Síntese de catalisadores nanoporosos na ausência total e parcial de direcionadores orgânicos para pirólise catalítica de óleos pesados e intermediários

The processing of heavy oil produced in Brazil is an emergency action and a strategic plan to obtain self-sufficiency and economic surpluses. Seen in these terms, it is indispensable to invest in research to obtain new catalysts for obtaining light fraction of hydrocarbons from heavy fractions of petroleum. This dissertation for the degree of Doctor of Philosophy reports the materials preparation that combine the high catalytic activity of zeolites with the greater accessibility of the mesoporosity, more particularly the HZSM-5/MCM-41 hybrid, done by synthesis processes with less environmental impact than conventional ones. Innovative methodologies were developed for the synthesis of micro-mesoporous hybrid material by dual templating mechanism and from crystalline zeolitic aluminosilicate in the absence of organic template. The synthesis of hybrid with pore bimodal distribution took place from one-single organic directing agent aimed to eliminate the use of organic templates, acids of any kind or organic solvents like templating agent of crystalline zeolitic aluminosilicate together with temperature-programmed microwave-assisted, making the experimental procedures of preparation most practical and easy, with good reproducibility and low cost. The study about crystalline zeolitic aluminosilicate in the absence of organic template, especially MFI type, is based on use of H2O and Na+ cation playing a structural directing role in place of an organic template. Advanced characterization techniques such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Highresolution Transmission Electron Microscopy (HRTEM), Adsorption of N2 and CO2, kinetic studies by Thermogravimetric Analysis (TGA) and Pyrolysis coupled to Gas Chromatography/Mass Spectrometry (Pyrolysis-GC/MS) were employed in order to evaluate the synthesized materials. Achieve the proposed objectives, has made available a set of new methodologies for the synthesis of zeolite and hybrid micro-mesoporous material, these suitable for catalytic pyrolysis of heavy oils aimed at producing light fraction

Reciclagem química de Polietileno utilizando Sílica Mesoporosa tipo SBA-15 avalizada por Termogravimetriae Espectrometria de Massas

The chemical recycling of polyolefins has been the focus of increasing attention owing potential application as a fuel and as source chemicals. The use of plastic waste contributes to the solution of pollution problems.The use of catalysts can enhance the thermal degradation of synthetic polymers, which may be avaliated by Themogravimetry (TG) and mass spectrometry (MS) combined techniques. This work aims to propose alternatives to the chemistry recycling of low-density polyethylene (LDPE) on mesoporous silica type SBA-15 and AlSBA-15.The mesoporous materials type SBA-15 and AlSBA-15 were synthesized through the hydrothermal method starting from TEOS, pseudobohemite, cloridric acid HCl and water. As structure template was used Pluronic P123. The syntheses were accomplished during the period of three days. The best calcination conditions for removal of the organic template (P123) were optimized by thermal analysis (TG/DTG) and through analyses of Xray diffraction (XRD), infrared spectroscopy (FT-IR), nitrogen adsorption and scanning electron microscopy (SEM) was verified that as much the hydrothermal synthesis method as the calcination by TG were promising for the production of mesoporous materials with high degree of hexagonal ordination. The general analysis of the method of Analog Scan was performed at 10oC/min to 500 oC to avoid deterioration of capillary with very high temperatures. Thus, with the results, we observed signs mass/charge more evident and, using the MID method, was obtained curve of evolution of these signals. The addition of catalysis produced a decrease in temperature of polymer degradation proportional to the acidity of the catalyst. The results showed that the mesoporous materials contributed to the formation of compounds of lower molecular weight and higher value in the process of catalytic degradation of LDPE, representing an alternative to chemical recycling of solid waste

Avaliação da remoção catalítica de compostos orgânicos monoaromáticos em água utilizando materiais nanoestruturados de sílica

