussion on the specific curricular component seen in college on this approach. Thus, this study aims at adopting the approach STS, face to the preparation of complimentary educational material on acid and bases concepts studied in the course of General Chemistry of the Natural Sciences graduation program. To this end, it was performed a bibliographical research aiming at making the state-of-the-art in in these concepts in specific literature to science teaching. It is divided in two stages: systematic study (with sixteen journals chosen according to Qualis-Capes and an unsystematic study with direct search in databases and references in the papers of the systematic study. The studies had their content analyzed and the categories chosen a priori were the level of education, the acid-base theory adopted, and the strategy/theoretical frame of reference adopted. A second stage aimed at identifying attitudes and beliefs on STS (Science-Technology-Society) and CSE (Chemistry-Society-Environment) of students in the teacher and technologist training course in three diferent institutions: UTFPR, UFRN and IFRN. In this study, it was used two questionnaires, composed of a Likert scale, semantic differential scale and open questions. The quantitative data reliability was estimated through Cronbach’s alpha method, and tha data were treated according to classic statistics, using the mean as the centrality measures, and the mean deviation as dispersion. The qualitative data were treated according to the content analysis with categories taken from the reading of answers. In the third stage, it was analyzed the presence of STS and CSE content in chapters on acid and bases concepts of nine General Chemistry textbooks, frequently used in graduation programs in public institutions of the state of Rio Grande do Norte. The results showed that there are few proposals of acid and bases teaching, and they are generally aimed at High School or at instrumentation for teaching courses, and no course for General Chemistry. The student’s attitudes and beliefs show the presence of a positivist point of view based on the concept of Science and Technology neutrality and the salvation of its mediation. The books analysis showed just a few content on STS and CSE are found in the studied chapters, and they are generally presented disjointedly in relation to the rest of the main text. In the end, as suggestion to solve the absence of proposals STS in General Chemistry books, as well as the student’s positivist attitudes, it was developed some educational material to be used in the course of General Chemistry at College. The material is structured to introduce a historical view of the concepts preparation, present the use of materials, the industrial and technological processes, and social and environmental consequences of this activities

Estudo teórico de intermediários tetraédricos acidez / basicidade e estereosseletividade enzimáticos

The present work aimed first, the theoretical study of tetrahedral intermediate stability formed from carbonyl addition reactions using the second (MP2) and third (MP3) order Møller–Plesset perturbation theory. Linear correlations between electronic energy difference of reactions with Wiberg Indexes and C-O bond lengths were obtained, and was observed that the stability of adducts formed depends directly of electronic density involved between these atoms. The knowing of electronic parameters of these structures has an important hole due to the large use on reactions that in his course forms this tetrahedral intermediate. Employing the ONIOM (B3LYP:AMBER) methodology, was evaluated the stereoselectivity of a enzymatic reaction between CAL B enzyme and a long chain ester. In this study, were obtained the electronic energies of ground state and intermediate state of transesterification rate-determing step from two possible proquirals faces Re and Si. The objective was study the enantioselectivity of CAL B and rationalizes it using quantum theory of atoms in molecules (QTAIM). A theoretical study employing inorganic compounds was performed using ab initio CBS-QB3 method aiming to find a link between thermodynamic and equilibrium involving acids and bases. The results observed showed an excellent relationship between difference in Gibbs free energy, ΔG of acid dissociation reaction and ΔG of hydrolysis reaction of the corresponding conjugate base. It was also observed, a relationship between ΔG of hydrolysis reaction of conjugate acids and their corresponding atomic radius showing that stability plays an important role in hydrolysis reactions. The importance of solvation in acid/base behavior when compared to theoretical and experimental ΔG´s also was evaluated.

