Fulvic substances

Buffle, J. and Cominoli, A. (1981). Voltammetric study of humic and fulvic substances. Part IV. Behaviour of fulvic substances at the mercury-water interface, J. Electroanal. Chem., 121, 273-299. 

Sorption of pharmaceuticals onto the surface of particulate matter or their distribution between two phases (water and either sludge, sediment or soil) depends on many factors, the most important being liquid phase pH and redox potential, the stereochemical structure and chemical nature of both the pharmaceutical compound and the sorbent, the lipophilicity of the sorbed molecules (excellent sorption at log Kov > 4, low sorption at log < 2.4), the sludge-water distribution coefficient Kd Kd > 2 L g SS good sorption, < 0.3 L g SS low sorption), the extent of neutral and ioiuc species present in the wastewater and the characteristics of the suspended particles. Moreover, the presence of humic and fulvic substances may alter the surface properties of the sludge, as well as the number of sites available for sorption and reactions, thereby enhancing or suppressing sorption of PhCs [38, 55, 61]. 

Figure 8.26 (A) Functional groups of humic substances. (B) Complexing schemes for fulvic substances. Reprinted from Stevenson (1983), with kind permission of Theophrastus Publishing and Proprietary Co.

Besides humic and fulvic substances in surface waters and soils, organic compounds occur in a variety of geochemical environments. Their role is determinant in the following processes. 

Buffle, 3., 1980. A critical comparison of studies of complex formation between copper (II) and fulvic substances of natural waters. Anal. Chim. Acta, 118 29-44. 

Indirect photolysis mechanisms involve the excitation of an additional compound called a photosensitizer (PS), which in its excited state can directly oxidize the pollutant of interest. This type of mechanism was investigated by Faust and Hoigne [82] using fulvic substances as photosensitizers of phenols in natural waters. These latter mechanisms correspond to the indirect photolysis of M. In fact, Faust and Hoigne [82] reported that there are four possible routes of the excited photosensitizing action ... 

UV/H202 oxidation of VOCs has also been studied in detail and several studies reported kinetic models to predict the efficiency of the process. For example, Liao and Gurol [75], Glaze et al. [113], De Laat et al. [155] and Crittenden et al. [74] studied the UV/H202 oxidation of VOCs such as n-chlorobutane, 1,2-dibromo-3-chloropropane and tri- and tetra-chloroethanes in batch photoreactors with low-pressure mercury vapor lamps. Effects of pH, concentration of hydrogen peroxide, UV intensity and the presence of carbonates or fulvic substances were variables studied. 

Sakkas VA, Lambropoulou DA, AlbanisTA. Photochemical degradation study of irgarol 1051 in natural waters influence of humic and fulvic substances on the reaction. J Photochem Photobiol A Chem 2002 147 135-41. 

Humic substances are ubiquitous in the environment, occurring in all soils, waters, and sediments of the ecosphere. Humic substances arise from the decomposition of plant and animal tissues yet are more stable than their precursors. Their size, molecular weight, elemental composition, structure, and the number and position of functional groups vary, depending on the origin and age of the material. Humic and fulvic substances have been studied extensively for more than 200 years however, much remains unknown regarding their structure and properties. 

The presence of humic and fulvic acids in surface waters and groundwaters will have a significant influence on the transport and fate of metals, radionuclides, and organic contaminants in the environment. These natural organic acids can either transport or immobilize contaminants, depending on the environmental conditions. Humic and fulvic substances can also retard or enhance the photochemical decomposition of pesticides or toxic organics. Therefore, to be sucessfiil any remediation strategies must consider the effects of humic materials. If properly understood, this behavior can be used to manipulate pollutant solubilization and facilitate containment or cleanup of contaminated sites. 

Determination of the amounts of humic and fulvic substances in peats and mucks of various botanical origin and mineral content to establish whether advances in humification preferentially favor the increase of one or the other would therefore be achieved only when proper methods of extraction and fractionation are established and followed in full cognizance of the problems discussed in this and other chapters. The fractionation of humin from min-... 

Buffle, J., and Greter, F. L. (1979). Voltammetiic study of humic and fulvic substances, II Mechanism of reaction of the Pb-fulvic complexes on the mercury electrode. J. Electroaned. Chem. 101, 231-251. 

Buffle, J., Deladoey, P., Greter, F. L., and Haerdi, W. (1980). Study of the complex formation of copper(II) by humic and fulvic substances. Anal. Chim. Acta 116, 255-274. 

Dalang, F-, J. Buffle, and W. Haerdi (1984), Study of the Influence of Fulvic Substances on the Adsorption of Copper(II) Ions at the Kaolinite Surface, Environ. Sci. TechnoL 18, 135-141. 

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