Abstract
A brown coal was swollen in binary solvents, including different pyridine/benzene and dimethyl sulfoxide/benzene mixtures. The amount of hydroxylic hydrogen remaining immobile (f_<IM(OH)>) was experimentally determined by using pulsed ^1H NMR technique as a function of the swelling ratio (Q). These observations were theoretically assessed by using the association model. The model yields a equilibrium constants for the formation of hydrogen bonds between coal molecules, K_B. Given the K_B, the Flory-Huggins equation was partially modified to account for hydrogen bonding. The modified equation was applied to the coal, resulting that the number of statistical segments between junction points is small.
