Biossorção do corante Amarelo Reafix B8G a partir do bagaço de malte em batelada e sistema contínuo: avaliação experimental e simulação fluidodinâmica computacional
The objective of this work was the evaluation of malt bagasse as a biosorbent in the removalof Reafix B8G Yellow dye. Experimental batch tests, continuous system and computational fluid dynamics simulation (CFD) were performed. The biosorbent was characterized by the determination of the mean partic...
| Autor principal: | Silva, Bruna Cassia da |
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| Formato: | Dissertação |
| Idioma: | Português |
| Publicado em: |
Universidade Tecnológica Federal do Paraná
2019
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| Assuntos: | |
| Acesso em linha: |
http://repositorio.utfpr.edu.br/jspui/handle/1/4040 |
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| Resumo: |
The objective of this work was the evaluation of malt bagasse as a biosorbent in the removalof Reafix B8G Yellow dye. Experimental batch tests, continuous system and computational fluid dynamics simulation (CFD) were performed. The biosorbent was characterized by the determination of the mean particle diameter, point of zero charge, morphology by scanning electron micrograph, functional groups by Fourier Transform Infrared Spectrometry (FTIR) and specific surface area by N2 fisisorption. The batch tests were performed under different operating conditions (pH, mean particle size, contact time, initial concentration and temperature). The dye recovery was evaluated by batch desorption using different eluents. Continuous biosorption occurred in a fixed bed column and was evaluated through the breakthrough curves and the mass transfer parameters obtained under different operating conditions (flow and concentration). Finally, for the CFD simulation, a model integrated to the ANSYS Fluent 19.0 commercial code was implemented. This model was composed of equations describing biosorption, which includes: mass balance in the liquid phase, solid phase (diffusive kinetic model of resistance to internal mass transfer) and equilibrium between phases (adsorption isotherm). These equations, together with the equations associated with fluid flow, were solved. This allowed to obtain simulated breakthrough curves and dye concentration profiles in the bed, under the same experimental conditions and parameters. Among the characterizations, the FTIR technique showed a possible mechanism of biosorption associated with dye adsorption at the active sites of the hydroxyl (OH) groups of the biosorbent cellulose. The batch evaluation showed equilibrium time less than 24 hours, for all the evaluated temperatures. And the best percentages of removal were achieved for lower concentration ranges. Regarding the temperature, both the evaluation of the contact time and the concentration, there was evidence of an optimum temperature (30 °C). The kinetics was better represented by the pseudo-second order model and showed a fisisorption process, with activation energy of 24.10 kJ mol-1. The biosorption equilibrium was best represented by the Langmuir-BET combined isotherm, which indicates that the adsorption can occur by a monolayer and superimposed multilayers process. The adsorption thermodynamics were evaluated for each of these steps, which presented a spontaneous, exothermic and increased disorder in the solid/solution interface. With respect to the desorption, the recovery of a high percentage of dye (94%) was verified, using ethyl alcohol as eluent. The biosorption in continuous system presented removal capacity superior to the batch removal, with the breakthrough curves strongly influenced by the operating conditions. In the fluid dynamics simulations, it was possible to verify that the integrated model could demonstrate the saturation of the bed. However, the simulated breakthrough curves showed different behavior of the experimental curves, possibly due to the lack of mass transfer resistance effects. Based on the experimental results, it is possible to affirm that malt bagasse presents a significant capacity to treat wastewaters containing the reactive yellow dye. |
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