Thermal desorption applicability

Identification of the Volatile and Semi-Volatile Organics in Chewing Gums by Direct Thermal Desorption. John J. Manura, Scientific Instrument Services, Inc., Short Path Thermal Desorption—Application Note No. 12 — October 1992, http //www.sisweb.com/referenc/applnote/ap12-a.htm... 

Cost information for various thermal desorption applications is summarized in Table 1. 

Lopez, R, Batlle, R., Neiin, C., Cacho, J., and Ferreira, V. (2007). Use of new generation poly(styrene-divinylbenzene) resins for gas-phase trapping-thermal desorption - Application to the retention of seven volatile organic compounds. J. Chromatogr. A., 1139, 36 4. 

Perkin Elmer, Thermal Desorption Application Notes Nos 1-30. Perkin Elmer Ltd, Bea-consfield. 

Figure 239 Five micro-furnace pyrolysis tubes for different pyrolysis and thermal desorption applications. (Frontier Laboratories Ltd., Japan.) (a) Liquid sampler for direct liquid sample injection using a micro syringe, (b) Single-shot sampler for flash pyrolysis using sample cup. (c) On-line micro reaction...

Brown, J. and Shirey, B. (2002) A Tool for Selecting an Adsorbent for Thermal Desorption Applications. Technical Report, T402025 EQF SUPELCO. 

U.S. EPA, Eco Eogic International Gas-Phase Chemical Reduction Process, The Thermal Desorption Enit Applications Analysis Report, EPA/540/AR-94/504, Washington, D.C., 1994. 

O. Nishimura, Application of a thermal desorption cold trap injector to multidimensional GC and GC-MS , J. High Resolut. Chromatogr. 18 699-704(1995). 

Chemisorption of simple diatomic molecules has usually been the object of thermal desorption studies. Recently, there has been a growing interest in the application of this method to the investigation of surface phenomena produced by more complex molecules which yield either fragment desorption products or catalytically formed species (35, 46a 46h). Also, physisorp-... 

Figure 5.22. Thermal desorption spectra after electrochemical O2 supply on Pt deposited on YSZ4,s at 673 K. The different curves correspond to various times of current application I=+I5 pA. Desorption was performed with linear heating rate, p=l K/s 2FNg/I=2570 s.4,7 Reprinted from ref. 7 with permission from Academic Press.

Applications The potential of a variety of direct solid sampling methods for in-polymer additive analysis by GC has been reviewed and critically evaluated, in particular, static and dynamic headspace, solid-phase microextraction and thermal desorption [33]. It has been reported that many more products were identified after SPME-GC-MS than after DHS-GC-MS [35], Off-line use of an amino SPE cartridge for sample cleanup and enrichment, followed by TLC, has allowed detection of 11 synthetic colours in beverage products at sub-ppm level [36], SFE-TLC was also used for the analysis of a vitamin oil mixture [16]. 

Different experimental approaches were applied in the past [6, 45] and in recent years [23, 46] to study the nature of the organic residue. But the results or their interpretation have been contradictory. Even at present, the application of modem analytical techniques and optimized electrochemical instruments have led to different results and all three particles given above, namely HCO, COH and CO, have been recently discussed as possible methanol intermediates [14,15,23,46,47]. We shall present here the results of recent investigations on the electrochemical oxidation of methanol by application of electrochemical thermal desorption mass spectroscopy (ECTDMS) on-line mass spectroscopy, and Fourier Transform IR-reflection-absorption spectroscopy (SNIFTIRS). 

One of the standard surface science methods for assessing the concentration and stability of a chemisorbed species is thermal desorption spectroscopy (TDS). An early paper by Redhead ( 7) developed the conceptual framework for certain cases. Many papers since then have expanded the applicability of this method. Recent work of Madix Q8) > Weinberg (9) and Schmidt CIO) is particularly noteworthy. Most of this work focuses on the desorption of a single molecular species and not on reactions in desorbing systems. However, qualitative features of the temperature dependence of reactions can be assessed using this method. Figures 1 and 2 taken from the... 

