Navegando por Assunto "Metals"

Agora exibindo 1 - 6 de 6

Acesso aberto (Open Access)
Distribuição geoquímica dos metais no material particulado em suspensão - MPS na margem direita da Baia de Marajó, Costa Amazônica, Brasil
(Universidade Federal do Pará, 2025-03-25) ANDRADE, Robinson da Cruz; KUTTER, Vinicius; http://lattes.cnpq.br/6652786694334612; https://orcid.org/0000-0001-7295-6800
The Marajó Bay, located in the Amazon region, is one of the largest estuarine systems in Brazil. It is influenced by the Amazon and Tocantins Rivers, with intense hydrodynamics and physico-chemical processes that affect metal distribution. This study aimed to analyze the concentrations and distribution of the elements Al, Fe, Mn, Mg, Zn, Cr, V, Ti, and Ca in suspended particulate matter (SPM) from the right margin of Marajó Bay, correlating the results with environmental factors such as salinity, pH, and local hydrodynamics. Samples were collected at three strategic points— Icoaraci (Point 1), Mosqueiro Island (Point 2), and Colares (Point 3) — during two campaigns carried out between April and May 2023. A Van Dorn bottle was used for surface and 20-meter depth sampling, covering the complete tidal cycle. The particulate material was filtered using cellulose acetate filters (0.45 μm) and analyzed by X-ray fluorescence spectrometry for quantitative determination of the elements. Physico-chemical data such as temperature, pH, salinity, and Eh were obtained using multiparameter probes, and current data using ADCP. Statistical analysis included Kruskal-Wallis tests, Pearson correlations, and boxplots. The results revealed significant variations in SPM concentrations among the sampling points. At Point 3 (Colares), the highest concentrations were observed at the surface (0.278 mg/L), indicating lower hydrodynamic energy and greater deposition of fine sediments, favored by saline intrusion and metal flocculation. Point 1 (Icoaraci) showed the lowest concentrations, suggesting higher sediment removal due to tidal dynamics and river discharge. The Kruskal-Wallis test indicated significant differences among surface samples, especially for Mg, Al, Ti, V, Cr, Fe, and Zn. At depth, only Mg and Zn showed significant variations. Pearson correlations revealed strong associations between Fe, Cr, Mn, and Zn at Point 3, suggesting co-transport of these metals, likely governed by adsorption onto iron and manganese oxides, particularly under low-energy conditions. The observed geochemical behavior highlights that hydrodynamics and saline intrusion are key factors controlling the spatial and vertical distribution of metals in Marajó Bay. It is concluded that Marajó Bay is a highly dynamic estuarine environment, where the deposition and transport of metals in SPM are controlled by both physical processes, such as hydrodynamic variation, and chemical processes, such as flocculation in saline environments. The findings contribute to the understanding of geochemical processes in the Amazon region and provide valuable insights for environmental management and the preservation of local ecosystems.
Acesso aberto (Open Access)
Estudo da extração de cobre utilizando contactores com membranas como alternativa ao processo convencional de extração por solvente
(Universidade Federal do Pará, 2013-12-27) OLIVEIRA, Kleber Bittencourt; FERRAZ, Helen Conceição; http://lattes.cnpq.br/1820877582714129; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
This paper studied the extraction of copper using membrane contactors as an alternative to conventional SX process. The relevant process parameters as type and concentration of extractant solvent, the strip solution, operating time and pH were investigated. Furthermore, a mathematical model was developed from a system of partial differential equations resulting from the mass balance in the membrane contactor system, using as the solution methodology of Integral Technique Coupled (CIEA). The experimental studies conducted in this study showed that use of membrane contactors in liquid-liquid extraction of copper is a promising and viable technology, with the potential to replace the method of solvent extraction by direct contact adopted currently yielding 100% extraction LIX 84I copper using 20% (v/v) as extractant, kerosene as solvent and H2SO4 strip solution in an operation time of 80 minutes. The results obtained by mathematical modeling and simulation of the physical problem analyzed in this study were compared with experimental results and shown to be satisfactory, demonstrating the ability of CIEA in treating problems of mass transfer in membrane systems with contactor.
