Nature of the electron paramagnetic resonance intensity in iodine treated coals

✍ Scribed by Kurt S. Rothenberger; Richard F. Sprecher; Herbert L. Retcofsky; Wei Wangi; R.B. Clarkson; R.L. Belford

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 766 KB
• Volume: 73
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(94)90138-4

✦ Synopsis

Three British coals and their iodine treated counterparts were examined in order to investigate the increase in electron paramagnetic resonance (e.p.r.) signal intensity that occurs upon iodine uptake. The iodine is not removed by vacuum. Scanning electron microscopy (SEM) results show that the iodine exists in a highly dispersed form. Correlation of elemental analysis and e.p.r. spin density measurements indicates two to ten new spins added per 100 added I, molecules. A study of e.p.r. intensity as a function of temperature reveals nearly identical trends for untreated and iodine treated coals. High frequency e.p.r. resolves additional signal at lower fields in the iodine treated samples. Such observations contradict the notion of donor-acceptor complex formation between iodine and aromatic constituents of the coal. Although there is considerable evidence of iodine participation in the formation of this additional signal, it would appear to be of a non-bonding nature.