Binding of cadmium to soil humic acid as a function of carboxyl group content

The binding of Cd(II) to soil humic acid (HA) at pH 6.5 and in 0.1 mol/L KNO3 ionic medium, was studied by potentiometric titration with a cadmium ion selective electrode. The influence of carboxyl groups in cation-humic interactions was investigated by selective blocking of humic acid carboxyl groups with thionyl chloride and methanol. Infrared spectroscopic analysis confirmed that esterification took place. Differences between underivatized and derivatized HA complexation properties are ascribed to carboxyl groups. The Scatchard plots and incremental formation constants were used to obtain values for Cd-binding constants, for both HAs. The derivatization decreased the number of HA complexing sites by approximately 60 %, which correlates with acid-base properties of both HAs, studied by barium hydroxide and calcium acetate exchange methods. The stability constants for binding at the strongest sites (logKINT) was larger for underivatized HA (5.40) than for derivatized HA (4.92), indicating greater stability in the case when carboxyl groups are involved in complexation reaction.

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Thermodynamics of the complexation between salicylaldehyde thiosemicarbazone with Cu2+ ion in methanol +1,4-dioxane binary solutions

Journal of the Serbian Chemical Society ◽

10.2298/jsc130730137b ◽

2014 ◽

Vol 79 (5) ◽

pp. 565-578 ◽

Cited By ~ 1

Author(s):

Rashmidipta Biswas ◽

Dhiraj Brahman ◽

Biswajit Sinha

Keyword(s):

Mixed Solvents ◽

Formation Constants ◽

Molar Conductance ◽

Binary Solvent ◽

Complexation Reaction ◽

Solvent Mixtures ◽

Conductance Data ◽

Different Temperatures ◽

Uv Visible ◽

The Stability

The complexation reaction between salicylaldehyde thiosemicarbazone, abbreviated as STSC, with Cu2+ ion was studied in the binary mixtures of methanol + 1,4-dioxane binary by using UV-Visible spectrophotometric and conductometric methods at different temperatures. The formation constants (Kf) for the 1:1 complex, Cu2+-STSC, were calculated from computer fitting of the absorbance and molar conductance data against various mole ratios (cM:cL or cL:cM) in different binary solvent mixtures. A non-linear correlation was observed for the variation of logKf for the complex against the solvent compositions. Various thermodynamic parameters (?H, ?S and ?G) for the formation of Cu2+-STSC complex were also determined from the temperature dependence of the stability constants (Kf). The results showed that the complexation reaction is affected by the nature and composition of the mixed solvents.

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Study of solvent effect on the stability of water bridge-linked carboxyl groups in humic acid models

Geoderma ◽

10.1016/j.geoderma.2010.12.006 ◽

2011 ◽

Vol 169 ◽

pp. 20-26 ◽

Cited By ~ 22

Author(s):

Adelia J.A. Aquino ◽

Daniel Tunega ◽

Hasan Pašalić ◽

Gabriele E. Schaumann ◽

Georg Haberhauer ◽

...

Keyword(s):

Humic Acid ◽

Solvent Effect ◽

Carboxyl Groups ◽

Water Bridge ◽

The Stability ◽

Stability Of Water

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Characterization of dissolved organic matter (DOM) extracted from soils by hot water percolation (HWP)

Agrokémia és Talajtan ◽

10.1556/agrokem.59.2010.1.12 ◽

2010 ◽

Vol 59 (1) ◽

pp. 99-108 ◽

Cited By ~ 3

Author(s):

M. Takács ◽

Gy. Füleky

Keyword(s):

Organic Matter ◽

Humic Acid ◽

Natural Organic Matter ◽

Extraction Methods ◽

Soil Samples ◽

Hot Water ◽

Soil Extracts ◽

Water Percolation ◽

Soil Humic Acid

The Hot Water Percolation (HWP) technique for preparing soil extracts has several advantages: it is easily carried out, fast, and several parameters can be measured from the same solution. The object of this study was to examine the possible use of HWP extracts for the characterization of soil organic matter. The HPLC-SEC chromatograms, UV-VIS and fluorescence properties of the HWP extracts were studied and the results were compared with those of the International Humic Substances Society (IHSS) Soil Humic Acid (HA), IHSS Soil Fulvic Acid (FA) and IHSS Suwannee Natural Organic Matter (NOM) standards as well as their HA counterparts isolated by traditional extraction methods from the original soil samples. The DOM of the HWP solution is probably a mixture of organic materials, which have some characteristics similar to the Soil FA fractions and NOM. The HWP extracted organic material can be studied and characterized using simple techniques, like UV-VIS and fluorescence spectroscopy.

