Dissolution of lignites in tetralin at ambient temperature: effects of ultraviolet irradiation

Abstract The effects of ultraviolet (UV) irradiation, acid treatment and sunlight on the dissolution of Turkish lignites in tetralin have been investigated. Original and 0.01 N HCl washed lignite samples were exposed to UV irradiation for 24, 48, 72, 96 and 120 h and two samples were also exposed to sunlight for 1, 2, 3 and 4 weeks. Tetrahydrofuran (THF) soluble products were separated into three fractions: hexane solubles (oils), toluene solubles (asphaltenes) and toluene insolubles (preasphaltenes). As the irradiation period increased from 24 to 120 h, the yield of THF solubles increased. Sunlight had similar effects. Solubilization of 50% of the organic structure can be achieved, however, the yield of THF solubles depends on the lignite samples. Removal of exchangeable cations resulted in a decrease in the THF solubles at longer reaction times.