The role of major functional groups: Multi-evidence from the binding experiments of heavy metals on natural fulvic acids extracted from lake sediments

Li, Hao; Wang, Jinghua; Zhao, Boyi; Gao, Manshu; Shi, Wen‐Jing; Zhou, Haijun; Xie, Zhiyong; Zhou, Bin; Lü, Changwei; He, Jing

doi:10.1016/j.ecoenv.2018.07.038

Cited by 40 publications

(23 citation statements)

References 39 publications

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“…According to Ahmed et al [71], changes in the position and intensity of bands around 1700 and 1600 cm −1 result from coordinate bond formation between lone electron pairs on oxygen atoms and empty d-orbitals in heavy metal. Band usefulness at~1710 cm −1 for the observation of metal complexing processes by humic substances was also demonstrated, among others, by Jerzykiewicz [72] in the studies of mercury complexation and by Li et al [57] during the investigation of the role of functional groups in heavy metals binding by FAs in lake sediments. In our studies, absorption reduction typical of COOH groups was the most intense at pH 3 and the weakest at pH 7, indicating the most intense Zn(II) exchange with protons at pH 3 and the weakest one at pH 7.…”

Section: Ftir Spectra Of Fa-zn(ii) Compoundsmentioning

confidence: 66%

“…Concave-down courses for the Stern-Volmer equation were also For systems with higher pH (5-7), the increase in Zn(II) concentration caused a slight shift of the maxima of A and B areas towards shorter emission waves (shift~5 nm). Li et al [57] observed a similar shift for Cu(II), Pb(II) and Cd(II) binding to FAs by fluorophores at Ex/Em 390 nm/485 nm. They attributed it to a decrease of aromatic rings, reduction of conjugated bonds or conversion of the linear ring system to a non-linear one.…”

Section: Fluorescent Quenching Titration In the Analysis Of Zn(ii) Bimentioning

confidence: 70%

“…It could be explained by the fact that complexation may also take place through dissociated ligands as well as other donor atoms, e.g., nitrogen-containing structures. In the studies on binding Cu, Pb and Cd by FAs obtained from lake sediments, Li et al [57] classified phenolic and carboxyl groups as weaker binding sites as compared to nitrogen-containing groups. They also showed an increase of adsorption capacity of Cu, Pb and Cd ions with the higher pH from 3 to 6 due to deprotonation of functional groups, facilitating the electrostatic attraction of metal.…”

Section: Ftir Spectra Of Fa-zn(ii) Compoundsmentioning

confidence: 99%

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Zinc Binding to Fulvic acids: Assessing the Impact of pH, Metal Concentrations and Chemical Properties of Fulvic Acids on the Mechanism and Stability of Formed Soluble Complexes

Boguta

Sokołowska

2020

Molecules

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The aim of the study was defined as a complementary analysis of molecular interactions between zinc (Zn) and fulvic acids (FAs) at a broad pH range (3–7), different metal concentrations (0–50 mg dm−3) and chemical properties of FAs and their impact on the Zn binding mechanism, stability, and efficiency. The results showed that the complexation reaction prevailed at pH 6 and 7, whereas protons exchange dominated interactions at pH 3. Stability constant of the complexes increased along with pH (logK increased from ~3.8 to 4.2). Complexation was preferred by less-humidified structures of lower molecular mass containing more oxygen groups. The number of fluorophores available for Zn(II) increased from pH 3 to 7 by ~44%. Depending on the pH, complexation involved a bidentate chelate, monodentate and bidentate bridging mode. Zn(II) binding was insufficiently modeled by the classic Stern–Volmer equation and well described by the double logarithmic equation (R > 0.94) as well as by a modified Stern–Volmer formula assuming the existence of available and unavailable fluorophore populations (R > 0.98). The fluorescence ratio of different fluorophores was proposed as an indicator of the binding affinity of various structures. A positive relationship was found between the fraction of accessible fluorophores and Zn(II) binding at pH 7 determined based on proton release (R = 0.91–0.97). The obtained results can find application in controlling the mobility and bioavailability of Zn in different conditions.

