EFFECT OF PRESWELLING ON SOXHLET AND SUPERCRITICAL GAS EXTRACTION OF A TURKISH LIGNITE

Preswelling of Mugla-Yatagan lignite with THF (Tetrahydrofuran) followed by removal of the swelling agents results in higher extract yields, probably because the solvent molecules had easier access to the expanded pore structure of the swollen lignite. On the other hand, the yields of supercritical THF extract of the same lignite sample indicated that during removal of the swelling agent the expanded pore structure had collapsed. The results show that higher extract yields might have been obtained by the combined effect of the expanded pore structure of the swollen lignite and the solvent power of the mixed solvent ,i.e., of the mixture of swelling agent and supercritical extraction fluid.