Utilização de resíduos de grãos de cervejaria na absorção do corante reativo azul 5G em soluções aquosas: sistemas batelada e leito fixo
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2020-02-06
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Universidade Federal de Goiás
Resumo
The textile sector is a major consumer of freshwater and its growing development results in
the generation of large quantities of potentially toxic waste in watercourses, representing a
serious threat to man and the environment. Biological treatment does not always present an
effective solution for this type of effluent, leading to the need to use alternative treatment
processes. Adsorption is an option that stands out due to its high efficiency and versatility,
provided that a viable adsorbent is used for industrial application. This work aimed to study
the adsorption of Reactive Blue 5G dye (RB5G), in a batch and fixed-bed system, using brewer
spent grains (BSG) as an adsorbent. The adsorbent was characterized by particle size analysis,
scanning electron microscopy, infrared spectroscopy, thermogravimetric analysis, and point
of zero charge. A rotational central composite design (RCCD) was carried out in the study of
batch adsorption and a complete factorial planning for the fixed bed, seeking to find conditions
that could favor the dye adsorption process. The characterizations showed that BSG is a
heterogeneous material, with an irregular surface and with the presence of pores, in addition
to having functional groups on its surface that may be involved in the adsorption process. The
adsorption kinetics was obtained, presenting an adsorption equilibrium time of approximately
24 h and a dye removal of 91.5%. Batch adsorption kinetics data were fitted to the pseudo-
first-order and pseudo-second-order models, and the pseudo-second-order model was the one
that best fitted the experimental data. The result of the statistical design performed for the
batch system indicated that the dye adsorption capacity by the BSG was favored when the
highest temperature values and lowest values of pH and mean particle diameter (MPD) were
used. The adsorption isotherm was obtained under conditions capable of maximizing the result
of adsorption capacity, and its data were adjusted to the Langmuir and Freundlich models.
The Langmuir model was the one that best adjusted the isotherm data, reaching a maximum
adsorption capacity of 83.42 mg g-1
. Considering fixed-bed adsorption, the statistical planning
used showed that lower flow rates, associated with higher temperatures and adsorbent
masses, resulted in a better performance of the adsorption column. The equilibrium data for
the fixed bed were found and presented a good fit for both the Langmuir model and the
Freundlich model, which may suggest the coexistence of chemical and physical adsorption. In
general, the BSG showed good results for the adsorption of the dye RB5G, thus being an
alternative for the removal of this dye.
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Citação
COSTA, Fabíola Melazo Amorim Silva. Utilização de resíduos de grãos de cervejaria na absorção do corante reativo azul 5G em soluções aquosas: sistemas batelada e leito fixo. 2020. 102 f. Dissertação (Mestrado em Engenharia Química) - Universidade Federal de Goiás, Goiânia, 2020.