A unified physicochemical description of the protonation and metal ion complexation equilibria of natural organic acids (humic and fulvic acids). 3. Influence of polyelectrolyte properties and functional heterogeneity on the copper ion binding equilibria in an Armadale Horizons Bh fulvic acid sample

1986 ◽  
Vol 20 (4) ◽  
pp. 367-376 ◽  
Author(s):  
J. Ephraim ◽  
J. A. Marinsky
Keyword(s):  
Organic Acids ◽  
Fulvic Acid ◽  
Metal Ion ◽  
Copper Ion ◽  
Fulvic Acids ◽  
Ion Binding ◽  
Functional Heterogeneity ◽  
Humic And Fulvic Acids ◽  
Acid Sample ◽  
Physicochemical Description

scholarly journals Development of methods for the separation and characterization of natural organic matter in dam water

2014 ◽  
Author(s):  
◽  
Pinkie Sobantu
Keyword(s):  
Molecular Weight ◽  
Humic Acid ◽  
Fulvic Acid ◽  
Humic Substances ◽  
Water Samples ◽  
Fulvic Acids ◽  
Hydroxyl Groups ◽  
Humic And Fulvic Acids ◽  
Vaal Dam

This project arose out the need for a simple method to analyse NOM on a routine basis. Water samples were obtained from the Vaal dam, which is one of the dams used by a hydroelectric power station. Analysis was preceded by separation of NOM into the humic and non-humic portions. The humic portion was separated into two fractions by employing a non-ionic resin (DAX-8) to separate humic acid from fulvic acid. High performance size exclusion chromatography (HPSEC), equipped with an Ultraviolet( UV) detector and an Evaporative Light Scattering (ELS) detector connected in series, was used to obtain molecular weight distribution information and the concentration levels of the two acids. Mixed standards of polyethylene oxide/glycol were employed to calibrate the selected column. Suwanee River humic acid standard was used as a certified reference material. The molecular weight distributions (MWDs) of the isolated fractions of humic and fulvic acids were determined with ELSD detection as weight-average (Mw), number-average (Mn) and polydispersity (ρ) of individual NOM fractions. The Mw/Mn ratio was found to be less than 1.5 in all the fractions, indicating that they have a low and narrow size fraction. An increase in Mn and Mw values, with increasing wavelength for all three humic substances (HS) examined was observed. The HS, isolated from the dam water, was found to be about the same molecular weight as the International Humic Acid Standard (IIHSS). For the fulvic acid standard, the molecular weight was estimated to be around 7500 Da. Characterization of NOM was done to assist in the identification of the species present in the water. FTIR-ATR was used to as a characterization tool to identify the functional groups in the structure of the humic and fulvic acid respectively present in the Vaal Dam. Analysis of the infrared (IR) spectra indicated that the humic acids of the Vaal dam have phenolic hydroxyl groups, hydroxyl groups, conjugated double bond of aromatic family (C=C), and free carboxyl groups. The isolation method has proved to be applicable and reliable for dam water samples and showed to successfully separate the humic substances from water and further separate the humic substances into its hydrophobic acids, namely, humic and fulvic acids. It can be concluded that the Eskom Vaal dam composes of humic substance which shows that the technique alone gives a very good indication of the characteristics of water. The HPSEC method used, equipped with UV and ELSD was able to identify the molecular weight range of NOM present in source water as it confirmed that the Eskom Vaal dam contains humic substances as humic acid and fulvic acid and these pose a health concern as they can form disinfectant byproducts in the course of water treatment with chemicals. FTIR characterization was successful as important functional groups were clearly assigned. Lastly, the use of the TOC and DOC values to calculate SUVA was also a good tool to indicate the organic content in water. It is recommended to use larger amounts of water must be processed to obtain useful quantities of the humic and fulvic acid fractions.

