Humic Substances. Structural Aspects, and Photophysical, Photochemical and Free Radical Characteristics

Choudhry, Ghulam Ghaus

doi:10.1007/978-3-540-38829-6_1

Cited by 42 publications

(53 citation statements)

References 44 publications

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“…Chemical treatment for purifi cation causes structural changes. Over the past few years, many models of the structure of HS have been proposed [1][2][3][4][5][6]. The structure of these exceptionally complex compounds ( Fig.…”

Section: Impact Of Humic Acids On Eyl Liposome Membranes: Esr Methodsmentioning

confidence: 99%

“…The chemistry of HS is infl uenced by functional group heterogeneity and variations in molecular size. The HA and FA, the most common fractions in which the HS are fractionated, have been shown to contain many oxygen-containing groups: carboxyls, hydroxyls, and carbonyls [3]. The molecular weights of HS vary from a few hundred to several millions and among others decides on these mobility.…”

Section: Impact Of Humic Acids On Eyl Liposome Membranes: Esr Methodsmentioning

confidence: 99%

“…The habitat in which HS are formed has a direct impact on their internal structure, known as the degree of aromaticity and alifaticity, which in turn determines their mobility and complexation with xenobiotics and consequently their impact on the biosphere [7]. Some research showed [3,6,8] that HS extracted from natural sources could be contaminated by different metal ions. Therefore, ESR spectra, analyzed by wide sweep range could be showed it.…”

Section: Impact Of Humic Acids On Eyl Liposome Membranes: Esr Methodsmentioning

confidence: 99%

“…According to Schnitzer [1], it is the main topic of research on HS. In light of previous studies [1][2][3], it is believed that the humic acid (HA) molecule is a polymer composed of aromatic rings connected by -O-, -NH-, -(CH 2 )n, and containing various functional groups (carboxyl, phenol, methoxy, methyl, etc.). In the structural molecules of HS, there are differences in their molecular weights and in the total content of functional groups.…”

Section: Introductionmentioning

confidence: 99%

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Impact of humic acids on EYL liposome membranes: ESR method

et al. 2015

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Abstract. In this paper, the effects of model (commercial) and natural (extracted from peat) humic substances on the membrane of liposomes formed with egg yolk lecithin (EYL) are presented. In our research, mass concentrations of fulvic and humic acids were used, which in relation to lecithin varied from 0% to 13%. To study membrane fl uidity, electron spin resonance (EPR) was used with two spin probes, penetrating various regions of the lipid bilayer. The effects of model and natural humic substances (humic acids -HAs and fulvic acidsFAs) on the lipid membrane in different regions were researched: the lipid-water interphase, and in the middle of the lipid bilayer. It was shown that FA and HA impact the fl uidity of liposome membranes in different ways. Increased mass concentrations of HAs decreased membrane fl uidity in both acids: extracted from peat and the model. However, increased mass concentration of FAs extracted from peat, decreased membrane fl uidity in the surface region, at the same time stiffening the central part of the bilayer. Increasing the concentration of FAs extracted from peat had the opposite effect when compared to model FA. This effect may be related to the complexation of xenobiotics present in the soil environment and their impact on biological membranes.

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Section: Impact Of Humic Acids On Eyl Liposome Membranes: Esr Methodsmentioning

confidence: 99%

Section: Impact Of Humic Acids On Eyl Liposome Membranes: Esr Methodsmentioning

confidence: 99%

Section: Impact Of Humic Acids On Eyl Liposome Membranes: Esr Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact of humic acids on EYL liposome membranes: ESR method

et al. 2015

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“…[7][8][9] HAs present relatively high molecular mass polyelectrolytes containing aromatic, aliphatic and heterocyclic subunits. 10 Their chemical structure is less known due to the origin and the natural conditions prevailing during their formation. 11 The degree of ionization of these macromolecules is governed by the amount of ionized phenolic and carboxylic groups of HAs, which is a function of solution pH.…”

Section: Introductionmentioning

confidence: 99%

Capillary electrophoresis (CE): a powerful tool to characterize humic acid (HA)

