Fulvic acids, adsorption

Rnauer, K. and Buffle, J. (2001). Adsorption of fulvic acid on algal surfaces and its effect on carbon uptake, J. Phycol., 37, 47-51. 

The adsorption of humic and fulvic acids on surfaces can be interpreted along the scheme of Fig. 4.9c,d. Because of hydrophobic interaction humic and fulvic acids tend to accumulate at the solid-water interface. At the same time the adsorption is influenced by coordinative interaction, e.g., schematically,... 

It is necessary to remind ourselves, that the adsorption of humic acids or fulvic acids correspond to the adsorption of a mixture of adsorbates. Adsorption equations derived for the adsorption of a single adsorbate (Langmuir, Frumkin or Gibbs Equation) cannot be used for mechanistic interpretation of the data even if these data can be fitted to such equations (Tomaic and Zutic, 1988). 

LDHs are also promising materials as sorbents for anionic organic contaminants via both ion-exchange and reconstruction reactions. There have been a large number of reports of the use of LDHs for removal of species such as aromatic carboxylic acids, phenols, pesticides, and humic or fulvic acids. Recently, Cardoso et al. [152] found that the sorption process of terephthalate anions from aqueous solutions by calcined Mg/Al - CO3 LDHs takes place by reconstruction of the LDHs and involves the intercalation and adsorption of terephthalate anions. Calcined Mg/Al - CO3 LDHs were found to be capable of removing 40 to 85 % of the benzoate from solutions in the concentration... 

Recall from Chapter 23.2.4 that humic substances are isolated from seawater by adsorption on a hydrophobic resin followed by elution using solvents of varying pH. The desorbed compounds are fractionated into two classes, humic acids fulvic acids based on their solubility behavior. A model structure for a humic acid is illustrated in Figure 23.10a in which fragments of biomolecules, such as sugars, oligosaccharides. 

Using the aforementioned methodology, the electrode reaction of Mo(VI) has been studied in the presence of phenanthrohne and an excess of fulvic acids [105]. Both ligands exhibit a synergetic effect toward adsorption of the mixed complex of... 

Khan, S.U. Adsorption of 2,4-D from aqueous solution by fulvic acid-clay complex. Environ. Sci. Technol, 8(3) 236-238, 1974. 

In another study, maximum adsorption of fulvic acid from a podzol B horizon by goethite was found to lie at ca. 0.6 0.3 and 0.05 mg m at pH 4 7 and 10, respectively and this was successfully described with the CD-MUSIC model (Films et al.,... 

In view of its importance, reductive dissolution of Fe oxides has been widely studied. Reductants investigated include dithionite, thioglycolic acid, thiocyanate, hydrazine, ascorbic acid, hydroquinone, H2S, H2, Fe ", tris (picolinato) V", fulvic acid, fructose, sucrose and biomass/bacteria (Tab. 12.3). Under the appropriate conditions, reductive dissolution may also be effected photochemically. As with protonation, the extent of reduction may be strongly influenced by ligand and proton adsorption on the oxide surface. 

Wang, H.D. White, G.N. Turner, F.T. Dixon, J.B. (1993) Ferrihydrite, lepidocrocite, and goethite in coatings from East Texas vertic soils. Soil Sci. Soc. Am. J. 57 1381-1386 Wang, L. Chin,Y.-P. Taina, S.J. (1997) Adsorption of (poly) maleic acid and an aquatic fulvic acid by goethite. Geochim. Cosmochim. Acta 61 5313-5323... 

DOM is derived from autochthonous sources such as phytoplankton and photosynthetic bacteria (16) at Big Soda Lake near Fallon, Nevada. This lake is alkaline (pH 9.7) and chemically stratified. It contains DOC concentrations as high as 60 mg/L and dissolved salt concentrations as high as 88,000 mg/ L (17). The DOM in this lake is colorless. The fulvic acid fraction was isolated by adsorption chromatography (Amberlite XAD-8 resin) (18) and by zeo-trophic distillation of water from N,N-dimethylformamide (19). Average molecular model synthesis was achieved in a manner similar to that used for fulvic acid from the Suwannee River. The characterization data are presented in Table I and the structural model is presented in Structure 2. 

Dissolved organic compounds may compete with arsenic for adsorption and ion-exchange sites on a variety of sorbents (Stollenwerk, 2003), 89. Specifically, fulvic acid is known to interfere with As(V)... 

Simeoni, M.A., Batts, B.D. and McRae, C. (2003) Effect of groundwater fulvic acid on the adsorption of arsenate by ferrihydrite and gibbsite. Applied Geochemistry, 18(10), 1507-15. 

Parfitt, R. L., A. R. Fraser, and V. C. Farmer. 1977. Adsorption on hydrous oxides. HI. Fulvic acid and humic acid on goethite, gibbsite and imogolite. Journal of Soil Science 28 289—296. 

Schultess, C. P., and C. P. Huang. 1991. Humic and fulvic acid adsorption by silicon and aluminum oxide surfaces on clay minerals. Soil Science Society of America Journal 5 5 34—42. 

Zhou, Q. H., P. A. Maurice, and S. E. Cabaniss. 2001. Size fractionation upon adsorption of fulvic acid on goethite Equilibrium and kinetic studies. Geochimica et Cosmochimica Acta 65 803-812. 

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