-This study evaluated the kinetic adsorption of Pb and Cu ions using rice husk ash as adsorbent in a fixed bed. The maximum adsorption capacities obtained for lead and copper ions in the fixed bed were 0.0561 and 0.0682 mmol/g (at 20 °C), respectively. The thermodynamic studies indicated that the lead adsorption process was exothermic and spontaneous, while the copper adsorption process was endothermic and spontaneous. Characterization results indicated the presence of several functional groups, amorphous silica and a fibrous and longitudinal structure of rice husks. Rice husk ash (RHA) from northern Brazil can be used as a bioadsorbent for the individual removal of Pb(II) and Cu(II) ions from metal-containing effluents.
ResumoEste artigo tem como principal objetivo caracterizar argilas esmectíticas chocolate de Boa-Vista, Estado da Paraíba (Brasil) na sua forma natural e após tratamento químico, visando a sua utilização na remoção de Pb 2+ de efluentes sintéticos. Os métodos de caracterização utilizados foram fluorescência de raios X, difração de raios X, microscopia eletrônica de varredura e espectroscopia de raios X por energia dispersiva. Neste trabalho foi estabelecido o procedimento para remoção de Pb 2+ a partir de um efluente inorgânico sintético, utilizando argila natural. Para avaliar a influência dos principais parâmetros, como pH, tratamento e granulometria da argila sobre a remoção do Pb 2+ , foi utilizado o planejamento fatorial e os melhores resultados obtidos foram: pH 4,5, granulometria entre 35 e 48 mesh, e argila natural. Palavras-chave: argilas, caracterização, Troca iônica, chumbo. AbstractThe main objective of this paper is to characterize the Chocolate smectite clays of Boa-Vista, State of Paraíba (Brazil) INTRODUÇÃONos últimos cinqüenta anos, o interesse no estudo em torno das argilas vem crescendo muito, principalmente no que diz respeito à sua composição, estrutura e propriedades fundamentais dos constituintes, não somente das argilas como dos solos. As formas de ocorrência e a relação das argilas com suas propriedades tecnológicas têm sido também muito estudadas [1]. Devido ao seu baixo custo, elas podem ser utilizadas como carga nas indústrias de plásticos, tintas, inseticidas, produtos farmacêuticos e veterinários, com a finalidade de aumentar o volume e modificar as propriedades destes materiais [2].Segundo Souza Santos [3], a argila é um material natural, terroso, de granulometria fina, que geralmente adquire, quando umedecido com água, certa plasticidade, e rigidez depois de submetidos a aquecimento adequado.No conceito moderno, consideram-se as argilas como compostas essencialmente de partículas extremamente pequenas de um ou mais membros de um certo grupo de substâncias denominadas argilominerais [4], que são silicatos hidratados de alumínio e/ou magnésio, contendo teores significativos de ferro, níquel, cromo e outros cátions na estrutura peculiar dos argilominerais que geram uma capacidade de troca reversível para cátions orgânicos, inorgânicos e organometálicos [2].O desenvolvimento industrial e o surgimento de novas tecnologias ocorrido nas últimas décadas fizeram com que o homem começasse a se preocupar com os problemas
To investigate the dryer performance for treatment of infectious hospital waste (IHW), drying kinetics, volume, and microbiological load reduction characteristics were studied. A surrogate waste and B. subtilis (BSN) were used for effectiveness testing of the drying. Satisfactory performance was found for microbiological load reduction. The study of a thermal inactivation kinetics of the BSN shows that a reduction of 6 orders of magnitude occurred in 42 min. The volume reduction obtained was equal to 30-50% after drying. The results obtained were comparable to results from IHW treatment technologies currently in operation.
The aim of this work was an experimental and theoretical investigation of the influence of electrolyte (NaCl) and surfactant (SP), as textile auxiliary agents (TAAs), onto reactive blue 5G (RB5G) dye removal by applying untreated fish scales (FS) in batch system. Kinetic and equilibrium studies were performed, aiming at the comprehension of the mass transfer mechanisms through phenomenological modeling. The biosorbent was texturally characterized, to investigate the adsorbent's characteristics and to support the models' assumptions. Hence, a 'physically meaningful' modeling to assess different systems containing dye-TAA mixtures was employed. The experimental results indicated that despite the FS nonporous characteristics, it showed remarkable adsorption capacities (≈291 mg g-1), which may be ascribed to the adsorbent-adsorbate affinity and to dye-aggregates adsorption onto the FS surface. Those results evidence a potential use of FS as an alternative biosorbent material. The mathematical model was able to identify the rate-limiting step of the process; to predict the adsorption kinetics and equilibrium condition, comprising the description of aggregates formation; and to successfully predict kinetic behavior of independent data in simulated real effluent. Those results indicate that the model can be used to simulate operating conditions and, therefore, support the design, optimization, and scale-up of adsorption processes.
-The bentonitic clays show good adsorptive characteristics, being used as alternative material for removing metals. This study evaluates several treatments (calcination, acid activation and treatment with sodium) of bentonite type Bofe in the removal of nickel and copper. Analyses were performed for physicochemical characterization of clay using the techniques: X-ray fluorescence (XRF), thermal analysis (TG and DTA), X-ray Diffraction (XRD), the ethylene glycol monoethyl ether (EGME) method, N 2 adsorption (BET) and Scanning Electron Microscopy (SEM). Among the changes induced by acid activation and sodium transformations, the treatment with sodium chloride in fixed bed showed the highest performance in the monocomponent removal of nickel and copper.
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