Navegando por Assunto "Zeólita"

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Acesso aberto (Open Access)
Desenvolvimento de processo de zeólita A utilizando o caulim da Amazônia e aplicação na adsorção de Cu+2
(Universidade Federal do Pará, 2014-08-22) MORAES, Cristiane Gomes; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
Around the world millions of tons of inorganic waste are produced every day in mining and mineral processing. These wastes are stored in sedimentation basins or discarded in landfills, and very often are thrown directly into the environment without any treatment process. However, alternative recycling and/or reuse should be investigated and, where possible. This work shows studies in order to reuse the kaolin waste from Amazon, from a kaolin processing company for paper covering. For the synthesis of the zeolite in static and dynamic hydrothermal processes, was used as the silicon source and the aluminum kaolin waste, which passed through the calcination procedure in a muffle at 600°C to obtain metakaolin; and as sodium source chose to 5M sodium hydroxide solution. In the static method was used stainless steel autoclaves, in an oven at 110°C, using 1,75g of metakaolin, varying the time of synthesis and the mass of sodium hydroxide and the dynamic process, we used 100g of metakaolin, mass 34,5g sodium hydroxide; at 95°C under stirring system, varying the time of synthesis, in order to determine the optimal conditions in the synthesis of the zeolite in the process. Matches materials and zeolitic products obtained in the syntheses were characterized by: X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis and thermogravimetric (DTA/TG), X-ray fluorescence (XRF) and particle size analysis. There is the possibility of scale-up, since the zeolite obtained, the dynamic process in time of 30 min. Data from adsorption experiments determined by iodometric technique copper alloys and metal and minerals, adjusted by Langmuir and Freundlich suggest that the static and dynamic zeolitic materials have good adsorptive capacity reached 95% efficiency for concentrations in the range of 50 to 100mg/L, thereby demonstrating that these materials are efficient and cost effective alternative when used for the removal of heavy metals, in the case of copper, the treatment of industrial effluents.
Acesso aberto (Open Access)
Desenvolvimento do processo de síntese da zeólita A e da sodalita a partir de rejeitos de Caulim da Amazônia com aplicações em adsorção
(Universidade Federal do Pará, 2011-08-31) MAIA, Ana Áurea Barreto; POLMANN, Herbert; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; 7501959623721607
The minimization of industrial and domestic residues is one of the great challenges that human kind is facing. Several proposals are released for this intention, ranging from improving industrial processes in order to minimize waste generation, besides their use in the production of new materials. In this context, this work has the main purpose of using kaolin residues from industries located in the Pará State, northern Brazil, for the production of zeolites (e.g., zeolite A and sodalite). These companies exploit kaolin from the world famous Capim and Jari regions and produce high quality kaolin for the paper industry. Preliminary mineralogical and chemical characterization of the Capim (KC) and Jari (KJ) kaolin residues was carried out as the basis for further zeolite A and sodalite synthesis. The study of thermal activation of kaolinite at various temperatures was carried out using 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR), in order to to produce highly reactive metakaolinite from KC and KJ residues. The zeolite NaA synthesis was performed for varying parameters such as time and Na/Al relation. Temperature was kept constant at 110 °C for the two starting materials (KC and KJ). The KA, MgA and CaA phases were prepared by ionic exchange from phase NaA. In the sodalite synthesis, kaolinite was used directly as starting material and two temperatures (150 and 200 °C) were utilized. The Na/anion and Na/Al relations were maintained constant and varied, respectively in the reaction mixture for KC and KJ. The removal performance of mixed metal ions (Co2+, Cr3+, Cu2+, Zn2+ e Ni2+) in aqueous solution was investigated by adsorption process on zeolite NaA prepared from KC an KJ as proposal to reduce environmental problem with industrial wastewater streams that contain heavy metals. The XRD results showed that the residues are mainly composed of kaolinite with extremely low impurity level. For comparing the residues from two regions, Capim and Jari verified that the KC displays a high degree of structural order. This difference displays significant influence in the ideal heating temperature to produce a material with high amount of 4-coordinated A1. As a result, the ideal temperature to produce highly reactive metakaolinite is: 600 °C for Jari kaolin residue and 700 °C for Capim kaolin residue. Zeolite A was produced with a large degree of structural order and was generally obtained as the only zeolitic product. The following synthesis conditions were used: Na/Al ratio of 1.64 and time 18 and 20 h for KC and KJ, respectively. The cationic exchange process between Na from zeolite A and K, Mg and Ca in solutions displays efficient result and with XRD data, was verified that the KA, MgA and CaA phases were obtained with success. The sodalite series was produced from KC and KJ and by FTIR was confirmed the chloride, sulphate and carbonate insertion in its structure. The KJ kaolinite displays high reactivated in the sodalite synthesis, it could be explicated by its low degree of structural order. The sorption capacity of heavy metals mixture (Co2+, Cr3+, Cu2+, Zn2+ e Ni2+) on zeolite NaA, produced from KC and KJ, display satisfactory values. The results revealed that the Langmuir model is more appropriate than Freundlich in the fit of the experimental data. Zeolite A, produced from residues (KC and KJ), could be excellent materials for the treatment of wastewater.
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)
Síntese de zeólitas A e 5A a partir de caulim: uma comparação dos métodos de síntese estático e dinâmico
(Universidade Federal do Pará, 2011-05-11) SANTOS, Suzianny Cristina Arimatéa; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673
Greater awareness of environmental issues and policies on conservation have been doing that arise with new proposals for waste recycling. One of those ways is to reuse the employment of the tailing of the beneficiation of kaolin in zeolite synthesis from kaolin tailing, because zeolites have a wide applicability. Zeolite 5A was synthesized by cation exchange using as starting material zeolite A and calcium solution. We have developed a process for synthesis of zeolite A and zeolite 5A, and the kinetic monitoring of obtaining these crystalline phases and scaling of zeolites A and 5A. The following methods were used: XRD, XRF, SEM, DTA-TG and sieve analysis. It was found that using the two methods of synthesis were obtained zeolites A and 5A, but with only variations in the intensities of their peaks, where the synthesized zeolites in dynamic method showed greater intensity and a greater possibility of scaling up production to 400g. The products were used in zeolite adsorption system, the adsorption tests of moisture in the air the same show promise, arriving adsorb up to 20% on the mass of zeolite. It was found that the new dynamic methodology developed for production of zeolite A in this work proved to be much higher than the previous static approach, because it allowed a greater increase in scale beyond the reduction of synthesis time.