Authors:
Luciane P. C. Romão, Ângelo Augusto M J. Silva, Fabiana A. Lobo, Danielle Goveia, Leonardo F. Fraceto, Julio C. Rocha, Peter Burba and André H. Rosa
Book:
After Wise Use – The Future of Peatlands, Proceedings of the 13th International Peat Congress: Peat Balneology
Keywords:
balneological-peat, dissolved-organic-matter, extractants, extraction-kinetics, metal
Documentfile:
Romão et al. 2008: Extraction and exchange behavior of metal species
Summary:
The binding and availability of metals (Al, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb) in therapeutically applied peat was characterised by means of a versatile extraction approach. Aqueous extracts of peat were obtained by a stan- dardized batch equilibrium procedure using high-purity water (pH 4.5 and 5.0), 0.01 mol/L ethylenediaminete- traacetic acid and 0.01 mol/L diethylenetriaminepenta-acetic acid solution as metal extractants. Metal determinations were performed by atomic spectrometry methods and dissolved organic matter (DOM) was char- acterised by UV/VIS. Of the extractants studied Ca, Mg and Mn were the most available metals, in contrast to peat-bound Fe and Al. A pH increase favored the extraction of metals and DOM from peat revealing complex ex- traction kinetics. Moreover, a competitive exchange between peat-bound metal species and added Cu(II) ions showed that >100 mg of Cu(II) per 50 g wet peat were necessary to exchange the maximum of bound metals.