Statistics of environmental protection agencies show that the soil has been contaminated with problems often resulting from leaks, spills and accidents during exploration, refining, transportation and storage oil operations and its derivatives. These, gasoline noteworthy, verified by releasing, to get in touch with the groundwater, the compounds BTEX (benzene, toluene, ethylbenzene and xylenes), substances which are central nervous system depressants and causing leukemia. Among the processes used in remediation of soil and groundwater contaminated with organic pollutants, we highlight those that use hydrogen peroxide because they are characterized by the rapid generation of chemical species of high oxidation power, especially the hydroxyl radical ( OH), superoxide (O2 -) and peridroxil (HO2 ), among other reactive species that are capable of transforming or decomposing organic chemicals. The pH has a strong effect on the chemistry of hydrogen peroxide because the formation of different radicals directly depends on the pH of the medium. In this work, the materials MCM-41 and Co-MCM-41 were synthesized and used in the reaction of BTEX removal in aqueous media using H2O2. These materials were synthesized by the hydrothermal method and the techniques used to characterize were: XRD, TG/DTG, adsorption/desorption N2, TEM and X-Ray Fluorescence. The catalytic tests were for 5 h of reaction were carried out in reactors of 20 mL, which was accompanied by the decomposition of hydrogen peroxide by molecular absorption spectrophotometry in the UV-Vis, in addition to removal of organic compounds BTEX was performed as gas chromatography with detection photoionization and flame ionization and by static headspace sampler. The characterizations proved that the materials were successfully synthesized. The catalytic tests showed satisfactory results, and the reactions containing BTEX + Co-MCM-41 + H2O2 at pH = 12.0 had the highest percentages of removal for the compounds studied

Interações entre a carboximetilcelulose, carbonato de cálcio e bentonita: repercussões sobre as propriedades dos fluidos de perfuração aquosos

The role of carboxymethylcellulose (CMC) in association to calcium carbonate particles (CaCO3) in most water-based drilling fluids is to reduce the fluid loss to the surrounding formation. Another essential function is to provide rheological properties capable of maintaining in suspension the cuttings during drilling operation. Therefore, it is absolutely essential to correlate the polymer chemical structure (degree of substitution, molecular weight and distribution of substituent) with the physical-chemical properties of CaCO3, in order to obtain the better result at lower cost. Another important aspect refers to the clay hydration inhibitive properties of carboxymethylcellulose (CMC) in drilling fluids systems. The clay swelling promotes an undesirable damage that reduces the formation permeability and causes serious problems during the drilling operation. In this context, this thesis consists of two main parts. The first part refers to understanding of interactions CMC-CaCO3, as well as the corresponding effects on the fluid properties. The second part is related to understanding of mechanisms by which CMC adsorption occurs onto the clay surface, where, certainly, polymer chemical structure, ionic strength, molecular weight and its solvency in the medium are responsible to affect intrinsically the clay layers stabilization. Three samples of carboximetilcellulose with different molecular weight and degree of substitution (CMC A (9 x 104 gmol DS 0.7), CMC B (2.5 x 105 gmol DS 0.7) e CMC C (2.5 x 105 gmol DS 1.2)) and three samples of calcite with different average particle diameter and particle size distribution were used. The increase of CMC degree of substitution contributed to increase of polymer charge density and therefore, reduced its stability in brine, promoting the aggregation with the increase of filtrate volume. On the other hand, the increase of molecular weight promoted an increase of rheological properties with reduction of filtrate volume. Both effects are directly associated to hydrodynamic volume of polymer molecule in the medium. The granulometry of CaCO3 particles influenced not only the rheological properties, due to adsorption of polymers, but also the filtration properties. It was observed that the lower filtrate volume was obtained by using a CaCO3 sample of a low average size particle with wide dispersion in size. With regards to inhibition of clay swelling, the CMC performance was compared to other products often used (sodium chloride (NaCl), potassium chloride (KCl) and quaternary amine-based commercial inhibitor). The low molecular weight CMC (9 x 104 g/mol) showed slightly lower swelling degree compared to the high molecular weight (2.5 x 105 g/mol) along to 180 minutes. In parallel, it can be visualized by Scanning Electron Microscopy (SEM) that the high molecular weight CMC (2.5 x 105 g/mol e DS 0.7) promoted a reduction in pores formation and size of clay compared to low molecular weight CMC (9.0 x 104 g/mol e DS 0.7), after 1000 minutes in aqueous medium. This behavior was attributed to dynamic of interactions between clay and the hydrodynamic volume of CMC along the time, which is result of strong contribution of electrostatic interactions and hydrogen bounds between carboxylate groups and hydroxyls located along the polymer backbone and ionic and polar groups of clay surface. CMC adsorbs on clay surface promoting the skin formation , which is responsible to minimize the migration of water to porous medium. With the increase of degree of substitution, it was observed an increase of pores onto clay, suggesting that the higher charge density on polymer is responsible to decrease its flexibility and adsorption onto clay surface. The joint evaluation of these results indicate that high molecular weight is responsible to better results on control of rheological, filtration and clay swelling properties, however, the contrary effect is observed with the increase of degree of substitution. On its turn, the calcite presents better results of rheological and filtration properties with the decrease of average viii particle diameter and increase of particle size distribution. According to all properties evaluated, it has been obvious the interaction of CMC with the minerals (CaCO3 and clay) in the aqueous medium

