Organic contaminants techniques

Theoretical and applied aspects of microwave heating, as well as the advantages of its application are discussed for the individual analytical processes and also for the sample preparation procedures. Special attention is paid to the various preconcentration techniques, in part, sorption and extraction. Improvement of microwave-assisted solution preconcentration is shown on the example of separation of noble metals from matrix components by complexing sorbents. Advantages of microwave-assisted extraction and principles of choice of appropriate solvent are considered for the extraction of organic contaminants from solutions and solid samples by alcohols and room-temperature ionic liquids (RTILs). 

Other techniques to inspect bonding surfaces for contamination have also been proposed, including ultraviolet fluorescence [162], Pulsed ultraviolet light incident on the surface excites fluorescence of organic contamination, which can... 

The most commonly used remediation technique for the recovery of organic contaminants from ground water has been pump- and-treat, which recovers contaminants dissolved in the aqueous phase. In this regard, the application of carbon adsorption has found extensive, but not exclusive use. Vacuum extraction (also called soil venting) has also become popular for removal of volatile organic contaminants from the unsaturated zone in the gaseous phase. Both of these techniques can, in the initial remediation phase, rapidly recover contaminants at concentrations approximately equal to the solubility limit (pump-and-treat), or the maximum gas phase concentration of the contaminant (vacuum extraction). The... 

Y. Zebuelir, C. Naef, D. Broman, K. Eexen, A. Colmsjo and C. Oestman, Sampling techniques and cleanup procedures for some complex environmental samples with respect to PCDDs and PCDPs and other organic contaminants , Chemosphere 19 39-44(1989). 

Wise SA (1993) Standard reference materials for the determination of trace organic constituents in environmental samples. In Barcelo D, ed. Environmental Analysis Techniques, Applications and Quality Assurance, pp 403-446. Elsevier Science Publishers, Amsterdam, The Netherlands. Wise SA, and Schantz MM (1997) Standard reference materials for the determination of trace organic contaminants in environmental samples. In Clement R and Siu M, eds. Reference Materials for Environmental Analysis Making and Using Them, pp 143-186. Lewis Publishers, Boca Raton, FL. 

Bioremediation is not restricted only to biodegradable organic contaminants. New techniques are currently under development for the bioremediation of metal-contaminated sites. Microbial activity can alter the oxidation state of some elements, reducing or increasing their mobility, and this transformation can be used for remediation purposes. 

Factors that affect the accessibility of chemicals to plant roots include hydrophobicity, polarity, sorption properties and solubility. In order to apply phytoremediation techniques to soils polluted by organic contaminants, the contaminant must come into contact with the plant roots and be dissolved... 

Bioremediation is a technique for treating zones of contamination by microbial degradation, which involves altering the environmental conditions to enhance microbial catabolism or cometabolism of organic contaminants, resulting in the breakdown and detoxification of those contaminants.15 According to microbial metabolic activity, bioremediation can be classified into three categories20-21 ... 

The in situ biological treatment technique for organic contaminants is fully discussed in the Chapter 17. An example of a cost estimate for bioremediation is shown in Table 16.5. The data is based on a U.S. EPA study15 of a project performed by Biocraft Laboratories, Waldwick, New Jersey. 

Electroosmotic soil processing is an in situ separation/removal technique for extracting heavy metals and organic contaminants from soils.17 55 89 The fluid between the soil particles moves because a constant, low DC current is applied through electrodes inserted into the soil mass. The electroosmosis (EO) remedial method provides an advantage over conventional pumping techniques for in situ treatment of contaminated fine-grained soils and is more efficient in saturated conditions. 

A wide range of analytical techniques have been developed in order to identify the organic contaminants often present at trace levels in complex environmental samples such as wastewaters. These techniques mainly use gas chromatography (GC) and liquid chromatography (LC). 

Nowicki et al. [51] point out that in the development of a Soxhlet sample preparation technique for sediment samples, the empty paper Soxhlet thimbles contained organic contaminants which adversely affected results. Glass thimbles were tried and found to be satisfactory. The authors detail the identification of organics solvent-extracted from paper and glass Soxhlet thimbles, and discuss the stability for multiple use of the two materials for trace organic sample preparation. 

Anastos, G., Corbin, M. H., and Coia, M. F., 1986, In Situ Air Stripping A New Technique for Removing Volatile Organic Contaminations from Soils In Proceedings of Superfund, 86. Hazardous Materials Control Research Institute, Silver Spring, MD. 

Photocatalysis over oxide semiconductors has been proposed as an effective, mild and environmental friendly technique for the abatement of (refractory) organic contaminants with oxygen as electron acceptor [15]. In this case the reaction is normally exoergonic, as the overall reaction (mineralization) is organics + yC>2 = xCC>2 + ZH2O. 

Huckins, J.N. Petty, J.D. Lebo, J.A. Orazio, C.E. Prest, H.E Tillitt, D.E. Ellis, G.S. Johnson, B.T. Manuweera, G.K. 1996, Semipermeable Membrane Devices (SPMDs) for the Concentration and Assessment of Bioavailable Organic Contaminants in Aquatic Environments. In Techniques in Aquatic Toxicology, Ostrander, G.K., Ed. CRC Press Boca Raton, FL pp. 625-655. 

The effect of solution chemistry on the speciation of the organic contaminant 1-naphtol (1-hydroxynaphthalene) and its complexatiom with humic acid is reported by Karthikeyan and Chorover (2000). The complexation of 1-naphtol with humic acid (HA) was studied during seven days of contact, as a function of pH (4 to 11), ionic strength (0.001 and 0.1 M LiCl), and dissolved concentration (DO of 0 and 8 mg L ) using fluorescence, UV absorbance, and equilibrium dialysis techniques. In a LiCl solution, even in the absence of HA, oxidative transformation of 1-naphtol mediated by was observed. In addition, the presence of humic acid in solution, in the absence of DO, was found to promote 1-naphtol oxidation. These reactions are affected by the solution chemistry (pH, ionic strength, and cation composition). 

Coleman WE, Melton RG, Slater RW, et al. 1981. Determination of organic contaminants by the Grob closed-loop-stripping technique. J Am Water Works Assoc71 119-125. 

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