Effects of Chain Alkanes on Restraining Water Re-Adsorption of Dried Indonesian Lignite

An Indonesian lignite (IN) was hydrothermally treated at 150–250°C for 20 min and the treated samples were mixed with different amounts of different chain alkanes. The water re-adsorption tests were measured using a desiccator method. To reveal the mechanism of chain alkanes restraining water re-adsorption of lignite, the changes in some physicochemical properties were characterized by Fourier transform infrared spectrometry, N 2 adsorption-desorption, and thermogravimetric (TG) analysis. The results showed that the water re-adsorption contents of all samples decreased with increasing content of chain alkanes; this is because the addition of chain alkanes could cover some oxygen-containing functional groups on the surface of lignite and block partial pores in lignite, which became much obvious with increasing amount of chain alkanes. Moreover, the water re-adsorption content first increased and then decreased as the chain length of alkanes increased, and octane showed the optimum effect on restraining water re-adsorption.