Desenvolvimento de catalisadores bifuncionais de óxido de zircônio modificado por óxidos de tungstênio e molibdênio contendo platina para a reação de isomerização de n-parafinas

Bifunctional catalysts based on zircon oxide modified by tungsten (W = 10, 15 and 20 %) and by molybdenum oxide (Mo= 10, 15 e 20 %) containg platinum (Pt = 1%) were prepared by the polymeric precursor method. For comparison, catalysts the tungsten base was also prepared by the impregnation method. After calcinations at 600, 700 and 800 ºC, the catalysts were characterized by X-ray diffraction, fourier-transform infrared spectroscopy, thermogravimetric and differential thermal analysis, nitrogen adsorption and scanning electron microscopy. The profile of metals reduction was determined by temperature programmed reduction. The synthesized catalysts were tested in n-heptane isomerization. X-ray diffractogram of the Pt/WOx-ZrO2 and Pt/MoOx-ZrO2 catalysts revealed the presence of tetragonal ZrO2 and platinum metallic phases in all calcined samples. Diffraction peaks due WO3 and ZrO2 monoclinic also were observed in some samples of the Pt/WOx-ZrO2 catalysts. In the Pt/MoOx-ZrO2 catalysts also were observed diffraction peaks due ZrO2 monoclinic and Zr(MoO4)2 oxide. These phases contained on Pt/WOx-ZrO2 and Pt/MoOx-ZrO2 catalysts varied in accordance with the W or Mo loading and in accordance with the calcination temperature. The infrared spectra showed absorption bands due O-W-O and W=O bonds in the Pt/WOx-ZrO2 catalysts and due O-Mo-O, Mo=O and Mo-O bonds in the Pt/MoOx-ZrO2 catalysts. Specific surface area for Pt/WOx-ZrO2 catalysts varied from 30-160 m2 g-1 and for the Pt/MoOx-ZrO2 catalysts varied from 10-120 m2 g-1. The metals loading (W or Mo) and the calcination temperature influence directly in the specific surface area of the samples. The reduction profile of Pt/WOx-ZrO2 catalysts showed two peaks at lower temperatures, which are attributed to platinum reduction. The reduction of WOx species was evidenced by two reduction peak at high temperatures. In the case of Pt/MoOx-ZrO2 catalysts, the reduction profile showed three reduction events, which are attributed to reduction of MoOx species deposited on the support and in some samples one of the peak is related to the reduction of Zr(MoO4)2 oxide. Pt/WOx-ZrO2 catalysts were active in the n-heptane isomerization with high selectivity to 3-methyl-hexane, 2,3- dimethyl-pentane, 2-methyl-hexane among other branched hydrocarbons. The Pt/MoOx-ZrO2 catalysts practically didn't present activity for the n-heptane isomerization, generating mainly products originating from the catalytic cracking