The book has been written as an introductory text, not as an exhaustive review. It is meant for students at the start of their Ph.D. projects and for anyone else who needs a concise introduction to catalyst characterization. Each chapter describes the physical background and principles of a technique, a few recent applications to illustrate the type of information that can be obtained, and an evaluation of possibilities and limitations. A chapter on case studies highlights a few important catalyst systems and illustrates how powerful combinations of techniques are. The appendix on the surface theory of metals and on chemical bonding at surfaces is included to provide better insight in the results of photoemission, vibrational spectroscopy and thermal desorption. 

Kester [5] has discussed the application of the purge and trap gas chromatographic method to the determination of aliphatic chloro-compounds in soil. Following methanol extraction of the soil the extract is gas purged and the purge gases trapped on a Tenax silica gel/ charcoal trap followed by thermal desorption from the trap and examination by gas chromatography and mass spectrometry. Compounds that have been determined by this method are listed in Table 5.1. 

Ayen, R.J., C.R. Palmer, and C.P. Swanstrom. 1994. Thermal desorption. Pp. 265-310 in Hazardous Waste Site Soil Remediation Theory and Application of Innovative Technologies. DJ. Wilson and A.N. Clarke, eds. New York, N.Y. Marcel Dekker. 

These liner exchange systems make feasible yet another analysis mode direct thermal desorption (DTD). Here the liner or an insert is packed with the solid sample. The liner exchange system can then be used in place of a conventional autosampler. The liner is automatically inserted into the PTV and the volatiles thermally desorbed onto the column. Some analysts may feel uneasy about such desorption from the solid phase how does one know that all of the volatile analytes have been released from the sample crystal lattice However, where applicable, this approach may not be as difficult to validate as one might imagine. For instance, the PTV can be cooled after the analyte transfer, and then, at the end of the chromatographic temperature programme, reheated to repeat the process. Ideally all of the analyte should transfer in the first cycle and none in the second, demonstrating that complete desorption occurs in the method. 

ETG supplied thermal desorption technology at the Southern Maryland Wood Treating Superfund site. From 1997 through 2000, it was estimated that the thermal desorption costs at the site were 60,450,429 (including pending costs and potential modifications). The estimated completion cost for this application was 221 per ton. This was within 4% of the estimated cost in the record of decision (ROD) ( 214 per ton) (D22906L, p. 20). 

KAL con s thermal units are applicable to treatment of hydrocarbon-contaminated soils but may not be used to remediate soils contaminated with polychlorinated biphenyls (PCBs), radioactive isotopes, or dioxins. Pesticides and herbicides can be treated by low-temperature thermal desorption, but special permitting is required and may be difficult to obtain. 

In 1993 through 1994, an IRV-100 thermal desorption unit was used to treat 13,986 yd of soil contaminated with trichloroethene (TCE) at the U.S. Department of Defense s (DOD s) Letterkenny Army Depot Superfund Site in Chambersburg, Pennsylvania. The total project costs were 5,402,801. This figure included 4,647,632 for McLaren/Hart s application of the thermal treatment, 192,827 for the DOD s design and projeet remediation, 249,320 for the DOD s design contract, and 312,320 for the DOD s construction contract management (D21039Z, p. 59). 

GEMEP is applicable to virtually all chemical forms of mercury, including those with very low vapor pressures, such as mercury oxide or sulfide. These high boiling compounds are problematic for thermal desorption. 

Thermal desorption is a technology that physically separates volatile and some semivolatile contaminants from contaminated media. In thermal desorption, heated air is used to volatilize contaminants at temperatures below those used for incineration. There are both in situ and ex situ applications of the technology. Ex situ treatments typically are used to remediate soil, sediments, sludges, and filter cakes. In situ applications of the technology use injected steam, thermal blankets, or heat supplied by electrodes to volatilize contaminants, which are then removed using extraction wells. 

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