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Detailed studies have been carried out on the distribution of organic functional groups and inorganic species in as-received (ar) and acid-washed (aw) brown coals using elemental analysis, energy dispersive X-ray analysis (SEM-EDX), X-ray photoelectron spectroscopy (XPS), and Time-of-flight−secondary ion mass spectrometry (TOF−SIMS). Surface concentrations of the various carbon groups, organic oxygen, and inorganic hydroxide were obtained using XPS, but oxygen from clay and quartz, if present, interfered with organic oxygen determinations for the coals. A comparison of ar and aw coals using XPS and SEM-EDX is provided in terms of inorganic and organic sulfur groups. Chloride in these coals is present mainly as acid extractable forms, but small amounts of chloride in the organic matrix were indicated by the elemental analysis of ultra low-ash coals. TOF−SIMS fragments from brown coals were indicative of polymers consisting mainly of single aromatic groups linked by hydrocarbons with carboxyl and phenol functional groups. Sulfur fragments were from inorganic sulfur, thiols, organo-sulfates, and S−N−organic species. Numerous fragments containing organically bound chloride were observed. Fragments of the inorganic species Na, Mg, Al, Si, K, Ca, Ti, Cr, Fe, Mn, Ni, Cu, and Ga were also observed. Environmentally undesirable species, particularly from organo-sulfur and organo-chloride groups in brown coal, are likely to emerge from processes that heat coal−water mixture.

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Chemical reactions between certain bis-cyclometalated iridium complexes, cerium(IV) and organic reducing agents in aqueous solution produce an emission of light which in some cases is more intense than that from analogous reactions with conventional ruthenium-based reagents, thus providing a new avenue for chemically-initiated luminescence detection.

The electrochemical and photophysical properties of biscyclometallated iridium(III) complexes containing phenanthroline-based ligands have been investigated and compared in organic and aqueous media. Complexes having general formula [Ir(ppy) +/-were synthesized, where ppy is the cyclometallating ligand, 2-phenylpyridine, and N _ N represents one of the following phenanthroline based ligands: 1,10-phenanthroline (phen), 4,7-diphenyl-1,10-phenanthroline (dpp) and 4,7-diphenyl-1,10-phenanthrolinedisulfonate (BPS). In the case of [Ir(ppy) 2 (BPS)] -, the SO 3 -group located on the phenyl ring of BPS dramatically increases the aqueous solubility of the complex compared to the dpp complex, which is only soluble in organic media. The chloride salt of the underivatized phen complex, though not as soluble as the BPS chelated complex, is sufficiently soluble (Ͼ 1 mM) for sensing and other applications in aqueous media. The electrochemical response depends markedly on the medium; all the complexes showed reversible behaviour in organic media, whereas the oxidative electrochemistry of [Ir(ppy) 2

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Iron hydroxy complexes were added to brown coal by a stepwise pH adjustment of solutions of Fe(III) mixed with coal. The amounts of NaOH used to adjust the pH and the amount of Fe(III) added to coal were consistent with the addition of both mono-and polynuclear iron complexes to coal. Analysis of the bulk sample and of the sample sieved into smaller and larger particles, and SEM-EDX examination of large and small particles, revealed an uneven distribution of iron, with higher concentrations in smaller coal particles. XPS and TOF-SIMS data show that monoand polynuclear iron species form in the coal samples. Computer molecular modeling has illustrated the structure and bonding of the mono-and polynuclear species in brown coal and the variation in the relative distribution of these species as the amount of added iron is increased. Computer models have also been used to show similarities between low-temperature pyrolysis of brown coal containing large amounts of iron and the thermal decomposition of iron carboxylates.

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