Desenvolvimento de sistema magnético polimérico contendo antimicrobianos para tratamento de infecções por Helicobacter pylori

Helicobacter pylori is the main cause of gastritis, gastroduodenal ulcer disease and gastric cancer. The most recommended treatment for eradication of this bacteria often leads to side effects and patient poor compliance, which induce treatment failure. Magnetic drug targeting is a very efficient method that overcomes these drawbacks through association of the drug with a magnetic compound. Such approach may allow such systems to be placed slowed down to a specific target area by an external magnetic field. This work reports a study of the synthesis and characterization of polymeric magnetic particles loaded with the currently used antimicrobial agents for the treatment of Helicobacter pylori infections, aiming the production of magnetic drug delivery system by oral route. Optical microscopy, scanning electron microscopy, transmission electron microscopy, x-ray powder diffraction, nitrogen adsorption/desorption isotherms and vibrating sample magnetometry revealed that the magnetite particles, produced by the co-precipitation method, consisted of a large number of aggregated nanometer-size crystallites (about 6 nm), creating superparamagnetic micrometer with high magnetic susceptibility particles with an average diameter of 6.8 ± 0.2 μm. Also, the polymeric magnetic particles produced by spray drying had a core-shell structure based on magnetite microparticles, amoxicillin and clarithromycin and coated with Eudragit® S100. The system presented an average diameter of 14.2 ± 0.2 μm. The amount of magnetite present in the system may be tailored by suitably controlling the suspension used to feed the spray dryer. In the present work it was 2.9% (w/w). The magnetic system produced may prove to be very promising for eradication of Helicobacter pylori infections

Modelagem Matemática e Computacional de fenômenos eletrocinéticos em meios porosos carregados eletricamente

In this work we present a mathematical and computational modeling of electrokinetic phenomena in electrically charged porous medium. We consider the porous medium composed of three different scales (nanoscopic, microscopic and macroscopic). On the microscopic scale the domain is composed by a porous matrix and a solid phase. The pores are filled with an aqueous phase consisting of ionic solutes fully diluted, and the solid matrix consists of electrically charged particles. Initially we present the mathematical model that governs the electrical double layer in order to quantify the electric potential, electric charge density, ion adsorption and chemical adsorption in nanoscopic scale. Then, we derive the microscopic model, where the adsorption of ions due to the electric double layer and the reactions of protonation/ deprotanaç~ao and zeta potential obtained in modeling nanoscopic arise in microscopic scale through interface conditions in the problem of Stokes and Nerst-Planck equations respectively governing the movement of the aqueous solution and transport of ions. We developed the process of upscaling the problem nano/microscopic using the homogenization technique of periodic structures by deducing the macroscopic model with their respectives cell problems for effective parameters of the macroscopic equations. Considering a clayey porous medium consisting of kaolinite clay plates distributed parallel, we rewrite the macroscopic model in a one-dimensional version. Finally, using a sequential algorithm, we discretize the macroscopic model via the finite element method, along with the interactive method of Picard for the nonlinear terms. Numerical simulations on transient regime with variable pH in one-dimensional case are obtained, aiming computational modeling of the electroremediation process of clay soils contaminated

