Oxidação úmida de fenóis com catalisadores de ferro suportado em argilominerais em reator de leito de lama (slurry)

The wet oxidation of organic compounds with CO2 and H2O has been demonstrated to be an efficient technique for effluent treatment. This work focuses on the synthesis, characterization and catalytic performance of Fe-MnO2/CeO2, K-MnO2/CeO2/ palygorskite and Fe/ palygorskite toward the wet oxidative degradation of phenol. The experiments were conducted in a sludge bed reactor with controlled temperature, pressure and stirring speed and sampling of the liquid phase. Experiments were performed on the following operating conditions: temperature 130 ° C, pressure 20.4 atm, catalyst mass concentration of 5 g / L initial concentration of phenol and 0.5 g / L. The catalytic tests were performed in a slurry agitated reactor provided with temperature, pressure and agitation control and reactor liquid sampling. The influences of iron loaded on the support (0.3; 7 and 10%, m/m) and the initial pH of the reactant medium (3.1; 6.8; 8.7) were studied. The iron dispersion on the palygorskite, the phase purity and the elemental composition of the catalyst were evaluated by X-Ray Difraction (XRD), Scanning Electron Microscopy (SEM) and X-Ray Flourescence (XRF). The use of palygorskite as support to increase the surface area was confirmed by the B.E.T. surface results. The phenol degradation curves showed that the Fe3+ over palygorskite when compared with the other materials tested has the best performance toward the (Total Organic carbonic) TOC conversion. The decrease in alkalinity of the reaction medium also favors the conversion of TOC. The maximum conversion obtained from the TOC with the catalyst 3% Fe / palygorskite was around 95% for a reaction time of 60 minutes, while reducing the formation of acids, especially acetic acid. With products obtained from wet oxidation of phenol, hydroquinone, p-benzoquinone, catechol and oxalic acid, identified and quantified by High Performance Liquid Chromatography was possible to propose a reaction mechanism of the process where the phenol is transformed into the homogeneous and heterogeneous phase in the other by applying a kinetic model, Langmuir-Hinshelwood type, with evaluation of kinetic constants of different reactions involved.

Motivação para o trabalho: um estudo com os profissionais de saúde das unidades básicas de saúde do município de Natal RN

This thesis studied the motivation to work among health professionals of the Basic Unities (BUH) in the health network of the city of Natal (RN). It was understood that the work motivation is a process. Then, the expectation theory was applied and motivation components (results of work, expectative, valence, instrumentality, and motivational force) were used to analyses. It s understanding the motivation as multifaceted phenomenon, the psycho sociological perspective was adopted. The research was developed in two phases: one with application of Work Motivation and Meaning Inventory (WMMI), and another with interview. In the first phases, the analysis of results revealed that the major factors contributing to increase the motivational force to health professionals in the BUH´s are: in valence, Self Expression and Personal Realization (VF2), Personal and Family Survival (VF3); in expectative, Self Expression and Work Justice (EF1), Safety and Dignity (EF2) and Responsibility (EF4); in instrumentality, Involvement (IF1) and Recognition and Economic Independence (IF4). In opposition, the factors that more contribute to reduce the motivational force are Wear and Dehumanization factors in valence (VF4), in expectative (EF3), and in instrumentality (IF4), behind the Work Justice Factor (IF2). Basing in content analysis of interviews, it was possible to associate by equivalence, the senses presented by health professionals with obtained results of first phase, indicating that the results of second phase corroborated and complemented those of first one. This possibility broadened the comprehension of the studied phenomenon. In speaking of the respondents, it was visible the presence of contents showing that they perceive the Health System and BUH´s in degradation. In the first phase, the participants´ instruction also predict the results in motivation, and in the interviews can be saw that the instruction is associated with the opportunities in outside of system. As work motivation is a process, the impact of personal and occupational characteristics tend to interact with contextual aspects. It was concluded the majority of health professionals present the moderated motivational force, but it was falling because they experience and perceive a degrading context with work condition increasingly unfavorable.

