Influence of oxidation in aqueous medium on the structure and properties of lignites

In this paper, the effect of oxygen uptake on the structure and properties of lignites was investigated using five different Turkish lignites. Lignite samples were oxidized in aqueous medium at 423 K under 1.5 MPa partial pressure of oxygen for 60 min. Relations between the oxygen uptake and the elemental compositions of the lignite samples were investigated. FT-i.r. technique was applied to the original and oxidized lignite samples to investigate functional group analyses. Mercury porosimetry analyses of the samples were carried out up to about 220 MPa. Effect of oxygen uptake on the bulk density, apparent density, porosity, and pore radius of the lignite samples were compared. Differential Thermogravimetry (DTG) technique was performed to compare the thermal reactivity of the original and oxidized lignite samples.