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Section: Ftir Spectra Of Fa-zn(ii) Compoundsmentioning

confidence: 66%

Section: Fluorescent Quenching Titration In the Analysis Of Zn(ii) Bimentioning

confidence: 70%

Section: Ftir Spectra Of Fa-zn(ii) Compoundsmentioning

confidence: 99%

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Zinc Binding to Fulvic acids: Assessing the Impact of pH, Metal Concentrations and Chemical Properties of Fulvic Acids on the Mechanism and Stability of Formed Soluble Complexes

Boguta

Sokołowska

2020

Molecules

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“…The size of the FA molecules is smaller than those of HA. Nonetheless, the absorption capacity is 2 -20 times higher than that of HA due to the functional groupscarboxyl, phenolic and carbonyl groups associated with macromolecules and with its aliphatic or organic carbons (Li et al, 2018). The Oxygen content in FA is higher than that in HA and the average molecular weight is 1200.…”

Section: Bioactive Components In Sapropelmentioning

confidence: 97%

Freshwater Sapropel: Biologically Active Components and Methods of Extraction

Kļaviņa

Auce

Pavlovska

et al. 2020

PNS

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Previously, sapropel has been commonly used in agriculture, cosmetology and medicine in its raw form and there has been no generally accepted method or standard for realizing sapropel extract. However, for sapropel usage in medicine, balneology and pharmacy, it is essential to develop quality criteria for raw sapropel and its extracts. This review aims at discussing and summing up different techniques for extracting bioactive compounds from sapropel as well as the possibilities of creating quality criteria. This paper covers existing analytical techniques and methodologies; currently, there are few extraction methods using several extractants for obtaining bioactive components from raw sapropel. Different freshwater sapropel types have been described and characterized. Bioactive components in sapropel have been identified and explained. Humic acids and fulvic acids have been identified as the main substances and their extraction methods have been listed. Solid-liquid, ultrasound assisted and supercritical fluid extraction methods have been pointed out as the most suitable. Additionally, analysis and storage conditions of the extracts have been discussed. There have been found to be no commonly accepted standard methods for sapropel extraction, or for the analysis and characterization of the sapropel extracts. For pharmacological applications, a common approach for the extraction process of active substances from sapropel and the analysis procedures of the extracts need to be established. This review will help equip other researchers with the latest information on this topic.

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“…The reduction of ∆ = v a − v s was attributed to chelation (metal bound to two O atoms) or bridging recombination (one metal bound to each O atom) [42]. After washing the red soil and black soil, three peaks (874, 712, and 618 cm −1 ) appeared in the fingerprint area of HS, mainly the stretching vibration of the C-H or C-O-C bond of the aromatic ring [43]. This may be due to the formation of a new chemical bond after Cd and As combined with the aromatic ring of the HS molecules.…”

Section: Ftir Analysis Of Humic Substance Before and After Washing Comentioning

confidence: 99%

A Soluble Humic Substance for the Simultaneous Removal of Cadmium and Arsenic from Contaminated Soils

Yuan

Wei

et al. 2019

IJERPH

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With abundant oxygen-containing functional groups, a humic substance (HS) has a high potential to remediate soils contaminated by heavy metals. Here, HS was first extracted from a leonardite and analyzed for its chemical compositions and spectroscopic characteristics. Then it was assessed for its ability as a washing agent to remove Cd and As from three types of soils (red soil, black soil, and fluvo-aquic soil) that were spiked with those contaminants (Cd: 40.5–49.1 mg/kg; As: 451–584 mg/kg). The operational washing conditions, including the pH and concentration of the HS, washing time and cycles, and liquid–soil ratio, were assessed for Cd and As removal efficiency. At pH 7, with an HS concentration (3672 mg C/L) higher than its critical micelle concentration and a liquid–soil ratio of 30, a single washing for 6–12 h removed 41.9 mg Cd/kg and 199.3 mg As/kg from red soil, 33.5 mg Cd/kg and 291.5 mg As/kg from black soil, and 30.4 mg Cd/kg and 325.5 mg As/kg from fluvo-aquic soil. The removal of Cd and As from the contaminated soils involved the complexation of Cd and As with the carboxyl and phenolic groups of HS. Outcomes from this research could be used to develop a tailor-made HS washing agent for the remediation of Cd- and As-contaminated soils with different properties.

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The role of major functional groups: Multi-evidence from the binding experiments of heavy metals on natural fulvic acids extracted from lake sediments

Cited by 40 publications

References 39 publications

Zinc Binding to Fulvic acids: Assessing the Impact of pH, Metal Concentrations and Chemical Properties of Fulvic Acids on the Mechanism and Stability of Formed Soluble Complexes

Zinc Binding to Fulvic acids: Assessing the Impact of pH, Metal Concentrations and Chemical Properties of Fulvic Acids on the Mechanism and Stability of Formed Soluble Complexes

Freshwater Sapropel: Biologically Active Components and Methods of Extraction

A Soluble Humic Substance for the Simultaneous Removal of Cadmium and Arsenic from Contaminated Soils

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