Superparamagnetismo em Jacobsitas sintéticas

In this experimental study sintetic samples of Jacobsites (MnFe2O4) were synthesized by the Pechini method and calcined within ambient atmosphere and afterwards in the vacuum from 400 to 700ºC, the range of calcination temperatures. The X-Ray Diffraction (XRD) and the Scanning Electronic Microscopy (SEM) analysis have shown that the samples treated at 400ºC temperature are composed by a simple type of spinel phase, with a crystallite size of 8:8nm for the sample calcined in ambient atmosphere and 20; 1nm for the sample treated in the vacuum, showing that the cristallite average size can be manipulated by the atmosphere control. The hysteresis loops for the sample calcined at 400ºC in ambient atmosphere reveal features of superparamagnetic behavior with magnetization 29:3emu=g at the maximum field of 1:2T. The sample calcined in 400oC under vacuum show magnetization = 67emu=g at the maximum field of 1:5T. The sample treated at 500oC, under ambient atmosphere, has shown besides the spinel phase, secondary phases of hematite (Fe2O3) and bixbyite (FeMnO3). The hysteresis loops demonstrate a sharp drop of the magnetization compared to the previous sample. The analysis has revealed that for the samples treated in higher temperatures (600ºC and 700ºC) its observed the absence of the spinel phase and the maintenance of the bixbyite and hematite. The hysteresis loops for those samples in accordance to the external magnetic field are straight lines crossing the origin, consistent with the antiferromagnetic behavior of the phases.The Mössbauer espectroscopy show to the sample calcined at 400ºC within ambiente atmosphere two sextet and one doublet. The two sextets are assigned to the hyperfine fields related to the magnetic deployment in the nuclei of Fe3+ ions, at the tetraedric and octaedric sites. The doublet is assigned to superparamagnetic behavior of the particles with smaller diameter than dc . Now the sample calcined at 400ºC under vacuum only show two sextet

Aplicação do Na2S2O8, H2O2 e ferro na remediação de solos (latossolo e areia destrófica) contaminados com diesel

Environmental liabilities from accidents in the retail petroleum industry, especially in urban areas, have represented a serious problem whose impact reaches the underground, people's health and even economic losses with the remediation process. In U.S.A. are estimated hundreds of billions of dollars invested in soil remediation processes. The results of the reports and investigative reports of liabilities in fuel stations distributed in the urban area of Natal-RN were used to estimate the local scenario of contamination. This database has been possible to determine the main contaminants (BTEX, PAHs, TOC), affected neighborhoods and types of potentially more impacted soils. Experiments were carried out in order to reverse contamination of this scenario, where the soil type was a factor in the planning, because it influences directly on the effectiveness of remediation techniques studied: Oxidation by hydrogen peroxide and oxidation by sodium persulphate. These oxidants are activated forming free radicals (HO•-, SO4 •-, HO2 • , O2 •-, S2O8 -2, etc) responsible for to mineralize the hydrocarbons and other organic compounds (releasing O2 e CO2). In the activation process, the ferrous ions (II) and ferric (III) were studied as well as hydrogen peroxide activation technique with sodium persulfate, the latter being presented the best efficiency among all the study, when activated with Fe+3. In addition to defining the most efficient technique, the aim of this study was to evaluate the influence of different soils among oxidative techniques, characterizing the effect of the concentration of these oxidants and also the concentration of the catalysts. Exists in most scenarios evaluated the presence of intrinsic total iron soil matrix. The so-called latosols present microaggregates reddish indicating the presence of these reactive species like iron and clayey aspect. The kinetic study was conducted by experimental design and monitoring of the percentage of total carbon (SSM-5000A) in the solid and liquid phases, knowing that 82.4% of the diesel molecule is carbon. Yet organic carbon and pH of liquid samples were analyzed for technical, characterizing the influence of soil type and its operating condition. The Fenton-like technique H2O2 e Fe+2 presented satisfactory oxidation, including sandy soil, but well below the best result. The sodium persulphate only activated with temperature, even in the most favorable soil, did not provide good efficiency. The best technique in the study had the concentration profile with 2,2x10- 1mol.L-1 of Na2S2O8 activated with 6,53x10-1mol.L-1 of H2O2 and 2,5x10-2 Fe3+mol.L-1 which reduced in less than a day 96 contamination in red soil, initially with 66,667 mg of diesel per kg of clean soil