Aproveitamento sustentável do bagaço de cana de açúcar para obtenção do acetato de celulose

The sustainable use of waste resulting from the agribusiness is currently the focus of research, especially the sugar cane bagasse (BCA), being the lignocellulosic waste produced in greater volume in the Brazilian agribusiness, where the residual biomass has been applied in production energy and bioproducts. In this paper, pulp was produced in high purity from the (BCA) by pulping soda / anthraquinone and subsequent conversion to cellulose acetate. Commercial cellulose Avicel was used for comparison. The obtained cellulose acetate was homogeneous acetylation reaction by modifying the variables, the reaction time in hours (8, 12, 16, 20 and 24) and temperature in ° C (25 and 50). FTIR spectra showed characteristic bands identical to cellulosic materials, demonstrating the efficiency of separation by pulping. The characterization of cellulose acetate was obtained and by infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG / DTG / DSC), scanning electron microscopy (SEM) and determining the degree of substitution (DS ) for the cellulose acetate to confirm the acetylation. The optimal reaction time for obtaining diacetates and triacetates, at both temperatures were 20 and 24 h. Cellulose acetate produced BCA presented GS between 2.57 and 2.7 at 25 ° C and 50 ° C GS obtained were 2.66 and 2.84, indicating the actual conversion of cellulose BCA of di- and triacetates. Comparative mode, commercial cellulose Avicel GS showed 2.78 and 2.76 at 25 ° C and 2.77 to 2.75 at 50 ° C. Data were collected in time of 20 h and 24 h, respectively. The best result was for the synthesis of cellulose acetate obtained from the BCA GS 2.84 to 50 ° C and 24 hours, being classified as cellulose triacetate, which showed superior result to that produced with the commercial ethyl cellulose Avicel, demonstrating converting potential of cellulose derived from a lignocellulosic residue (BCA), low cost, prospects of commercial use of cellulose acetate

Avaliação de compatibilidade entre pasta de cimento e fluido de perfuração não-aquoso utilizados em poços petrolíferos

Compatibility testing between a drilling fluid and a cement slurry is one of the steps before an operation of cementing oil wells. This test allows us to evaluate the main effects that contamination of these two fluids may cause the technological properties of a cement paste. The interactions between cement paste and drilling fluid, because its different chemical compositions, may affect the cement hydration reactions, damaging the cementing operation. Thus, we carried out the study of the compatibility of non-aqueous drilling fluid and a cement slurry additives. The preparation procedures of the non-aqueous drilling fluid, the cement paste and completion of compatibility testing were performed as set out by the oil industry standards. In the compatibility test is evaluated rheological properties, thickening time, stability and compressive strength of cement pastes. We also conducted analyzes of scanning electron microscopy and X-ray diffraction of the mixture obtained by the compatibility test to determine the microstructural changes in cement pastes. The compatibility test showed no visual changes in the properties of the cement paste, as phase separation. However, after the addition of nonaqueous drilling fluid to cement slurry there was an increased amount of plastic viscosity, the yield point and gel strength. Among the major causative factors can include: chemical reaction of the components present in the non-aqueous drilling fluid as the primary emulsifier, wetting agent and paraffin oil, with the chemical constituents of the cement. There was a reduction in the compressive strength of the cement paste after mixing with this drilling fluid. Thickening test showed that the oil wetting agent and high salinity of the non-aqueous fluid have accelerating action of the handle of the cement paste time. The stability of the cement paste is impaired to the extent that there is increased contamination of the cement slurry with the nonaqueous fluid. The X-ray diffraction identified the formation of portlandite and calcium silicate in contaminated samples. The scanning electron microscopy confirmed the development of the identified structures in the X-ray diffraction and also found the presence of wells in the cured cement paste. The latter, formed by the emulsion stability of the drilling fluid in the cement paste, corroborate the reduction of mechanical strength. The oil wetting agent component of the non-aqueous drilling fluid, the modified cement hydration processes, mainly affecting the setting time.

