Chemical modification of in natura collagen by acidic catalysis – structural characterization and mechanistic features of Cd(II) sorption by solution microcalorimetry

Fernanda Santos Carvalho dos Anjos, Esdras Santos Silva, Marcos Antonio Santana Andrade Jr, Eunice Fragoso da Silva Vieira, Antonio Reinaldo Cestari

Resumo


Chemically-modified in natura collage was prepared under acidic catalysis for using in sorption of Cd(II)
from aqueous solutions. Simultaneous determination of the quantity and energetic parameters of Cd(II) sorption
on PGA-scale at pH 8.0 were determined using solution microcalorimetry (SM). The calorimetric enthalpies
of Cd(II) sorption on PGA-scale are all exothermic, and Cd(II) adsorption energies decrease as temperature
increases. The maximum sorption capacity of PGA-scale for Cd(II) (438 μmol g-1) is superior with
many sorption data reported in the literature. Characterization and SM indicate that the main sites for Cd(II)
sorption are located in the collagen structure of PGA-scale. It was found that the interactions PGAscale/
Cd(II) are mainly due to chemisorption and diffusion may occur at the PGA-scale/Cd(II) interface. The
results of this study underline the good features of PGA-scale as a promising material for sorption of Cd(II)
from aqueous media.
Keywords: Cadmium; biosorbents; fish scales; acidic catalysis; solution microcalorimetry; thermodynamics.

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