IRON COMPLEXES BY MOSSBAUER-SPECTROSCOPY IN EXTRACTS FROM POINT OF AYR COAL

Extracts from Point of Ayr coal prepared in two ways [in a flowing sol vent (tetralin) liquefaction experiment and the coal digest from the B ritish Coal pilot plant at Point of Ayr] have been examined by Mossbau er spectroscopy to investigate the chemical environment of the iron he ld as organic complexes in the extracts. The original Point of Ayr coa l has also been examined by Mossbauer spectroscopy to compare the mine ral iron profile with that of the extracts. The Mossbauer spectrum of the coal was very different from those of the extracts and may be inte rpreted as showing the presence of pyritic iron and the iron containin g mineral illite. Typical iron contents of the coal are less than 1%; while the estimated iron content of the extracts is less than 0.1%; th e ash content of the pilot plant digest is generally of the order of 0 .1%. The results show that the iron is not held as pyritic sulfur in m icroparticles within the extracts, but is present in the form of organ ic complexes. These complexes are likely to include porphyrin structur es and may also include other plant protein structures.