Influence of pretreatment on solvent-swelling and extraction of some Turkish lignites ☆

Abstract

In this study, three Turkish lignites (Beypazarı (LGN-1), Gölbaşı (LGN-2) and Kangal (LGN-3)) have been pretreated with the solutions of 0.1N HCl, 10% HCl, HCl–HF or with air oxidation at 200 °C. Swelling ratios of original and pretreated lignites have been determined by using 11 different solvents. Original and pretreated samples have been subjected to preswollen by using THF at room temperature. Toluene Soxhlet extraction experiments of these and unswollen samples have been also carried out. The effect of solvent swelling ratio on the extraction yields of the original and pretreated lignites have been examined. The results showed that the swelling ratios were high in hydrogen bonding solvents but low in non-hydrogen bonding solvents. It is found that the best solvent is 2-ethanolamine and second is pyridine for these lignites. The pretreatment increased the swelling values of the lignites by all solvents. Comparing with original lignites in all solvents except pyridine and 2-ethanolamine, the swelling values were not changed by oxidation. The results have indicated that both swelling and extraction yields generally increased after the pretreatments and the increments are higher with hydrogen bonding solvents.