Determinação de CD, PB, e TL em água produzida por HR-CS GF AAS após extração em ponto nuvem

Produced water is a major problem associated with the crude oil extraction activity. The monitoring of the levels of metals in the waste is constant and requires the use of sensitive analytical techniques. However, the determination of trace elements can often require a pre-concentration step. The objective of this study was to develop a simple and rapid analytical method for the extraction and pre-concentration based on extraction phenomenon cloud point for the determination of Cd, Pb and Tl in produced water samples by spectrometry of high resolution Absorption source continues and atomization graphite furnace. The Box Behnken design was used to obtain the optimal condition of extraction of analytes. The factors were evaluated: concentration of complexing agent (o,o-dietilditilfosfato ammonium, DDTP), the concentration of hydrochloric acid and concentration of surfactant (Triton X -114). The optimal condition obtained through extraction was: 0,6% m v-1 DDTP, HCl 0,3 mol L-1 and 0,2% m v-1 of Triton X - 114 for Pb; 0,7% m v-1 DDTP, HCl 0,8 mol L-1 and 0,2% m v-1 Triton X-114 for Cd. For Tl was evidenced that best extraction condition occurs with no DDTP, the extraction conditions were HCl 1,0 mol L-1 e 1,0% m v-1 de Triton X - 114. The limits of detection for the proposed method were 0,005 µg L-1 , 0,03 µg L-1 and 0,09 µg L-1 to Cd, Pb and Tl, Respectively. Enrichment factors Were greater than 10 times. The method was applied to the water produced in the Potiguar basin, and addition and recovery tests were performed, and values were between 81% and 120%. The precision was expressed with relative standard deviation (RSD) is less than 5%

Estudo da capacidade de remoção de óleo solúvel, em águas produzidas, por bentonitas hidrofobizadas

In this study we evaluated the capacity removal of PAHs in an oily solution between the bentonite hydrofobized with linseed oil and paraffin with natural bentonite. Analyses of natural bentonite and hydrofobized were made by the characterization techniques: (1) Thermogravimetric Analysis (TGA), which aimed to evaluate the thermal events due to mass loss, both associated with the exit of moisture and decomposition of clay as due to hidrofobizante loss agent. (2) Analysis of X-ray diffraction (XRD) in order to determine the mineralogical phases that make up the structure of clay and (3) Spectrophotometry in the infrared region used to characterize the functional groups of both the matrix mineral (bentonite) and the hidrofobizantes agents (linseed oil and paraffin). We used a factorial design 24 with the following factors; hidrofobizante, percent hidrofobizante, adsorption time and volume of the oily solution. Analyzing the factorial design 24 was seen that none of the factors apparently was more important than the others and, as all responses showed significant values in relation to the ability of oil removal was not possible to evaluate a difference in the degree of efficiency the two hidrofobizantes. For the new study compared the efficiency of the modified clay, with each hidrofobizante separately in relation to their natural form. As such, there are four new factorial designs 23 using natural bentonite as a differentiating factor. The factors used were bentonite (with and without hydrophobization), exposure time of the adsorbent material to the oily solution and volume of an oily solution, trying to interpret how these factors could influence the process of purifying water contaminated with PAHs. Was employed as a technique for obtaining responses to fluorescence spectroscopy, as already known from literature that PAHs, for presenting combined chains due to condensation of the aromatic rings fluoresce quite similar when excited in the ultraviolet region and as an auxiliary technique to gas chromatography / mass spectrometry (GC-MS) used for the analysis of PAHs in order to complement the study of fluorescence spectroscopy, since the spectroscopic method only allows you an idea of total number of fluorescent species contained in the oil soluble. The result shows an excellent adsorption of PAHs and other fluorescent species assigned to the main effect of the first factor, hydrophobization for the first planning 23 BNTL 5%, for 93% the sixth stop in the second test (+-+),factorial design 23 BNTL 10%, the fourth test (++-) with 94.5% the third factorial design 23 BNTP 5%, the second test (+--) with 91% and the fourth and final planning 23 BNTP 10%, the last test ( + + +) with 88%. Compared with adsorption of bentonite in its natural form. This work also shows the maximum adsorption of each hidrofobizante

Características estruturais e fotocatalíticas do compósito oxihidróxido de nióbio/vermiculita