Acesso aberto (Open Access)
Modelagem e simulação do processo de separação por membrana difusa polimérica para a extração de metais
(Universidade Federal do Pará, 2007-02-16) CARDOSO, Simone de Aviz; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
Metal extraction process using polymeric membranes is analyzed by using the lines-Gear method in the solution of the related equations of specie conservations. The mathematical modeling of the physical problem is done by considering the diffusion process of metals in polymeric membranes in order to extract metals, such as Cd (II), Au (III) and Pd (II) from acid solutions. Therefore, the behavior of concentration profiles of metals to be extracted from the feeding phase is discussed in the light of the influence of relevant parameters in the extraction process, such as, composition and thickness of the membrane, diffusion coefficient and constant extraction. Comparisons with previously reported results in the literature for typical situations are also performed. The obtained results were very satisfactory when they were compared with other found results in the literature.
Acesso aberto (Open Access)
Modelagem, simulação e estimação dos parâmetros por MCMC de um modelo que descreve a dinâmica de adsorção em uma coluna de leito fixo
(Universidade Federal do Pará, 2023-01-18) SOEIRO, Wilhamis Fonseca; VIEGAS, Bruno Marques; http://lattes.cnpq.br/1196600058247902; HTTPS://ORCID.ORG/0000-0002-2768-652X; ESTUMANO, Diego Cardoso; http://lattes.cnpq.br/5521162828533153; https://orcid.org/0000-0003-4318-4455
The treatment of industrial effluents is extremely important for both the environment and human health. The purification of water from polluting components, such as metals and organic compounds, for reuse in the industrial process can be considered one of the main applications in this field. Therefore, there is interest in modeling one of the most used treatment processes, adsorption. Aiming to describe the dynamics of the process in an adsorption column, in this work the method of lines and the pdepe function (matlab) are used to solve the model formed by the mass balance in the liquid phase, linear driving force equation (LDF) and the Langmuir isotherm for equilibrium. An evaluation of the model varying some experiment conditions was carried out, from which results congruent with those found in the literature were observed. In addition, a sensitivity analysis of the phenomenon was carried out in relation to the parameters: Langmuir constant, intraparticle mass transfer coefficient and axial dispersion coefficient. Subsequently, these parameters were estimated using the Monte Carlo technique via Markov chain (MCMC) using experimental data found in the literature. Finally, in general, the estimates were good enough to represent the adsorption dynamics of the evaluated experiments.
Acesso aberto (Open Access)
Produção de zeólita a partir de cinza volante de carvão mineral para adsorção de metais em chorume gerado no lixão/aterro controlado na Região Amazônica
(Universidade Federal do Pará, 2022-01-28) DIAS, Lianne Maria Magalhães; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
The formation of solid waste has become a great challenge for the environment preservation due to the lifestyle adopted by modern society, which seeks for practicality and immediacy, and by that, new products are released, and waste formation is increased. The decomposition of waste from various sources creates a dark liquid denominated “slurry”, which presents high concentration of organic and inorganic compounds. This study aimed to evaluate the concentrations of Cd, Cu, Cr, Mn, Ni, Pb, and Zn on the ground and percolated liquid produced at the solid waste decomposition site in the metropolitan region of Belém/Pará/Brazil. Fly ashes of mineral coal were used to produce a low-cost zeolitic material, for removing copper, zinc, cadmium, and chrome, which are present at the percolated liquid of the Aurá landfill. The zeolites synthesized by alkaline fusion (ZSH and ZSJ), and without alkaline fusion (ZSD, ZSG, ZSK, ZSO), were characterized by different techniques, such as X-ray fluorescenc espectrometry, X-ray diffraction, and Scanning Electron Microscopy. The treatment adsorption efficiency of using adsorbent zeolitic material demonstrated viability to be used as an adsorvent agent for the adsorption of metals present at the leachate produced by landfills.
Acesso aberto (Open Access)
A técnica da transformada integral na modelagem e simulação de processos de separação de metais por membranas difusivas poliméricas
(Universidade Federal do Pará, 2012-11) CARDOSO, Simone de Aviz; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
The Generalized Integral Transform Technique (GITT) was used in the analysis of the metal extraction process with flat and tubular membranes. For the study of flat membrane, we analyzed the extraction of metals cadmium, Cd (II), gold, Au (III) and palladium, Pd (II) in polymeric diffusive membrane with Aliquat 336/PVC and the equations of chemical species were solved by the GITT methodology. In a second study, the Coupled Integral Equations Approach (CIEA) was used to analyze the same problem. In the study of hollow-fiber tubular membrane, the GITT methodology was also utilized for analyzing the influence of transport conditions for the solute of interest at the interface fluid and membrane phases of a mass separation process in tubular membranes as a function of the governing parameters of the problem. In this type of extraction, liquid extractants are used in the pores of the fiber membrane to facilitate the separation of the mass. In both studies, comparisons were made with those results from the literature demonstrating the potential of this technique in dealing with problems of such natures.