Navegando por Assunto "Poluentes"

Agora exibindo 1 - 7 de 7

Acesso aberto (Open Access)
Avaliação da poluição por flúor em solos e plantas das redondezas da fábrica de alumínio Albrás, Barcarena-Pa
(Universidade Federal do Pará, 1995-10-31) BENVENUTI, Sara Maria Pinotti; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
The aluminum industry is considered one of the main sources of industrial contamination by fluoride, which generates atmospheric pollution. In this research, a quantitative assessment of the distribution of fluoride in the various environmental compartments in the area of influence of the ALBRÁS/ALUNORTE Industrial Complex, located in the municipality of Barcarena (PA). For this purpose, chemical analyzes of total fluorine were carried out in soils, plants and waters. In the soils, complementary analyzes of Al, Fe, Ca and Mg, determination of pH and mineralogical composition were also carried out. In addition to the data obtained in laboratories, those made available by the ALBRÁS aluminum factory were also used. For the interpretation of the data, geostatistical techniques and visual analysis of isoteor maps were used, which allowed observing the distribution, albeit in a preliminary way, of fluorine levels in soils, groundwater and grasses. It was verified that there is an impact of the industry on the environment, in its area of influence, evidenced by the increase of contents with time and by the “concentric” distribution of the levels of fluoride found.
Acesso aberto (Open Access)
Contaminação ambiental por mercúrio no distrito mineral de Nambija - Amazônia do Equador
(Universidade Federal do Pará, 2000-08-08) RAMIREZ REQUELME, Marlis Elena; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
Acesso aberto (Open Access)
Dinâmica da distribuição dos poluentes metálicos e orgânicos nos sedimentos de fundo dos canais de drenagem de Belém, Pa
(Universidade Federal do Pará, 1995-10-17) NASCIMENTO, Fernanda Souza do; FENZL, Norbert; http://lattes.cnpq.br/6834981018643186
Acesso aberto (Open Access)
Metais pesados nos arredores de depósitos de lixo de Belém, PA
(Universidade Federal do Pará, 1997-08-27) OLIVEIRA, Alice Helena Pinto de; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
Acesso aberto (Open Access)
Minerais de manganês como contaminantes do minério de ferro na mina N5W em Carajás, Pará
(Universidade Federal do Pará, 2015-09-29) COSTA, Luiz Claudio Gonçalves da; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Mineralogical characterization and control of manganese and silica contents in the Carajás mine iron ore is a routine task. Relatively high concentrations of manganese and silica minerals, considered ore impurities, are present in the high grade iron ore (>65% Fe) of the N5W mine. This study aimed to identify these minerals and their mode of occurrence in the iron ore from N5W, improving the mine planning and exploitation. The main manganese minerals in the iron ore are: (a) pyrolusite, bixbyite, cryptomelane, hollandite, ramsdellite and chalcophanite, all Mn oxy-hydroxides; and (b) the braunite, a silicate. These minerals were found in hydrothermal veins and veinlets, cross-cutting the primary bedding of the iron ore and subordinately forming centimetre scale lens shaped veins, interbedded in the jaspilite layers. The Mn rich veins are spatially associated with fault zones and breccia bodies showing pyrolusite, chalcophanite, braunite and bixbyite veins, subordinated lenses of cryptomelane and hollandite. The presence of pyrolusite and cryptomelane indicates weathering of the rocks. Quartz and Fe-Mn oxy-hydroxides are the main minerals filling faults and fractures in the N5W mine, where MnO grades in veins, reach up to 61,74%. The Mn minerals in the iron ore are indicative of sedimentary and hydrothermal origin. Weathering caused alteration of the primary minerals, promoting mobilization and reprecipitation of new Mn minerals together with Fe oxy-hydroxides. Typical geochemical association in the Mn rich iron ore Mn-As-Cu-Zn-Ag with positive anomalous ETR levels, whilst in the iron formation Zr-Hf-Nb-Ta-Sc-Th with ETR negative values. The rare earth elements concentrations are higher in the Mn rich zones. These zones show strong positive Ce anomalies when hollandite is present. Higher SiO2 contents are related to the presence of metric jaspilite boulders surrounded by hematite friable, in the thick saprolite zone. Finally, the Mn contaminants are diverse in origin, however hydrothermal Mn rich minerals are dominant, closely associated with the proto-iron ore. The high SiO2 contents are indicative of the base of the alteration profile, incorporating part of the proto-ores. Keywords: Mn Oxi-hydroxides; hematite; quartz; silica; contaminants, Carajás Formation.