Evolução termocronológica do sistema de falhas Senador Pompeu-CE

The region of the Senador Pompeu Shear Zone (SPSZ), in the North Tectonic Domain of the Borborema Province (BP), has its recent history associated with to South Atlantic Ocean formation event at the Jurassic. A lot of geologics models have discussed about crustal axis elevation in local scale and large scale (Borborema Province), relative to importants regionals tectonics directions of it. The identification and the relationship among this surfaces, stepped in many topographyc levels by tectonics mecanisms, is dificult because of the erosion process on it. Over there, sedimentary deposits is complex and it has not biostratigraphyc record in continental deposits. The analysis metodology on apatita fission-track, in the region of the SPSZ, purpose the more knowledge about morphotectonics mecanisms of the area and the impruvement of its morphotectonics models. For this, it was moleled the age and thermal history of the 11 apatites samples collected on both sides of this shear zone, taking relationships among other results of the thermochronology studies in the BP. Based on the thermal studies in this search, the region of the BP developed on two distint cooling events, separated for one period of relative stabilited. The first episode occur between 130 and 90 M.y., has been began when the samples cross the 120°C isoterm for last time and fineshed at 70°C. The second moment of the cooling process was began about 30 M.y., when the temperature was 90°C, from this to the equlibrium with present surface temperature at 30°C. Some evidences indicated a relacionship between thermal episodes and uplift events of the regional relief. The fundaments of the interpretation was based mainly on comparatives studies among results of the thermochronology analysis and geologics studies about BP. Nóbrega et al.(2005), e.g., on studies about the Portalegre Shear Zone, got similar results on SPSZ, with some details relative to local tectonic activity. Morais Neto et al. (2000) interpreted two importants cooling events in the BP based on their regional studies, that can be associated to regional uplift events. When Assine (1992) studied the stratigraphyc sequences of the Araripe Basin, in the south of Ceará state, conclude that the abrupt return to continentals condictions from the last sedimentar sequency (albiano-cenomaniane) indicate a regional uplift of the NE region of the Brazil at the 100 M.y., in the Albiano Intermediate/Superior. This ages are compatible to termal model of the SPSZ. This two periods of the thermal history of the BP are completely registered in the apatites samples just one age groups of the fission-track, that it is the most ancient age groups. This one suggest it has happened in response to heating before 75 M.y and it has erased the last report of the first moment relief evolution of the BP. The NNE-SSW and E-W structure reativation can have created ideal condictions for heating and local elevations of the geothermal gradients. The equilibrium between the apatites temperatures of this groups and the regionais temperatures took place about 50 M.y., when the samples of the two ages groups had a simillar evolution to present surfaces temperatures

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

Qualidade do solo da camada de cobertura final em área de disposição de resíduos no semiárido tropical

The final disposal of municipal solid waste in unsuitable areas without an infrastructure that meets the health measures and environmental protection, coupled with the lack of technical criteria in phase and decommissioning of the dump can promote environmental degradation. Alternatively to minimize the impacts of this activity for the stabilization of the area by isolating the massive waste with implementation of an adequate and finished by a layer of soil for plant growth final cover system. In this context, the present study aimed to evaluate the quality of the final cover in the area of a disabled dump the tropical semi-arid region in order to assist the process of recovery of these areas. The study area is located in the tropical semi-arid region in São João do Sabugi /RN. Soil samples were collected in the dump area and bushland as a benchmark of quality. To which they were subjected to analysis of physical attributes (particle density, bulk density, grain size and porosity), chemical properties (pH, K + , Na+ , Ca2 + , Mg2 + and Al3 + exchangeable, potential acidity, available phosphorus, sum of bases, CEC, base saturation, aluminum saturation, saturation Na + and adsorption ratio sodium, total organic carbon and total nitrogen) and total and soluble concentrations of heavy metals (Mn, Pb, Zn, Cd, Cu, Mo, Co, Cr, Ba and Ni). The differences between physical and chemical soil under native forest and final cover showing reduction of soil quality in the area off to the dump, which hinders the development of native vegetation and the recovery of the area. The absence of superior waterproofing to allow vertical transfer between the solid waste and the final cover promoted enrichment by chemical elements and heavy metals in excess can impair revegetation. Deficiencies found in the construction process of the final cover point to the need for intervention to accelerate the process of stabilization and recovery of the area of the local ecosystem

