UCI KCCAMS Graphitization protocol

UCI KCCAMS Graphitization protocol - UCI KCCAMS Facility...

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UCI KCCAMS Facility Graphitization protocol - Hydrogen reduction method February 25, 2005
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Contents I. Introduction page 2 II. Graphitization reaction page 2 III. Graphitization procedure page 2 IV. Preconditioning the Fe catalyst page 4 V. Preparation for graphitization page 7 VI. Graphitization page 8 VI.1. Using combusted samples page 8 VI.2. Leaching carbonate samples. page 11 VI.3. Acidified carbonate samples page 11 VII. Graphitizing a standard (x4 standard) page 14 VIII. Hydrogen Addition page 15 IX. Post-graphitization procedures (collecting your sample) page 18 X. Changing the magnesium perchlorate page 19 XI. How to make a slush page 19 XII. References page 20 List of Figures Fig. 1 Picture showing main section of graphitization line with labels. page 3 Fig. 2 Tools necessary to load Fe-catalyst into the graphitization line. page 4 Fig. 3 a & b Valve in closed position 3b. Valve in open position. page 5 Fig. 4 Hydrogen cylinder with labeled valves. page 5 Fig. 5 Control locations to set temperature and timer. page 6 Fig. 6 An example of an index card. page 7 Fig. 7 Bellows with detachable end support. page 8 Fig. 8 Placement of liquid nitrogen. page 9 Fig. 9 Vacutainer on graphitization line to make a vacuum in the tube. page 12 Fig. 10 Syringe turned upside-down and plunger pushed in to expel air bubbles. page 13 Fig. 11 Needle piercing through septum, then plunger puched to expel acid. page 13 Fig. 12 Sample containing Vacutainers on the heating block. page 13 Fig. 13 Showing proper distance of the heater from the ultra torr fittings. page 17 Fig. 14 Example of how heaters should be put away. page 18 Fig. 15 Ice shaver with labeled parts. page 20 1
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I. Introduction In the 14 C AMS technique, the element of interest (carbon sample) is chemically separated from the original sample and loaded as a solid target (graphite) in the sputter ion source of the tandem accelerator. The procedure to convert the raw sample material into a graphite target suitable for the ion source includes a series of necessary steps (removal of macroscopic contaminants, chemical cleaning procedures, combustion and graphitization). These steps are essential for a reliable AMS measurement. This protocol outlines the graphite sample preparation procedure at UCI KCCAMS prep- laboratory for organic and carbonate samples . Through this process the CO 2 produced from carbonaceous raw materials is cryogenically purified (separated from non-combustible gases) and reduced to solid graphite. II. Graphitization reaction To catalyze the production of small amounts of elemental carbon from CO 2 , we use the Bosch reaction (Manning and Reid, 1977) that can be summarized as: CO 2 +2H 2 550 - 650°C C + 2H 2 O Catalyst (Fe) The reaction takes place as two successive reductions: first to carbon monoxide and then to carbon, which permeates and adheres to the surface of the iron powder (catalyst). More details on graphitization can be found in Vogel et al, 1984. During the graphitization procedure at the KCCAMS prep-lab, cryogenically purified CO
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This note was uploaded on 09/27/2010 for the course 456 9852 taught by Professor Chaohue during the Spring '10 term at Mackenzie.

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UCI KCCAMS Graphitization protocol - UCI KCCAMS Facility...

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