Removal of toxic metals from wastewater by Brazilian natural scolecite.
J Colloid Interface Sci
; 281(2): 424-31, 2005 Jan 15.
Article
em En
| MEDLINE
| ID: mdl-15571698
The cation-exchange capacity of Brazilian natural zeolite, identified as scolecite, was studied with the aim of evaluating its applications in wastewater control. We investigated the process of sorption of chromium(III), nickel(II), cadmium(II), and manganese(II) in synthetic aqueous effluents, including sorption isotherms of single-metal solutions at 298, 313, and 333 K, by batch experiments, and the influence of pH on the process. The results have demonstrated that removal of metals from specific metal solutions is best described by a Freundlich isotherm, in which the values obtained for the Kf constants were in the following order: Cr > Mn > Cd > Ni. A Lagergren pseudo-second-order was the model that best described the sorption mechanism. The retention of metals was shown to be a function of the pH; the maximum binding capacity occurring at pH values around 6.0. Thermodynamic data indicate the spontaneity of the endothermic cation-exchange process. The values of Delta G0 suggest the following selectivity series at 298 K: Ni > Cr > Cd > Mn. The desorption process reaches equilibrium during the first 60 min of binding, suggesting that the mechanism involves specific sites located in the external surface of the scolecite.
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Coleções:
01-internacional
Base de dados:
MEDLINE
País/Região como assunto:
America do sul
/
Brasil
Idioma:
En
Revista:
J Colloid Interface Sci
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Estados Unidos