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 materiais mesoporosos para a captura de CO2: influência do óxido de níquel

Several materials are currently under study for the CO2 capture process, like the metal oxides and mixed metal oxides, zeolites, carbonaceous materials, metal-organic frameworks (MOF's) organosilica and modified silica surfaces. In this work, evaluated the adsorption capacity of CO2 in mesoporous materials of different structures, such as MCM-48 and SBA- 15 without impregnating and impregnated with nickel in the proportions 5 %, 10 % and 20 % (m/m), known as 5Ni-MCM-48, 10Ni-MCM-48, 20Ni-MCM-48 and 5Ni-SBA-15, 10NiSBA-15, 20Ni-SBA-15. The materials were characterized by means of X-ray diffraction (XRD), thermal analysis (TG and DTG), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption and desorption (BET) and scanning electron microscopy (SEM) with EDS. The adsorption process was performed varying the pressure of 100 - 4000 kPa and keeping the temperature constant and equal to 298 K. At a pressure of 100 kPa, higher concentrations of adsorption occurred for the materials 5Ni-MCM-48 (0.795 mmol g-1 ) and SBA-15 (0.914 mmol g-1 ) is not impregnated, and at a pressure of 4000 kPa for MCM-48 materials (14.89 mmol g-1) and SBA-15 (9.97 mmol g-1) not impregnated. The results showed that the adsorption capacity varies positively with the specific area, however, has a direct dependency on the type and geometry of the porous structure of channels. The data were fitted using the Langmuir and Freundlich models and were evaluated thermodynamic parameters Gibbs free energy and entropy of the adsorption system

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.

Síntese e imobilização de nanopartículas de ouro em fibras regeneradas via exaustão para potencial aplicação biomédica

The advancement of nanotechnology in the synthesis and characterisation of nanoparticles (NP's) has played an important role in the development of new technologies for various applications of nano-scale materials that have unique properties. The scientific development in the last decades in the field of nanotechnology has sought ceaselessly, the discovery of new materials for the most diverse applications, such as biomedical areas, chemical, optical, mechanical and textiles. The high bactericidal efficiency of metallic nanoparticles (Au and Ag), among other metals is well known, due to its ability to act in the DNA of fungi, viruses and bacteria, interrupting the process of cellular respiration, making them important means of study, in addition to its ability to protect UVA and UVB. The present work has as its main objective the implementation of an innovative method in the impregnation of nanoparticles of gold in textile substrate, functionalized with chitosan, by a dyeing process by exhaustion, with the control of temperature, time and velocity, thus obtaining microbial characteristics and UV protection. The exhausted substrates with colloidal solutions of NPAu's presented the colours, lilac and red (soybean knits) due to their surface plasmon peak around 520-540 nm. The NPAu's were synthesized chemically, using sodium citrate as a reducing agent and stabilizer. The material was previously cationised with chitosan, a natural polyelectrolyte, with the purpose of functionalising it to enhance the adsorption of colloid, at concentrations of 5, 7, 10 and 20 % of the bonding agent on the weight of the material (OWM). It was also observed, through an experimental design 23 , with 3 central points, which was the best process of exhaustion of the substrates, using the following factors: Time (min.), temperature (OC) and concentration of the colloid (%), having as a response to variable K/S (ABSORBÂNCIA/ Kubelka-Munk) of the fibres. Furthermore, it was evidenced as the best response, the following parameters: concentration 100%, temperature 70 ºC and time 30 minutes. The substrate with NPAu was characterised by XRD; thermal analysis using TGA; microstructural study using SEM/EDS and STEM, thus showing the NP on the surface of the substrate confirming the presence of the metal. The substrates showed higher washing fastness, antibacterial properties and UV radiation protection.