Pollutant , water solubility enhancement

Chiou, C.T., Malcolm, R.L., Brinton, T.I., and Kile, D.E. Water solubility enhancement of some organic pollutants and pesticides by dissolved humic and fulvic acids. Environ. Sci. Technol, 20(5) 502-508, 1986. 

Chiou, C. T. Malcolm, R. L. Brinton, T. I. and Kile, D. E. Water Solubility Enhancement of Some Organic Pollutants and Pesticides by Dissolved Humic and Fulvic Acids Environmental Science and Technology, 1986,20 p. 502-508. 

The importance of the colloidal phase in the distribution of water pollutants is a relatively recent issue in the environmental literature [4,105,106]. The phenomenon of colloidal solubility enhancement was detected by workers in several fields and was largely unexplained. The concept was apparently developed and forwarded by working with partitioning behavior of water pollutants in water/ sediment systems. 

The presence of water-soluble macromolecules in solution at submicel-lar concentrations has been reported to enhance the water solubility of hydro-phobic organic chemicals in several instances [19, 106, 113]. The presence of macromolecules in solution can enhance the apparent solubility of solutes by sorptive interactions in the solution phase. The processes by which macromolecules enhance the solubility of pollutants are probably variable as a function of the particular physical and chemical properties of the system. A macromolecule possessing a substantial nonpolar region can sorb a hydrophobic molecule, thereby minimizing the interfacial tension between the solute and the water. 

Application of pollutant chemodynamic models, which neglect the DHS phase, may result in inaccurate estimations of apparent solubility and transport parameters. The impact of a DHS solubility enhancement is most pronounced for the least water-soluble solutes. The affinity of a solute for a DHS is a function of the same properties, which drive a complex organic mixture(s) to sorb onto the stationary solid phase, namely bonding interactions and hydrophobicity. 

Hence, DHS will manifest the greatest solubility enhancement for those pollutants which are the least soluble in water or the most attracted to the solid phase. Organic pollutants, which are soluble in water, are less likely to be sorbed onto the solid or colloidal phase in the absence of specific bonding interactions. 

Humic substances (HS) are polymeric oxidation products that result from the decomposition of plant and animal residues. As a consequence of their colloidal state in natural waters, they play an important role in the transport of organic pollutants. Thus hydrophobic organic pollutants such as polycyclic aromatic hydrocarbons, DDT, and PCBs are known to bind well to humic substances, thereby enhancing the former s water solubility. One important characteristic of... 

The phytoremediation process may be viewed as a symbiotic process between plants and soil microbes that involved in phytoremediation (Lasat, 2002). Plant and bacterial interaction can enhance the effectiveness of phytoremediation technology because plants provide carbon and energy sources or root exudates in the rhizosphere that will support microbial community in the degradation and transformation of soil pollutants (Siciliano and Germida, 1998). In addition, the presence of soil microbes can increase the water solubility or bioavailability of pollutants in soils, which facilitates the uptake of pollutants by plants (Lasat, 2002 Siciliano and Germida, 1998). However, the specificity of the plant-bacteria interactions besides being much intricate is dependent upon soil and the aqueous conditions, which can alter contaminant... 

Enhancement of the Water Solubility of Organic Pollutants Such as Pyrene by Dissolved Organic Matter... 

The addition of water-soluble polymers followed by ultrafiltration, named as polyelectrol)de-enhanced ultrafiltration (PEUF), can be efficiently exploited to remove ionic species from aqueous solutions. This process is based on the use of a polyelectrol)de having an opposite charge to that of the target ions and the formation of macromolecular complexes between pollutant ions and polymer due to electrostatic attractions. These complexes are too large to pass through a UF membrane so they are retained in the retentate streams. Examples of separation of both cationic and anionic metal ions by PEUF have been extensively reported (Christian et al., 1995 Tabatabai et al, 1995a Tangvijitsri et al, 2002). 

However, a defined structure is not always needed. For example, random methy-lation can produce a 3-cyclodextrin derivative in which an average of 1.5 hydroxyl functions per glucose unit is methylated. This pattern enhances the solubility of the cyclodextrin in water, without affecting its ability to form supramolecular inclusion complexes. This has been proven useful in applications such as the extraction of cholesterol or the detoxification of polluted waters [3]. 

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