Water solubility of organic pollutants

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

Barac T, S Taghavi, B Borremans, A Provoost, L Oeyen, JV Colpaert, J Vangronsveld, D van der Lelie (2004) Engineered endophytic bacteria improve phytoremediation of water-soluble, volatile, organic pollutants. Nat Biotechnol 22 583-588. 

Okouchi, H., Saegusa, H., Nojima, O. (1992) Prediction of environmental parameters by adsorbability index water solubilities of hydrophobic organic pollutants. Environ. Inti. 18, 249-261. 

Each type of technique can be applied in several modifications. Microbiological degradation processes offer the possibility to purify wastewater streams which contain a wide range of organic pollutants. In contrast, physical/chemical techniques are much more specific. The quality of the purified water regarding residual amounts of soluble organic pollutants, and colloidal and suspended particle pollutants, strongly depends on the type of treatment process and the applied treatment conditions. Very often a combination of different types of treatment techniques is necessary to satisfy the effluent quality required (for example a combination of anaerobic and aerobic treatment). 

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. 

Solvent extraction has many features that make this separation technique applicable for the removal of organic pollutants from wastewater. The organic solutes can be recovered, and there is thus a potential for economic credit to the operation. In comparison with biological treatment, it is not subject to toxicity instabilities. The disadvantage is that, even with solvents having low solubilities in water, solvent losses can be substantial owing to... 

Estimating the Solubilities and the Activity Coefficients of Organic Pollutants in Organic Solvent -Water Mixtures... 

Quantitative distributions of organic pollutants in different phases largely depend on their physical properties the solubility constants in water (K, ) and soil (Koc) and Henry s constant. Figure 2.4 illustrates their distribution in these phases. 

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... 

Oxygen is introduced into water through the water surface. At a constant temperature the solubility of oxygen is directly proportional to the partial pressure above the liquid (Henry s law). Oxygen dissolved in polluted water is used for mineralization of organic pollution, therefore, its concentration usually becomes lower than the equilibrium concentration [40-43]. 

Some of the regulated priority water pollutants concentrate in biological tissues or in the fatty tissue of organisms. Bioaccumulation refers to the fact that the chemical is not broken down by the metabolism of an organism and it tends to remain in the body tissue for a long time (bioconcentrate). The Log of the Bioconcentration Factor (Log BCF) is used to describe the ratio between the concentration of a chemical in biota living in the river (e.g., fish) and the concentration in the surrounding water. The Bioconcentration Factor (BCF) can be estimated from Kow or water solubility of the chemical. 

CDs have a low polarity cavity in which organic compounds of appropriate shape and size can form inclusion complexes. This unique property provides CDs with a capacity to significantly increase the apparent solubility of low polarity organic compounds [81]. As a consequence, they can play a major role in environmental science in terms of solubilization of organic contaminants, enrichment and removal of organic pollutants and heavy metals from soil, water and atmosphere. 

Numerous experimental data exist in the literature on flic solubility of organic solutes, including both drugs and environmental pollutants, in various mixtures of water and cosolvents. Experimental observations are often illustrated by plotting the logarithm of solubility of the solute versus the volume fraction of cosolvent in the solvent mixture. A few examples of solubilization curves are shown in Figure 14.21.2.1, which shows three typical situations for solutes of different hydrophobicity in the mixture of water and ethanol. 

---