Moraes¹,

Rezende²

2008

J. Braz. Chem. Soc.

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Neste estudo, avaliou-se a possibilidade de eliminação das etapas de purificação envolvidas na caracterização de HA. HA de diferentes fontes foram analisados por CZE apresentando diferentes eletroferogramas. Essas diferenças observadas mostram que a caracterização do HA por CZE depende da carga e do tamanho do HA. Os resultados apresentados neste trabalho sugerem que não é necessária a purificação da amostra para a caracterização de HA por CZE. Baseados nos resultados, a CZE mostrou-se uma ferramenta promissora para caracterização de HA de diferentes origens sem a etapa de purificação da amostra.The present study evaluates the possibility of eliminating the purification steps involved in the characterization of HA by capillary zone electrophoresis (CZE). The HAs of various sources were analyzed, showing different electropherograms by CZE, which depend on the charge and size of HA. The data suggest that the purification of the sample is not necessary to characterize HAs. Based on the results, CZE showed to be a promising tool to characterize HA of different origins without the purification step of the sample. Keywords: humic acid, characterization, capillary zone electrophoresis IntroductionHumic substances (HS) have an important role in the environment. They are related to the fertility of the soils, contributing to the increasing the harvest production. 1,2 In soil, HS are implicated in water-holding capacity, pH buffering, ion exchange, binding of metal ions and hydrophobic compounds. [3][4][5][6] These substances are classified into three groups, humic acids (HAs), fulvic acids (FAs) and humins, on the basis of their solubility in acidic and basic solutions. [7][8][9] HAs present relatively high molecular mass polyelectrolytes containing aromatic, aliphatic and heterocyclic subunits.10 Their chemical structure is less known due to the origin and the natural conditions prevailing during their formation. 11 The degree of ionization of these macromolecules is governed by the amount of ionized phenolic and carboxylic groups of HAs, which is a function of solution pH. 12-14As a modern analytical technique, capillary electrophoresis (CE) has become an attractive method for the characterization of molecules with high structural complexity and wide range of molecular weights, such as HA. [15][16][17][18] The CE, as a method of characterizing a variety of HS, is suitable due to its polyelectrolyte properties, reflecting its charge-to-mass ratio. [19][20][21][22][23][24][25][26] The characterization of humic compounds provides important information for the evaluation of their capacity of interaction with metal ions and different classes of organic compounds as pesticides. 25Some valuable features of this analytical technique are short analysis time, selectivity for the analytes, simple analytical procedure, and micro-quantity consumption of samples. In CZE, the introduction of samples is carried out at the anode, while the detection is realized at the cathode. Ionic species are separated based on their charge and si...

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Batch and Continuous Design of a Full‐Scale Treatment Facility for Removing Dissolved Natural Organic Matter

Sarı

Oztas

Keskınkan

et al. 2020

CLEAN Soil Air Water

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Batch and continuous flow adsorption experiments are carried out and the design of a full‐scale facility for removing dissolved natural organic matter (DNOM) from Catalan Lakewater is demonstrated. The adsorption efficiency is proportional to the temperature and the amount of adsorbent unlike pH increase. The highest DNOM removal rate is obtained at 35 °C, pH 4, and an adsorbent amount of 0.8 g L−1. Optimum contact time for batch studies is 60 min at equilibrium. Correlation constants (r) of Langmuir and Freundlich isotherms are 0.8905 and 0.9739, respectively. Based on the Freundlich isotherm, the highest adsorption capacity (qmax) obtained is 2.44 and 6.01 mg DNOM/g granulated activated carbon (GAC) for raw and enriched water, respectively. Consequently, the effects of adsorbent amount, bed depth, empty bed contact time, and organic loading on removal performance are investigated in the rapid small‐scale column test (RSSCT) columns. The targeted effluent concentration of 1 mg DNOM/L can easily be achieved in the columns. At the design capacity of the facility, 15 adsorption columns with dimensions of 7 m height, 4.33 m diameter, and 22 days of operation cycle are required to remove DNOM from raw water.

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Humic Substances. Structural Aspects, and Photophysical, Photochemical and Free Radical Characteristics

Cited by 42 publications

References 44 publications

Impact of humic acids on EYL liposome membranes: ESR method

Impact of humic acids on EYL liposome membranes: ESR method

Capillary electrophoresis (CE): a powerful tool to characterize humic acid (HA)

Batch and Continuous Design of a Full‐Scale Treatment Facility for Removing Dissolved Natural Organic Matter

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