Swelling and aggregation of Leonardite upon pH change and Pb II binding: An AFM study

Environmental context Natural organic materials, such as humic substances, play key roles in the binding and environmental fate of metals. We study the interaction of protons and metal ions with humic acids, and show changes to the mechanical properties of the particles and their capability to fix m...

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Autores principales: Copello, F.D.R., Lizarraga, L., Orsetti, S., Molina, F.V.
Formato: JOUR
Materias:
environmental colloids
metals
soil chemistry
adsorption
atomic force microscopy
colloid
concentration (composition)
environmental fate
experimental study
humic acid
humic substance
ion
lead
pH
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_14482517_v15_n3_p162_Copello
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_14482517_v15_n3_p162_Copello2023-10-03T16:16:30Z Swelling and aggregation of Leonardite upon pH change and Pb II binding: An AFM study Copello, F.D.R. Lizarraga, L. Orsetti, S. Molina, F.V. environmental colloids metals soil chemistry adsorption atomic force microscopy colloid concentration (composition) environmental fate experimental study humic acid humic substance ion lead pH soil chemistry Environmental context Natural organic materials, such as humic substances, play key roles in the binding and environmental fate of metals. We study the interaction of protons and metal ions with humic acids, and show changes to the mechanical properties of the particles and their capability to fix metal pollutants. The results will help refine current models of metal behaviour in the environment. Abstract The swelling and aggregation of Leonardite humic acid, due to acid-base and Pb II binding interactions, was studied through atomic force microscopy (AFM) tapping mode measurements and correlated with potentiometric experiments. These experiments allowed determination of parameters for the non-ideal competitive adsorption (NICA)-elastic polyelectrolyte network (EPN) model, which predicts size and electrostatic potential changes. AFM observations showed growth of agglomerates at low pH values. Height distribution analysis allowed discrimination of single particles from agglomerates. The size of individual particles increased slightly with pH increase. Agglomeration was evaluated through the dispersity, which increased at pH < 5, concomitant with a decrease of the electrostatic repulsion and an increase of protonated carboxylic groups, thus the agglomeration is attributed to both factors. In the presence of Pb II, agglomeration is observed to rise strongly with the increase in metal concentration, which is attributed to bridging of humic particles by Pb II ions. The AFM ex situ results suggest consistency between NICA-EPN predictions and experimental behaviour. © 2018 CSIRO. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_14482517_v15_n3_p162_Copello
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic environmental colloids
metals
soil chemistry
adsorption
atomic force microscopy
colloid
concentration (composition)
environmental fate
experimental study
humic acid
humic substance
ion
lead
pH
soil chemistry
spellingShingle environmental colloids
metals
soil chemistry
adsorption
atomic force microscopy
colloid
concentration (composition)
environmental fate
experimental study
humic acid
humic substance
ion
lead
pH
soil chemistry
Copello, F.D.R.
Lizarraga, L.
Orsetti, S.
Molina, F.V.
Swelling and aggregation of Leonardite upon pH change and Pb II binding: An AFM study
topic_facet environmental colloids
metals
soil chemistry
adsorption
atomic force microscopy
colloid
concentration (composition)
environmental fate
experimental study
humic acid
humic substance
ion
lead
pH
soil chemistry
description Environmental context Natural organic materials, such as humic substances, play key roles in the binding and environmental fate of metals. We study the interaction of protons and metal ions with humic acids, and show changes to the mechanical properties of the particles and their capability to fix metal pollutants. The results will help refine current models of metal behaviour in the environment. Abstract The swelling and aggregation of Leonardite humic acid, due to acid-base and Pb II binding interactions, was studied through atomic force microscopy (AFM) tapping mode measurements and correlated with potentiometric experiments. These experiments allowed determination of parameters for the non-ideal competitive adsorption (NICA)-elastic polyelectrolyte network (EPN) model, which predicts size and electrostatic potential changes. AFM observations showed growth of agglomerates at low pH values. Height distribution analysis allowed discrimination of single particles from agglomerates. The size of individual particles increased slightly with pH increase. Agglomeration was evaluated through the dispersity, which increased at pH < 5, concomitant with a decrease of the electrostatic repulsion and an increase of protonated carboxylic groups, thus the agglomeration is attributed to both factors. In the presence of Pb II, agglomeration is observed to rise strongly with the increase in metal concentration, which is attributed to bridging of humic particles by Pb II ions. The AFM ex situ results suggest consistency between NICA-EPN predictions and experimental behaviour. © 2018 CSIRO.
format JOUR
author Copello, F.D.R.
Lizarraga, L.
Orsetti, S.
Molina, F.V.
author_facet Copello, F.D.R.
Lizarraga, L.
Orsetti, S.
Molina, F.V.
author_sort Copello, F.D.R.
title Swelling and aggregation of Leonardite upon pH change and Pb II binding: An AFM study
title_short Swelling and aggregation of Leonardite upon pH change and Pb II binding: An AFM study
title_full Swelling and aggregation of Leonardite upon pH change and Pb II binding: An AFM study
title_fullStr Swelling and aggregation of Leonardite upon pH change and Pb II binding: An AFM study
title_full_unstemmed Swelling and aggregation of Leonardite upon pH change and Pb II binding: An AFM study
title_sort swelling and aggregation of leonardite upon ph change and pb ii binding: an afm study
url http://hdl.handle.net/20.500.12110/paper_14482517_v15_n3_p162_Copello
work_keys_str_mv AT copellofdr swellingandaggregationofleonarditeuponphchangeandpbiibindinganafmstudy
AT lizarragal swellingandaggregationofleonarditeuponphchangeandpbiibindinganafmstudy
AT orsettis swellingandaggregationofleonarditeuponphchangeandpbiibindinganafmstudy
AT molinafv swellingandaggregationofleonarditeuponphchangeandpbiibindinganafmstudy
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