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Strength of Flocs Formed by the Complexation of Lysozyme with Leonardite Humic Acid

Aggregation and aggregates properties of natural organic and nanosized macromolecules such as humic substances and proteins are crucial to explore so-called colloid-mediated transport and the fate of substances in soil and water environments. Therefore, the aggregation and dispersion, charging, and...

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Autores principales: Wan Abdul Khodir, Wan Khairunnisa, Hakim, Azizul, Kobayashi, Motoyoshi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463964/
https://www.ncbi.nlm.nih.gov/pubmed/32784682
http://dx.doi.org/10.3390/polym12081770
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author Wan Abdul Khodir, Wan Khairunnisa
Hakim, Azizul
Kobayashi, Motoyoshi
author_facet Wan Abdul Khodir, Wan Khairunnisa
Hakim, Azizul
Kobayashi, Motoyoshi
author_sort Wan Abdul Khodir, Wan Khairunnisa
collection PubMed
description Aggregation and aggregates properties of natural organic and nanosized macromolecules such as humic substances and proteins are crucial to explore so-called colloid-mediated transport and the fate of substances in soil and water environments. Therefore, the aggregation and dispersion, charging, and floc strength of lysozyme (LSZ)–leonardite humic acid (LHA) flocs were experimentally investigated. The experiments were performed in different salt concentrations and LSZ to LHA mass ratios as a function of pH. We obtained the stronger flocs at pH 4.4, where the isoelectric point (IEP) of the complex with the mass ratio 2.5 was confirmed. Thus, the aggregation of LSZ–LHA flocs is mainly caused by charge neutralization. We obtained the floc strength of 4.7 nN around IEP at low salt concentration of 3 mM, which was stronger than 2.8 nN in high salt concentration of 50 mM. The effect of salt concentration can be rationalized by charge-patch attraction at low salt concentration. With increasing mass ratio, the IEP shifted to higher pH. This is due to the increase in positive charge from LSZ in the mixture. The effect of the LSZ to LHA mass ratio on the maximum strength was weak in the range studied.
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spelling pubmed-74639642020-09-04 Strength of Flocs Formed by the Complexation of Lysozyme with Leonardite Humic Acid Wan Abdul Khodir, Wan Khairunnisa Hakim, Azizul Kobayashi, Motoyoshi Polymers (Basel) Article Aggregation and aggregates properties of natural organic and nanosized macromolecules such as humic substances and proteins are crucial to explore so-called colloid-mediated transport and the fate of substances in soil and water environments. Therefore, the aggregation and dispersion, charging, and floc strength of lysozyme (LSZ)–leonardite humic acid (LHA) flocs were experimentally investigated. The experiments were performed in different salt concentrations and LSZ to LHA mass ratios as a function of pH. We obtained the stronger flocs at pH 4.4, where the isoelectric point (IEP) of the complex with the mass ratio 2.5 was confirmed. Thus, the aggregation of LSZ–LHA flocs is mainly caused by charge neutralization. We obtained the floc strength of 4.7 nN around IEP at low salt concentration of 3 mM, which was stronger than 2.8 nN in high salt concentration of 50 mM. The effect of salt concentration can be rationalized by charge-patch attraction at low salt concentration. With increasing mass ratio, the IEP shifted to higher pH. This is due to the increase in positive charge from LSZ in the mixture. The effect of the LSZ to LHA mass ratio on the maximum strength was weak in the range studied. MDPI 2020-08-07 /pmc/articles/PMC7463964/ /pubmed/32784682 http://dx.doi.org/10.3390/polym12081770 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Wan Abdul Khodir, Wan Khairunnisa
Hakim, Azizul
Kobayashi, Motoyoshi
Strength of Flocs Formed by the Complexation of Lysozyme with Leonardite Humic Acid
title Strength of Flocs Formed by the Complexation of Lysozyme with Leonardite Humic Acid
title_full Strength of Flocs Formed by the Complexation of Lysozyme with Leonardite Humic Acid
title_fullStr Strength of Flocs Formed by the Complexation of Lysozyme with Leonardite Humic Acid
title_full_unstemmed Strength of Flocs Formed by the Complexation of Lysozyme with Leonardite Humic Acid
title_short Strength of Flocs Formed by the Complexation of Lysozyme with Leonardite Humic Acid
title_sort strength of flocs formed by the complexation of lysozyme with leonardite humic acid
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463964/
https://www.ncbi.nlm.nih.gov/pubmed/32784682
http://dx.doi.org/10.3390/polym12081770
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