Chemical destruction method

In R ef 1 are described recommended chemical destruction methods for BkPdr, LA,... 

A chemical destruction method that has been used for the treatment of PCBs in contaminated dielectric liquids or soil is based on the reaction of a polyethylene glycol/potassium hydroxide mixture with PCBs (De Filippis et al. 1997). This method can be used successfully for the destruction of higher chlorinated PCBs with an efficiency of >99%, but was found to be unsuitable for the treatment of di- and trichlorobiphenyls due to low destruction efficiencies (Sabata et al. 1993). Irradiation of PCBs in isooctane and transformer oil by y-radiation resulted in degradation of PCBs to less chlorinated PCBs and PCB-solvent adducts (Arbon et al. 1996). Supercritical fluid technology has shown promise as a method for extraction of PCBs from soils, coupled with supercritical water oxidation of the extracted PCBs (Tavlarides 1993,1998a). Hofelt and Shea (1997) demonstrated the use of semipermeable membrane devices to accumulate PCBs from New Bedford Harbor, Massachusetts water. Another method showing... 

Catalytic Dehydrohalogenation A Chemical Destruction Method for Halogenated Organics... 

Oxides (Ln Oj), fluorides (LnF ), sulfides (Ln S, LnS), sulfofluorides (LnSF) of lanthanides are bases of different functional materials. Analytical control of such materials must include non-destructive methods for the identification of compound s chemical forms and quantitative detenuination methods which does not require analytical standards. The main difficulties of this analysis by chemical methods are that it is necessary to transform weakly soluble samples in solution. 

Dinkelaker B., Hahn G., Romheld V., Wolf G.A, Marschner H. Non-destructive methods for demonstrating chemical changes in the rhizosphere 1. Description of method. Plant Soil 1993 155/156 67-70. 

Spectroscopic techniques such as electron spin resonance (ESR) offer the possibility to "probe" the chemical environment of the interlayer regions. With the ESR technique, an appropriate paramagnetic ion or molecule is allowed to penetrate the interlayer, and chemical information is deduced from the ESR spectrum. Transition metal ions, such as Cu2+, and nitroxide radical cations, such as TEMPAMINE (4-amino-2,2,6,6-tetramethylpiperidine N-oxide) have been used as probes in this manner (6-14). Since ESR is a sensitive and non-destructive method, investigations of small quantities of cations on layer silicate clays at various stages... 

Chemical analysis is the proof of many innovations the evolution of technologies has led to the development of high-performance instruments allowing new possibilities, notably hyphenated methods and non-destructive methods. Non-destructive tests can be conducted on very small samples that do not necessitate extensive sample preparation. Users can finally acquire instruments that meet the quality and precision requirements necessary to obtain certification. This latter requirement is an important if not a sufficient condition to officially recognise the quality of results produced by a laboratory. Certification procedures are enforced by a number of testing bodies all over the world. 

Chemical Destruction of Explosives These methods rely upon chem reactions, which to be completed require time and full contact of the expl with the reagent, usually in soln. Chem methods should not be used in attempts to destroy expls in large quantities or when any of the expl items are enclosed or pressed into components such as detonators. Chem destruction methods are suitable for use in labs for quantities of expls not greater than ca 25g... 

Decolorization. This is the process of making dark substances lighter in color and opaque substances more nearly white or transparent by either chemical destruction, or removing of coloring impurities by adsorption. Decolorization must be performed without damaging effects upon treated material. In the chem decolorization method, known as bleaching, the material is treated with an oxidizing or... 

Use of inductively coupled plasma-mass spectrometry (1CP-MS) coupled to a laser-ablation sample introduction system (LA-ICP-MS) as a minimally destructive method for chemical characterization of archaeological materials has gained favor during the past few years. Although still a relatively new analytical technique in archaeology, LA-ICP-MS has been demonstrated to be a productive avenue of research for chemical characterization of obsidian, chert, pottery, painted and glazed surfaces, and human bone and teeth. Archaeological applications of LA-ICP-MS and comparisons with other analytical methods are described. 

Natural ceramic raw materials have the disadvantage that they are not soluble in water and consequently unsuitable for wet chemical analysis. That is why they are first destructed in the laboratory. Destruction means that a substance or a mixture of substances is heated together with a substance or a mixture of substances and as a result the component to be destructed is largely separated into ions and consequently dissolves in water. The destruction method and the substances are specific for the substance undergoing the destruction. Different methods applied to the same substance lead to different results. 

Separation techniques are not considered in this chapter and attention will be devoted almost entirely to chemical identification techniques. The methods which are discussed here are summarised in Table 3.1, which also lists some of the main separation techniques that are available. Emphasis will be placed on the various types of spectroscopy, since this chapter is concerned with non-destructive methods for the determination of speciation. 

Direct methods for determining the combinational form of an element or its oxidation state include infrared absorption spectrometry, X-ray diffraction and, more recently, electron paramagnetic resonance - nuclear magnetic resonance -and Mossbauer spectrometry. With such techniques the combinational forms of major elements in soil components such as clay minerals, iron, manganese and aluminium oxyhydroxides and humic materials and the chemical structures of these soil components have been elucidated over the past 50 years. These direct, mainly non-destructive, methods for speciation are dealt with in some detail in Chapter 3 and are not further discussed here. 

Destructive methods involve mechanical and chemical erosion (low resolution) and ion sputtering, which is by far the most widely used of any of the depth profiling techniques. Surface atoms are progressively removed by ion bombardment and are analysed by SIMS. Alternatively, the residual surface may be analysed, generally by AES. The method is universally applicable and in principle is capable of near-atomic depth resolution. In practice, conversion of the observed signal, as a function of time, into concentration as a function of depth may not be easy for a complex system. It should be noted that the information obtained is reliable for the first layer, but for deeper layers the possibility of scrambling of the atomic layers... 

Charcoal and Other Chemicals. Production of charcoal and tars by destructive distillation is the oldest of all chemical woodprocessing methods. Charcoal probably was first discovered when the black material left over from a previous fire burned with intense... 

Destructive method (radiochemical neutron activation analysis, RNAA) based on the chemical separation of radioelements into fractions, each of which contains some radionuclides [17-20]. 

---