Effects of Water Quality on Microporous Filter Methods for Enteric Virus Concentration

1985 ◽  
Vol 17 (4-5) ◽  
pp. 665-679 ◽  
Author(s):  
M. D. Sobsey ◽  
T. Cromeans ◽  
A. R. Hickey ◽  
J. S. Glass
Keyword(s):  
Fulvic Acid ◽  
Bentonite Clay ◽  
Enteric Virus ◽  
Fulvic Acids ◽  
Virus Concentration ◽  
Humic And Fulvic Acids ◽  
Virus Adsorption ◽  
Filter Methods ◽  
High Concentrations ◽  
Virus Recovery

Model enteric viruses were concentrated from seeded samples of raw, finished and granular activated carbon (GAC)-treated waters and from GAC-treated waters supplemented with humic or fulvic acid or bentonite clay particles by adsorption to electropositive (Virosorb 1MDS) filters at pH 7.5 or electronegative (Filterite) filters at pH 3.5 with and without 5 mM added MgCl2, followed by elution with 0.3% beef extract in 50 mM glycine at pH 9.5. Natural particulates in raw and finished waters had little effect on virus concentration efficiencies. Soluble organic compounds reduced virus adsorption efficiencies from both raw and finished waters compared to GAC-treated water, but the extent of interference varied with virus type and adsorption conditions. Humic and fulvic acids caused appreciable reductions in poliovirus adsorption and recovery efficiencies with both types of filters. Fulvic acid caused greater reductions in virus recovery with Virosorb 1MDS filters than with Filterite filters. Fulvic acid interference with virus recovery by Filterite filters was overcome by the presence of 5 mM MgCl2. Although humic acid reduced virus recoveries by both types of filters, its greatest effect was on virus elution and recovery from Filterite filters. Bentonite clay enhanced poliovirus retention by both filter types as much as 8-fold. However, the presence of clay often interfered with elution of retained viruses from both filter types. Under some conditions, overall virus recoveries were considerably lower from water with clay than from clay-free control water. The results of this study suggest that high concentrations of soluble organic matter such as humic and fulvic acids and suspended solids such as bentonite clay may interfere somewhat with virus recovery by filter adsorption-elution methods.

Computational scheme for the prediction of metal ion binding by a soil fulvic acid

1995 ◽  
Vol 302 (2-3) ◽  
pp. 309-322 ◽  
Author(s):  
J.A. Marinsky ◽  
M.M. Reddy ◽  
J.H. Ephraim ◽  
A.S. Mathuthu
Keyword(s):  
Fulvic Acid ◽  
Metal Ion ◽  
Computational Scheme ◽  
Ion Binding ◽  
Metal Ion Binding

Uranium(VI) complexation with citric, humic and fulvic acids

2000 ◽  
Vol 88 (6) ◽  
Author(s):  
J.J. Lenhart ◽  
S.E. Cabaniss ◽  
P. MacCarthy ◽  
Bruce D. Honeyman
Keyword(s):  
Humic Acid ◽  
Fulvic Acid ◽  
Ph Dependence ◽  
Fulvic Acids ◽  
Humic And Fulvic Acids ◽  
Binding Model ◽  
High Affinity ◽  
Ph Values ◽  
Mononuclear Complexes ◽  
Large Size

The binding of uranium(VI) by Suwannee River humic and fulvic acids was studied at pH values of 4.0 and 5.0 in 0.10 M NaClOBoth humic and fulvic acids were demonstrated to strongly bind U(VI), with humic acid forming slightly stronger complexes and exhibiting greater pH dependence. Analyses of the data for the humic and fulvic acid systems using the Schubert´s equation previously applied to the citrate system result in an apparent nonintegral number of ligands binding the uranyl ion. Schubert´s method is only appropriate for interpreting mononuclear complexes with integral moles of binding ligands. Thus, a more elaborate binding model was required and the data were interpreted assuming either: (1) a mixture of 1:1 and 1:2 uranyl-ligand complexes or (2) a limited number of high affinity sites forming a 1:1 complex. While both of these modeling approaches are shown to provide excellent fits to the data, the second is deemed more appropriate given the large size of humic and fulvic acid molecules as well as previous results obtained with other metal cations, such as Cu(II).

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