Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water System

Detalhes bibliográficos
Autor(a) principal: Almeida,Vicente R.
Data de Publicação: 2015
Outros Autores: Szpoganicza,Bruno, Bonneville,Steeve
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Journal of the Brazilian Chemical Society (Online)
Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532015000901848
Resumo: Minerals in soils contribute significantly to the capacity of soils to buffer pH disturbance. In this paper, we present the pH buffering capacity of a common soil phyllosilicate mineral, biotite. We performed equilibrium potentiometric titrations and we also monitored the pH response kinetics of the mineral-water system in order to develop an out-of-equilibrium model able to capture the interactions between minerals and the surrounding aqueous fluid. During titrations, after each addition of titrant solution from pH 11 to ca. 3, the pH response patterns were monitored over time until reaching a pseudo-equilibrium pH value. Based on the potentiometric dataset Best7, equilibrium calculations were performed to obtain the concentrations and the equilibrium protonation constants of each deprotonable component that fit best our titration curve. In parallel, the out-of-equilibrium pH responses over time at each point of the titration were used in a simple first-order kinetic approach that allow for the determination of “slow” proton exchange [H+ex]t0(mol L-1) and the associated rate constants for the exchange reactions, k (s-1). Our results show a maximum in “slow” proton exchange [H+ex]t0 associated to a minimal value of k at pH < 5 while at neutral and basic pH exhibits the opposite, i.e. , fast rate constant for a minimum value of the “slow” proton exchange. Expressing the observed “slow” proton exchange processes in terms of entropy production, our result demonstrate that the maximum resilience stability of biotite-water system to pH perturbation is in acidic pH, probably due to the consumption of proton associated with biotite dissolution reactions.
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spelling Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water Systempotentiometric titrationsbiotitelinear out-of-equilibrium thermodynamicssoilsMinerals in soils contribute significantly to the capacity of soils to buffer pH disturbance. In this paper, we present the pH buffering capacity of a common soil phyllosilicate mineral, biotite. We performed equilibrium potentiometric titrations and we also monitored the pH response kinetics of the mineral-water system in order to develop an out-of-equilibrium model able to capture the interactions between minerals and the surrounding aqueous fluid. During titrations, after each addition of titrant solution from pH 11 to ca. 3, the pH response patterns were monitored over time until reaching a pseudo-equilibrium pH value. Based on the potentiometric dataset Best7, equilibrium calculations were performed to obtain the concentrations and the equilibrium protonation constants of each deprotonable component that fit best our titration curve. In parallel, the out-of-equilibrium pH responses over time at each point of the titration were used in a simple first-order kinetic approach that allow for the determination of “slow” proton exchange [H+ex]t0(mol L-1) and the associated rate constants for the exchange reactions, k (s-1). Our results show a maximum in “slow” proton exchange [H+ex]t0 associated to a minimal value of k at pH < 5 while at neutral and basic pH exhibits the opposite, i.e. , fast rate constant for a minimum value of the “slow” proton exchange. Expressing the observed “slow” proton exchange processes in terms of entropy production, our result demonstrate that the maximum resilience stability of biotite-water system to pH perturbation is in acidic pH, probably due to the consumption of proton associated with biotite dissolution reactions.Sociedade Brasileira de Química2015-09-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532015000901848Journal of the Brazilian Chemical Society v.26 n.9 2015reponame:Journal of the Brazilian Chemical Society (Online)instname:Sociedade Brasileira de Química (SBQ)instacron:SBQ10.5935/0103-5053.20150162info:eu-repo/semantics/openAccessAlmeida,Vicente R.Szpoganicza,BrunoBonneville,Steeveeng2015-09-11T00:00:00Zoai:scielo:S0103-50532015000901848Revistahttp://jbcs.sbq.org.brONGhttps://old.scielo.br/oai/scielo-oai.php||office@jbcs.sbq.org.br1678-47900103-5053opendoar:2015-09-11T00:00Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ)false
dc.title.none.fl_str_mv Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water System
title Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water System
spellingShingle Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water System
Almeida,Vicente R.
potentiometric titrations
biotite
linear out-of-equilibrium thermodynamics
soils
title_short Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water System
title_full Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water System
title_fullStr Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water System
title_full_unstemmed Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water System
title_sort Potentiometric Titration and Out-Of-Equilibrium pH Response of the Biotite‑Water System
author Almeida,Vicente R.
author_facet Almeida,Vicente R.
Szpoganicza,Bruno
Bonneville,Steeve
author_role author
author2 Szpoganicza,Bruno
Bonneville,Steeve
author2_role author
author
dc.contributor.author.fl_str_mv Almeida,Vicente R.
Szpoganicza,Bruno
Bonneville,Steeve
dc.subject.por.fl_str_mv potentiometric titrations
biotite
linear out-of-equilibrium thermodynamics
soils
topic potentiometric titrations
biotite
linear out-of-equilibrium thermodynamics
soils
description Minerals in soils contribute significantly to the capacity of soils to buffer pH disturbance. In this paper, we present the pH buffering capacity of a common soil phyllosilicate mineral, biotite. We performed equilibrium potentiometric titrations and we also monitored the pH response kinetics of the mineral-water system in order to develop an out-of-equilibrium model able to capture the interactions between minerals and the surrounding aqueous fluid. During titrations, after each addition of titrant solution from pH 11 to ca. 3, the pH response patterns were monitored over time until reaching a pseudo-equilibrium pH value. Based on the potentiometric dataset Best7, equilibrium calculations were performed to obtain the concentrations and the equilibrium protonation constants of each deprotonable component that fit best our titration curve. In parallel, the out-of-equilibrium pH responses over time at each point of the titration were used in a simple first-order kinetic approach that allow for the determination of “slow” proton exchange [H+ex]t0(mol L-1) and the associated rate constants for the exchange reactions, k (s-1). Our results show a maximum in “slow” proton exchange [H+ex]t0 associated to a minimal value of k at pH < 5 while at neutral and basic pH exhibits the opposite, i.e. , fast rate constant for a minimum value of the “slow” proton exchange. Expressing the observed “slow” proton exchange processes in terms of entropy production, our result demonstrate that the maximum resilience stability of biotite-water system to pH perturbation is in acidic pH, probably due to the consumption of proton associated with biotite dissolution reactions.
publishDate 2015
dc.date.none.fl_str_mv 2015-09-01
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
format article
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dc.identifier.uri.fl_str_mv http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532015000901848
url http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532015000901848
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv 10.5935/0103-5053.20150162
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv text/html
dc.publisher.none.fl_str_mv Sociedade Brasileira de Química
publisher.none.fl_str_mv Sociedade Brasileira de Química
dc.source.none.fl_str_mv Journal of the Brazilian Chemical Society v.26 n.9 2015
reponame:Journal of the Brazilian Chemical Society (Online)
instname:Sociedade Brasileira de Química (SBQ)
instacron:SBQ
instname_str Sociedade Brasileira de Química (SBQ)
instacron_str SBQ
institution SBQ
reponame_str Journal of the Brazilian Chemical Society (Online)
collection Journal of the Brazilian Chemical Society (Online)
repository.name.fl_str_mv Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ)
repository.mail.fl_str_mv ||office@jbcs.sbq.org.br
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