Acesso aberto (Open Access)
Produção de material zeolítico em escala semi piloto com o calor proveniente da dissolução de hidróxido de sódio
(Universidade Federal do Pará, 2025-02-05) LIMA, Haianny Beatriz Saraiva; COSTA, Deibson Silva da; http://lattes.cnpq.br/1521124351431087; HTTPS://ORCID.ORG/0000-0002-2165-2628; ESTUMANO, Diego Cardoso; http://lattes.cnpq.br/5521162828533153; https://orcid.org/0000-0003-4318-4455
The increasing demand for zeolitic materials, due to their high adsorption capacity, selectivity, and ion exchange, highlights the need for more efficient and sustainable production methods. Thus, the study aimed to produce zeolites on a semi pilot scale from kaolin waste, utilizing reactive heat for hydrothermal synthesis and applying these zeolites for copper ion adsorption. The methodology involved drying, disaggregation, and calcination of the kaolinitic waste, followed by the synthesis of the zeolitic material. Characterization of the materials was performed using X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), and Thermogravimetric Analysis (TGA), Differential Thermogravimetric Analysis (DTG), and Differential Scanning Calorimetry (DSC). Subsequently, equilibrium isotherms were conducted at temperatures of 25 ºC, 35 ºC, 45 ºC, 55 ºC, 65 ºC, 75 ºC, 85 ºC, and 95 ºC, along with parameter estimation to study the adsorption mechanisms and the adsorbate/adsorbent interface. Additionally, modeling of the adsorption process for hydrogen sulfide (H2S) and carbon dioxide (CO2) gases was carried out, using experimental data from the literature and employing analytical breakthrough curve models to describe the adsorption phenomenon in continuous flow. The results confirmed the predominant presence of kaolinite in the waste, the efficiency of the calcination process, and the formation of zeolitic material, evidenced by the mineralogical and chemical composition, as well as the cubic morphology characteristic of zeolite 4A and the spherical shapes of sodalite. Thermal analyses elucidated changes associated with water loss and phase transitions. Adsorption tests demonstrated that the produced material was effective in removing copper ions, with a maximum amount adsorbed of 782,76 mg/g at 95 ºC, indicating a good interaction between the adsorbent and the adsorbate. Furthermore, the use of Bayesian techniques for parameter estimation in isotherm and breakthrough curve models enabled a better understanding of the process dynamics. Finally, this study demonstrated the feasibility of producing zeolites from kaolin residue on a semi-pilot scale using reactional heat, offering an approach that is less harmful to the environment and reduces costs through the reuse of industrial waste and energy optimization of the process.
Acesso aberto (Open Access)
Simulação computacional da adsorção dos poluentes benzeno, tolueno e p-xileno sobre carvão ativado
(Universidade Federal do Pará, 2013-12-27) COSTA, Wanessa Almeida da; MARTELLI, Marlice Cruz; http://lattes.cnpq.br/1213009262936026; BRASIL, Davi do Socorro Barros; http://lattes.cnpq.br/0931007460545219
The greatest problems of groundwater and soil contamination are assigned to monoaromatic hydrocarbons which are the most soluble and the most mobile constituents of the fraction of certain substances, such as gasoline. To remove these contaminants, adsorption by activated carbon is the most widely used method, for it presents a significant ability to adsorb organic low molecular weight components, such as benzene, toluene and p-xylene. In this work, we verified the adsorption on activated carbon thereof via computer simulation. As base, we used the postulated model of charcoal prepared by Bourke et al. (2007). Several steps have been completed since the design of the structures of carbon and pollutants to the molecular dynamics phase. For the conformational analysis of the coal’s structure, it was used the semi-empirical method PM3 and for the molecular dynamics technique, the AMBER force field FF99SB. The structure went through a heating at constant pressure until it reaches a final temperature of 298K (25ºC), being its information collected every 50 ps. Subsequently, the structure was submited to equilibrium system at a constant temperature of 298K (25ºC) for 500ps for its information can be analyzed. Finally, the system was then submited to molecular dynamics during 30ns. After analyzing the results, it was found that the ether, lactone and carbonyl (ketone) groups present in the structure of activated carbon provide to it acid feature and because of this and its consequent negative surface charge, adsorption has become viable once the pollutants had positive surface charge, which supports the view that is already known about this type of phenomenon.