The preparation of nanostructured materials using natural clays as support, has been studied in literature under the same are found in nature and consequently, have a low price. Generally, clays serve as supports for metal oxides by increasing the number of active sites present on the surface and can be applied for various purposes such as adsorption, catalysis and photocatalysis. Some of the materials that are currently highlighted are niobium compounds, in particular, its oxides, by its characteristics such as high acidity, rigidity, water insolubility, oxidative and photocatalytic properties. In this scenario, the study aimed preparing a composite material oxyhydroxide niobium (NbO2OH) / sodium vermiculite clay and evaluate its effectiveness with respect to the natural clay (V0) and NbO2OH. The composite was prepared by precipitation-deposition method and then characterized by X-ray diffraction, infrared spectroscopy (XRD), energy dispersive X-ray (EDS), thermal analysis (TG/DTG), scanning electron microscopy (SEM), N2 adsorption-desorption and investigation of distribution of load. The application of the material NbO2OH/V0 was divided in two steps: first through oxidation and adsorption methods, and second through photocatalytic activity using solar irradiation. Studies of adsorption, oxidation and photocatalytic oxidation monitored the percentage of color removal from the dye methylene blue (MB) by UV-Vis spectroscopy. The XRD showed a decrease in reflection d (001) clay after modification; the FTIR indicated the presence of both the clay when the oxyhydroxide niobium to present bands in 1003 cm-1 related to Si-O stretching bands and 800 cm-1 to the Nb-O stretching. The presence of niobium was also confirmed by EDS indicated that 17 % by mass amount of the metal. Thermal analysis showed thermal stability of the composite at 217 °C and micrographs showed that there was a decrease in particle size. The investigation of the surface charge of NbO2OH/V0 found that the material exhibits a heterogeneous surface with average low and high negative charges. Adsorption tests showed that the composite NbO2OH/V0 higher adsorption capacity to remove 56 % of AM, while the material removed from V0 only 13 % showed no NbO2OH and adsorptive capacity due to the formation of H-aggregates. The percent removal of dye color for the oxidation tests showed little difference from the adsorption, being 18 and 66 % removal of dye color for V0 and NbO2OH/V0 respectively. The NbO2OH/V0 material shows excellent photocatalytic activity managing to remove just 95,5 % in 180 minutes of the color of MB compared to 41,4 % and 82,2 % of V0 the NbO2OH, proving the formation of a new composite with distinct properties of its precursors.

Estudo da incorporação de resíduos de perfuração para aplicação em cimentação de poços de petróleo

During the drilling of oil and natural gas are generated solid waste, liquid and gaseous. These solid fragments, which are known as cuttings, are carried to the surface through the drilling fluid. Furthermore, this fluid serves to cool the bit, keeping the internal pressure of the well, and others. This solid residue is very polluting, because it has incorporated beyond the drilling fluid, which has several chemical additives harmful to the environment, some heavy metals that are harmful to the environment, such as lead. To minimize the residue generated, are currently being studied numerous techniques to mitigate the problems that such waste can cause to the environment, like addition of cuttings in the composition of soil cement brick masonry construction, addition of cuttings on the clay matrix for the manufacture of solid masonry bricks and ceramic blocks and coprocessing of the cuttings in cement. So, the main objective of this work is the incorporation of cuttings drilling of oil wells, the cement slurry used in the cementing operation of the well. This cuttings used in this study, arising from the formation Pendências, was milled and separated in a sieve of 100 mesh. After grinding had a mean particle sike in order of 86 mm and crystal structure containing phases of quartz and calcite type, characteristic of the Portland cement. Were formulated and prepared slurries of cement with density 13 lb / gal, containing different concentrations of gravel, and realized characterization tests API SPEC 10A and RP 10B. Free water tests showed values lower than 5.9% and the rheological model that best described the behavior of the mixtures was the power. The results of compressive strength (10.3 MPa) and stability (Dr <0.5 lb / gal) had values within the set of operational procedures. Thus, the gravel from the drilling operation, may be used as binders in addition to Portland cement oil wells, in order to reuse this waste and reduce the cost of the cement paste.