Using surface free energy method to evaluate the isothermic adsorption of free fatty acid on low-grade coal

Abstract

Surface free energy analysis on low-grade coal has been conducted. This research shows the interaction between oil and coal which improve the quality of low-grade coal by coating process. Sample coal has a total surface free energy of 22.3 mJ/m2 with 17.51 % polar ratio. The interfacial energy between coal and free fatty acid (FFA) is 9.1 mJ/m2 with adhesive energy by 53.4 mJ/m2 which is able the oil to coated on the coal surface under Van der Waals force effect.