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Impact of Soil Humic Acid Soil Application and Seaweed Extract Foliar Spray on Growth, Yield, and Fruits Quality of Strawberry Plants Grown under Aswan Conditions

Journal of Soil Sciences and Agricultural Engineering ◽

10.21608/jssae.2017.37496 ◽

2017 ◽

Vol 8 (6) ◽

pp. 307-315

Author(s):

A. Alkharpotly ◽

R. Mohamed ◽

M. Shehata ◽

A. Awad

Keyword(s):

Humic Acid ◽

Acid Soil ◽

Foliar Spray ◽

Growth Yield ◽

Seaweed Extract ◽

Soil Application ◽

Soil Humic Acid

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Structure of the complexes of ethylenediphosphinetetraacetic acid in solution

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19850445 ◽

1985 ◽

Vol 50 (2) ◽

pp. 445-453 ◽

Cited By ~ 2

Author(s):

Jana Podlahová ◽

Josef Šilha ◽

Jaroslav Podlaha

Keyword(s):

Metal Ion ◽

Carboxyl Groups ◽

Complex Solution ◽

Square Planar ◽

Weak Complexes ◽

Carboxylic Groups ◽

Uv Visible ◽

The Stability ◽

Tetrahedral Complexes ◽

Free Carboxyl

Ethylenediphosphinetetraacetic acid is bonded to metal ions in aqueous solutions in four ways, depending on the type of metal ion: 1) through an ionic bond of the carboxylic groups to form weak complexes with a metal:ligand ratio of 1 : 1 (Ca(II), Mn(II), Zn(II), Pb(II), La(III)); 2) through type 1) bond with contributions from weak interaction with the phosphorus (Cd(II)); 3) through coordination of the ligand as a monodentate P-donor with the free carboxyl groups with formation of 2 : 1 and 1 : 1 complexes (Cu(I), Ag(I)); 4) through formation of square planar or, for Hg(II), tetrahedral complexes with a ratio of 1 : 2 with the ligand as a bidentate PP-donor with the free carboxyl groups (Fe(II), Co(II), Ni(II), Pd(II), Pt(II)). On acidification of the complex solution, the first two protons are bonded to the carboxyl groups. The behaviour during further protonation depends on the type of complex: in complexes of types 1) and 2) phosphorus is protonated and the complex dissociates; in complexes of types 3) and 4) the free carboxyl groups are protonated and the phosphorus-metal bond remains intact. The results are based on correlation of the stability constants, UV-visible, infrared, 1H and 31P NMR spectra and magnetic susceptibilities of the complexes in aqueous solution.

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Synthesis and chromatographic characterization of [Tc-99m]technetium-humic acid species

Radiochimica Acta ◽

10.1524/ract.2000.88.2.095 ◽

2000 ◽

Vol 88 (2) ◽

Cited By ~ 9

Author(s):

D. Rößler ◽

K. Franke ◽

R. Süß ◽

E. Becker ◽

H. Kupsch

Keyword(s):

Humic Acid ◽

Stannous Chloride ◽

Gel Permeation Chromatography ◽

Paper Electrophoresis ◽

Gel Permeation ◽

Soil Humic Acid ◽

Chromatographic Characterization ◽

Ph Dependent ◽

Layer Chromatography

A natural moor soil humic acid (HA) was labeled with Tc-99m via reduction of pertechnetate with stannous chloride. The humic acid species obtained were characterized by thin layer chromatography (TLC), gel permeation chromatography (GPC), sequential chromatographic analysis (SCA), paper electrophoresis and micropore filtration. Labeling was found to take place in all ranges of molecular weight. Due to the complex humic acid composition and the formation of hydroxo species the labeling yields strongly depend on the separation conditions, ranging from 42% to 80%. The pH-dependent distribution of mobile and immobile species was determined by SCA for HTcO

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Molecular characterization of an end-residue of humeomics applied to a soil humic acid

RSC Advances ◽

10.1039/c4ra01619j ◽

2014 ◽

Vol 4 (45) ◽

pp. 23658-23665 ◽

Cited By ~ 18

Author(s):

A. Nebbioso ◽

A. Piccolo ◽

M. Lamshöft ◽

M. Spiteller

Keyword(s):

Organic Matter ◽

Humic Acid ◽

Molecular Characterization ◽

Natural Organic Matter ◽

Molecular Composition ◽

Chemical Fractionation ◽

Soil Humic Acid

Humeomics encompasses step-wise chemical fractionation and instrumental determination to fully characterize the heterogeneous molecular composition of natural organic matter.

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A Fluorescence Quenching Analysis of the Binding of Fluoroquinolones to Humic Acid

Applied Spectroscopy ◽

10.1177/0003702817715655 ◽

2017 ◽

Vol 71 (11) ◽

pp. 2512-2518 ◽

Cited By ~ 3

Author(s):

Ryan P. Ferrie ◽

Gregory E. Hewitt ◽

Bruce D. Anderson

Keyword(s):

Humic Acid ◽

Fluorescence Quenching ◽

Water Solubility ◽

Binding Constants ◽

High Water ◽

Static Quenching ◽

Temperature Range ◽

Equilibrium Binding ◽

Quenching Analysis ◽

High Water Solubility

Fluorescence quenching was used to investigate the interaction of six fluoroquinolones with humic acid. Static quenching was observed for the binding of ciprofloxacin, enoxacin, fleroxacin, levofloxacin, norfloxacin, and ofloxacin to humic acid. The equilibrium binding constants were found from Stern–Volmer plots of the data. The quenching experiments were repeated over a temperature range of 25–45 ℃ and van’t Hoff plots were generated. From these linear plots, thermodynamic values were calculated for Δ H, Δ G, and Δ S for each of the fluoroquinolones. The equilibrium binding constants were found to be <1 for all the antibiotics studied. The calculated ΔH values were all negative and ranged from −9.5 to −27.6 kJ/mol. The high water solubility of the antibiotics and low ΔH of binding suggests that the antibiotics will be transported easily through the environment. Finally, whether the fluoroquinolones are in a protonated, deprotonated, or partially protonated state is found to correlate to the strength of binding to humic acid.

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