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Measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange

In soil and water, metal complexation by humic substances has been demonstrated to have great importance in determining the bioavailability of many trace metals including lead. The binding of lead by humic acids has important implications for lead toxicity, and remediation. In this study we demonstr...

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Autores principales: Steinberg, Spencer M., Hodge, Vernon F.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9798188/
https://www.ncbi.nlm.nih.gov/pubmed/36590533
http://dx.doi.org/10.1016/j.heliyon.2022.e12437
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author Steinberg, Spencer M.
Hodge, Vernon F.
author_facet Steinberg, Spencer M.
Hodge, Vernon F.
author_sort Steinberg, Spencer M.
collection PubMed
description In soil and water, metal complexation by humic substances has been demonstrated to have great importance in determining the bioavailability of many trace metals including lead. The binding of lead by humic acids has important implications for lead toxicity, and remediation. In this study we demonstrate the use of 4-(2-pyridylazo)-resorcinol (PAR) as a competitive ligand for the purposed of determining sorption isotherms for Pb(2+) on humic acids and humic acid analogs. Equilibration rates at pH 8 were very rapid and the sorption isotherms measured were fit to the Langmuir isotherm equation and values for the stability constants (K(HA)) and complexing site concentrations (L(t)) are reported. At a PAR concentration of 0.24 mM and humic acid concentrations of 25–200 mg/L, the mass normalized log K(HA) values for the humic substances ranged from 7.2 to 7.9, while the log L(t) values ranged from −2.8 to −3.8. At lower PAR concentrations both K(HA) and L(t) tended to increase in magnitude indicating the role of the PAR concentration in establishing the measurement window for the interaction of Pb(2+) with humic materials.
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spelling pubmed-97981882022-12-30 Measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange Steinberg, Spencer M. Hodge, Vernon F. Heliyon Research Article In soil and water, metal complexation by humic substances has been demonstrated to have great importance in determining the bioavailability of many trace metals including lead. The binding of lead by humic acids has important implications for lead toxicity, and remediation. In this study we demonstrate the use of 4-(2-pyridylazo)-resorcinol (PAR) as a competitive ligand for the purposed of determining sorption isotherms for Pb(2+) on humic acids and humic acid analogs. Equilibration rates at pH 8 were very rapid and the sorption isotherms measured were fit to the Langmuir isotherm equation and values for the stability constants (K(HA)) and complexing site concentrations (L(t)) are reported. At a PAR concentration of 0.24 mM and humic acid concentrations of 25–200 mg/L, the mass normalized log K(HA) values for the humic substances ranged from 7.2 to 7.9, while the log L(t) values ranged from −2.8 to −3.8. At lower PAR concentrations both K(HA) and L(t) tended to increase in magnitude indicating the role of the PAR concentration in establishing the measurement window for the interaction of Pb(2+) with humic materials. Elsevier 2022-12-20 /pmc/articles/PMC9798188/ /pubmed/36590533 http://dx.doi.org/10.1016/j.heliyon.2022.e12437 Text en © 2022 The Author(s) https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Research Article
Steinberg, Spencer M.
Hodge, Vernon F.
Measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange
title Measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange
title_full Measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange
title_fullStr Measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange
title_full_unstemmed Measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange
title_short Measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange
title_sort measurement of lead complexation by humic acids and humic acid analogues using competitive ligand exchange
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9798188/
https://www.ncbi.nlm.nih.gov/pubmed/36590533
http://dx.doi.org/10.1016/j.heliyon.2022.e12437
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