Usos de membranas de quitosana na remoção de cobre em águas residuais
In this work a chitosan (CS) ionically crosslinked were manufactured by treatment with sulfuric acid solution for application in the treatment of wastewater from oil industry. Two crosslinking process were developed: homogeneous and heterogeneous. In the homogeneous process the ratio molar of SO4...
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| Formato: | doctoralThesis |
| Idioma: | por |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/21136 |
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| Resumo: | In this work a chitosan (CS) ionically crosslinked were manufactured by treatment with
sulfuric acid solution for application in the treatment of wastewater from oil industry. Two
crosslinking process were developed: homogeneous and heterogeneous. In the homogeneous
process the ratio molar of SO42-/ NH3+ (1:6 and 1:4) were the variable analyzed, denominated
CS16 and CS14 respectively. In the heterogeneous process the soaking time of the membranes in
sulfuric acid solution were the variable studied, being used times of 5 (CS5) and 30 (CS30)
minutes. FTIR-ATR results indicated no changes in the characteristics of chitosan after
homogeneous crosslinking process, while heterogeneous crosslinking showed formation of ionic
bonds between protonated groups from chitosan and the crosslinking agent sulfate ions. TG/DTG
and XRD analysis confirmed the formation of these interactions, as also shown the new structure
on the surface region of CS5 and CS30 membranes compared to CS, CS16 e CS14. Swelling test
in aqueous medium have shown that crosslinking process reduced the membrane sorption
capacity. Swelling test in acid medium demonstrated that CS16 and CS14 membranes increasing
the adsorption capacity up to a maximum percentage of 140% approximately, whereas the CS5 e
CS30 reached a maximum of 60%. The mechanical properties indicated the stiff and ductile
behavior of crosslinked membrane. Adsorption experiments of CuCl2 results that CS16
membranes reached the efficiency maximum with 73% of copper removal at pH 5.0 and 87% at
pH 4.0. The experiments with CuSO4 also obtained efficiency maximum to the CS16 membrane
and 80% to the removal of Cu2+ ions. Also was verified that the increase of concentration and
temperature cause a decrease in the adsorption capacity for all membranes. Kinetics study
indicated that pseudo-second-order obtained characterized better the membranes. Equilibrium
studies demonstrated that the CS, CS16 and CS14 follow the Langmuir model, whereas CS5 and
CS30 follows Freundlich model. Filtration experiments results with rejection maximum to the
CS16 and CS5 membranes, reaching 92 and 98% respectively. |
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