Mercury adsorption on natural and organofunctionalized smectites - thermodynamics of cation removal
A natural smectite clay sample from Piauí State, Brazil, was organofunctionalized with 3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane silyating agents. The basal spacing of 0.99 nm and surface area of 48 m² g-1 for natural clay increased to 1.84 and 2.01 nm, and 781 and 795 m² g-1 for modified clays, respectively. The natural and chemically immobilized clay samples adsorb mercury cations from aqueous solutions at pH 3.0 at 298 ± 1 K. The Langmuir, Redlich-Peterson and Toth adsorption isotherm models were applied to fit the experimental data with a nonlinear approach. From the cation/basic center interactions for each smectite at the solid-liquid interface, by using calorimetry methodology, the equilibrium constant and exothermic thermal effects were obtained. By considering the net interactive number of moles for each cation and the equilibrium constant, the enthalpy, "intHº (-11.98 to -13.93 kJ mol-1) and negative free Gibbs energy, "intGº (-22.4 ± 0.1 to -23.9 ± 0.1 kJ mol-1) were calculated. These values enabled the determination of positive entropy, "intSº (51 ± 01 to 55 ± 2 J K-1 mol-1). The cation-basic center interactions are spontaneous in nature as demonstrated from favorable enthalpic and entropic results. Natural and anchored smectites have the ability to complex mercury, acting as useful materials for removal of this hazardous metal from an ecosystem.
Main Authors: | , , |
---|---|
Format: | Digital revista |
Language: | English |
Published: |
Sociedade Brasileira de Química
2009
|
Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532009000400003 |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
id |
oai:scielo:S0103-50532009000400003 |
---|---|
record_format |
ojs |
spelling |
oai:scielo:S0103-505320090004000032009-06-10Mercury adsorption on natural and organofunctionalized smectites - thermodynamics of cation removalGuerra,Denis L.Santos,Maria R. M. C.Airoldi,Claudio smectite adsorption mercury thermodynamic A natural smectite clay sample from Piauí State, Brazil, was organofunctionalized with 3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane silyating agents. The basal spacing of 0.99 nm and surface area of 48 m² g-1 for natural clay increased to 1.84 and 2.01 nm, and 781 and 795 m² g-1 for modified clays, respectively. The natural and chemically immobilized clay samples adsorb mercury cations from aqueous solutions at pH 3.0 at 298 ± 1 K. The Langmuir, Redlich-Peterson and Toth adsorption isotherm models were applied to fit the experimental data with a nonlinear approach. From the cation/basic center interactions for each smectite at the solid-liquid interface, by using calorimetry methodology, the equilibrium constant and exothermic thermal effects were obtained. By considering the net interactive number of moles for each cation and the equilibrium constant, the enthalpy, "intHº (-11.98 to -13.93 kJ mol-1) and negative free Gibbs energy, "intGº (-22.4 ± 0.1 to -23.9 ± 0.1 kJ mol-1) were calculated. These values enabled the determination of positive entropy, "intSº (51 ± 01 to 55 ± 2 J K-1 mol-1). The cation-basic center interactions are spontaneous in nature as demonstrated from favorable enthalpic and entropic results. Natural and anchored smectites have the ability to complex mercury, acting as useful materials for removal of this hazardous metal from an ecosystem.info:eu-repo/semantics/openAccessSociedade Brasileira de QuímicaJournal of the Brazilian Chemical Society v.20 n.4 20092009-01-01info:eu-repo/semantics/articletext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532009000400003en10.1590/S0103-50532009000400003 |
institution |
SCIELO |
collection |
OJS |
country |
Brasil |
countrycode |
BR |
component |
Revista |
access |
En linea |
databasecode |
rev-scielo-br |
tag |
revista |
region |
America del Sur |
libraryname |
SciELO |
language |
English |
format |
Digital |
author |
Guerra,Denis L. Santos,Maria R. M. C. Airoldi,Claudio |
spellingShingle |
Guerra,Denis L. Santos,Maria R. M. C. Airoldi,Claudio Mercury adsorption on natural and organofunctionalized smectites - thermodynamics of cation removal |
author_facet |
Guerra,Denis L. Santos,Maria R. M. C. Airoldi,Claudio |
author_sort |
Guerra,Denis L. |
title |
Mercury adsorption on natural and organofunctionalized smectites - thermodynamics of cation removal |
title_short |
Mercury adsorption on natural and organofunctionalized smectites - thermodynamics of cation removal |
title_full |
Mercury adsorption on natural and organofunctionalized smectites - thermodynamics of cation removal |
title_fullStr |
Mercury adsorption on natural and organofunctionalized smectites - thermodynamics of cation removal |
title_full_unstemmed |
Mercury adsorption on natural and organofunctionalized smectites - thermodynamics of cation removal |
title_sort |
mercury adsorption on natural and organofunctionalized smectites - thermodynamics of cation removal |
description |
A natural smectite clay sample from Piauí State, Brazil, was organofunctionalized with 3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane silyating agents. The basal spacing of 0.99 nm and surface area of 48 m² g-1 for natural clay increased to 1.84 and 2.01 nm, and 781 and 795 m² g-1 for modified clays, respectively. The natural and chemically immobilized clay samples adsorb mercury cations from aqueous solutions at pH 3.0 at 298 ± 1 K. The Langmuir, Redlich-Peterson and Toth adsorption isotherm models were applied to fit the experimental data with a nonlinear approach. From the cation/basic center interactions for each smectite at the solid-liquid interface, by using calorimetry methodology, the equilibrium constant and exothermic thermal effects were obtained. By considering the net interactive number of moles for each cation and the equilibrium constant, the enthalpy, "intHº (-11.98 to -13.93 kJ mol-1) and negative free Gibbs energy, "intGº (-22.4 ± 0.1 to -23.9 ± 0.1 kJ mol-1) were calculated. These values enabled the determination of positive entropy, "intSº (51 ± 01 to 55 ± 2 J K-1 mol-1). The cation-basic center interactions are spontaneous in nature as demonstrated from favorable enthalpic and entropic results. Natural and anchored smectites have the ability to complex mercury, acting as useful materials for removal of this hazardous metal from an ecosystem. |
publisher |
Sociedade Brasileira de Química |
publishDate |
2009 |
url |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532009000400003 |
work_keys_str_mv |
AT guerradenisl mercuryadsorptiononnaturalandorganofunctionalizedsmectitesthermodynamicsofcationremoval AT santosmariarmc mercuryadsorptiononnaturalandorganofunctionalizedsmectitesthermodynamicsofcationremoval AT airoldiclaudio mercuryadsorptiononnaturalandorganofunctionalizedsmectitesthermodynamicsofcationremoval |
_version_ |
1756403349502033920 |