Kinetic Study of the Effect of pH on Hexavalent and Trivalent Chromium Removal from Aqueous Solution by <Emphasis Type="Italic">Cupressus lusitanica</Emphasis> Bark |
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Authors: | Alma Rosa Netzahuatl-Muñoz Flor de María Guillén-Jiménez Benjamín Chávez-Gómez Thelma Lilia Villegas-Garrido Eliseo Cristiani-Urbina |
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Institution: | 1.Universidad Politécnica de Tlaxcala,Tepeyanco,Mexico;2.Departamento de Ingeniería Bioquímica, Escuela Nacional de Ciencias Biológicas,Instituto Politécnico Nacional,Mexico,Mexico;3.Instituto Mexicano del Petróleo,Mexico,Mexico;4.Departamento de Biofísica, Escuela Nacional de Ciencias Biológicas,Instituto Politécnico Nacional,Mexico,Mexico |
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Abstract: | Solution pH is among the most important parameters that influence heavy metal biosorption. This work presents a kinetic study
of the effects of pH on chromium biosorption onto Cupressus lusitanica Mill bark from aqueous Cr(VI) or Cr(III) solutions and proposes a mechanism of adsorption. At all assayed contact times,
the optimum pH for chromium biosorption from the Cr(III) solution was 5.0; in contrast, optimum pH for chromium biosorption
from the Cr(VI) solution varied depending on contact time. The kinetic models that satisfactorily described the chromium biosorption
processes from the Cr(III) and Cr(VI) solutions were the Elovich and pseudo second-order models, respectively. Diffuse reflectance
infrared Fourier transform spectroscopy studies suggest that phenolic compounds present on C. lusitanica Mill bark play an important role in chromium biosorption from the Cr(III) solution. On the other hand, chromium biosorption
from the Cr(VI) solution involved carboxyl groups produced on the bark by redox reactions between oxygen-containing groups
and Cr(VI), and these were in turn responsible for the biosorption of Cr(III) produced by Cr(VI) reduction. |
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