Estudo de complexos de ferro e de cobre com a base de Shiff 3-Meosalen e ligantes de relevância biológica

The goal set for this work was to synthesize and to characterize new iron and copper complexes with the Schiff base 3-MeOsalen and ligands of biological relevance, whose formulas are [Fe(3-MeOsalen)NO2], [Fe(3-MeOsalen)(etil2-dtc)], [Fe(3-MeOsalen)NO] and Na[Cu(3-MeOsalen)NO2]. The compounds were characterized by vibrational spectroscopy in the infrared region (IV) and Electronic spectroscopy in the ultraviolet and visible region (Uv-Vis). From the analysis of infrared spectra, they proved to formation of precursor complexes, as evidenced by changes in the vibrationals frequencies ν(C=N) e ν(C-O) and the emergence of vibrationals modes metal-oxygen and metal-nitrogen. For nitro complexes of iron and copper were observed ν(NO2)ass around 1300 cm-1 e ν(NO2)sim in 1271 cm-1 , indicating that the coordination is done via the nitrogen atom. The complex spectrum [Fe(3-MeOsalen)(etil2-dtc)] exhibited two bands, the ν(C-NR2) in 1508 cm-1 e ν(C-S) in 997 cm-1 , the relevant vibrational modes of coordinating ligand in the bidentate form. For the complex [Fe(3-MeOsalen)NO] was observed a new intense band in 1670 cm-1 related to the ν(NO). With the electronic spectra, the formation of complexes was evidenced by shifts of bands intraligands transitions and the emergence of new bands such as LMCT (p Cl-  d* Fe3+) in [Fe(3-MeOsalen)Cl] and the d-d in [Cu(3-MeOsalen)H2O]. As for the [Fe(3-MeOsalen)NO2] has highlighted the absence of LMCT band present in the precursor complex as for the [Cu(3-MeOsalen)NO2] found that the displacement of the band hipsocrômico d-d on 28 nm. The electronic spectrum of [Fe(3-MeOsalen)(etil2-dtc)] presented LMCT band shifts and changes in intraligantes transitions. With regard to [Fe(3-MeOsalen)NO], revealed a more energetic transitions intraligands regions from the strong character π receiver NO and MLCT band of transition dπFe(II)π*(NO).

Síntese e caracterizações estrutural e magnética das ferritas de cobalto-manganês (Co1-xMnxFe2O4 E Co1,2Fe1,8-xMnxO4)

The cobalt-manganese ferrites (Co1¡xMnxFe2O4 and Co1,2Fe1,8¡xMnxO4) has a mixed structure of spinel type and it has been regarded as one of candidates for petitive wide variety of applications in devices from ultrasonic generation and detection, sensors, transformers, as well as in medical industry. Ferrites cobalt-manganese nanostructured were produced via mechanical alloying with subsequent heat treatment and were characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy and magnetization. Samples of Co1¡xMnxFe2O4 and Co1,2Fe1,8¡xMnxO4 were obtained from the precursor powders Fe3O4, Co3O4 and Mn3O4 which were stoichiometrically mixed and ground by 10h and heat treated at 900°C for 2h. The diffraction confirmed the formation of the pure nanocrystalline phases to series Co1,2Fe1,8¡xMnxO4 with an average diameter of about 94nm. It was found that the lattice parameter increases with the substitution of Fe3Å by Mn3Å. The x-ray fluorescence revealed that the portions of metals in samples were close to the nominal stoichiometric compositions. The microstructural features observed in micrographs showed that the particles formed show very different morphology and particle size. The magnetic hysteresis measurements performed at low temperature showed that the saturation magnetization and remanence increased as the concentration of manganese, while the coercive field decreased. The anisotropy constant (Ke f ), was estimated from the data adjustments the law of approaching saturation. It was found that the anisotropy decreases substantially with the substitution of Fe by Mn.

Ordenamento de cargas e propriedades magnéticas de ortoferritas de lantânio dopadas com estrôncio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ordenamento de cargas e propriedades magnéticas de ortoferritas de lantânio dopadas com estrôncio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)