Estudo de metodologias de tratamento do pó da casca do coco para adsorção de Cu+2 e Cd+2
In view of the environmental problem of the pollution of water bodies by heavy metals, caused by human activities in general, and the inadequate destination of certain solid agro-industrial residues, there is a great need to develop research that improves the technique of removing these inorganic...
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| Muut tekijät: | |
| Aineistotyyppi: | doctoralThesis |
| Kieli: | pt_BR |
| Julkaistu: |
Universidade Federal do Rio Grande do Norte
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| Aiheet: | |
| Linkit: | https://repositorio.ufrn.br/jspui/handle/123456789/30109 |
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| Yhteenveto: | In view of the environmental problem of the pollution of water bodies by heavy metals, caused
by human activities in general, and the inadequate destination of certain solid agro-industrial
residues, there is a great need to develop research that improves the technique of removing these
inorganic pollutants from aqueous solutions. One way would be to take advantage of agroindustrial waste as agents that remove these pollutants. As the coconut shell powder (CP) is a
residue generated from its processing, the present work aims to provide studies related to three
treatment methodologies so that the CP adsorption capacity be empowered and then be reused
to remove two toxic metals widely found in wastewater, Cu+ 2
and Cd+ 2 that are widely found in wastewater from effluents from the mining, metallurgy and dye industries. The applied methodologies included the physical and chemical treatment of the PC surface, developed
separately, according to the sequence: chemical treatment through the impregnation of
Monoethanolamine in the proportion 1: 1, using ethanol as solvent; chemical treatment through
the impregnation of the sodium octanoate surfactant by microemulsion; and physical
modification using the steam explosion technique (T = 210 °C and P = 5 atm). The efficiency
of the proposed treatments was evaluated through characterization analyzes, where changes
were observed in the specific contact area, chemical composition and crystallinity of the
adsorbent material. The evaluation of the monocomponent adsorption capacity of Cu+2
and Cd+2 ions in the PC was performed using a batch mixing reactor of the synthetic solutions of
CuSO4.5H2O and CdSO4.8/3H2O. After chemical treatment, the insertion of functional groups
increased the metal - adsorbent interaction confirmed by the values of the kinetic constants of
the studied models. It was observed that the coconut shell powder impregnated with OS (PCµE)
adsorbed more Cu + 2 ions in relation to the impregnated with MEA (PCA). The treatment with
steam explosion, depolymerized the coconut shell powder (PCD), which caused an increase in
the total pore volume and crystallinity, consequently, making the adsorbent surface more
accessible for adsorption. The behavior of equilibrium isotherms is satisfactorily represented
by the Langmuir model and the adsorption capacities (mg / g) of the coconut shell powder after
treatments follow the order: PCµE (26.32)> PCD (18.86)> PCA (15.94)> PC (7.88) for Cu+2
and PCD ions (17.90)> PCA (14.02)> PC (4.91) for Cd+2 ions, respectively, emphasizing that
the impregnation methodology with surfactants did not significantly improve the interaction of
PC with Cd+2. The stability of the impregnation with MEA and OS was evaluated from the
desorption study. After the adsorption-desorption cycles, the amount of Cu+2
adsorbed on the PCµE decreased by 36.6%, while for the PCA the reduction was 22.8%. Regarding the
adsorption of Cd+2, a reduction of 14% and 10% was observed for PCµE and PCA, respectively.
This shows that, after the five adsorption-desorption cycles, the impregnation of
monoethanolamine in the coconut shell powder is stronger, remaining with greater removal
than the PCµE and thus, it can be reused for more cycles in the adsorption-desorption process. |
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