Effects of [Bmim][Cl] ionic liquid with different concentrations on the functional groups and wettability of coal

Abstract

In view of high dust concentration in coal mining and difficulty of traditional water injection in coal wetting, the effects of [Bmim][Cl] (1-butyl-3-methylimidazole chloride) ionic liquid with different concentrations on wetting performance and functional groups of coals have been studied. Optical droplet morphology analysis system and FTIR (Fourier transform infrared spectrometer) were used. The results showed that coal samples treated with [Bmim][Cl] ionic liquid had a significant change in the content of aliphatic groups. In the coal samples treated with 0% concentration [Bmim][Cl], the content of CH2 groups was 77.86%, CH3 groups was 14.07%. When [Bmim][Cl] concentration was 4%, the content of CH2 groups decreased to 24.55%, CH3 groups increased to 61.25%. Besides, the contact angle is the minimal of a 41.1° at 4% ionic liquid concentration. The relationship between contact angles and contents of functional groups were analyzed. Results showed that the content of CH3 groups and CH2 groups had the greatest effect on the contact angle and 4% [Bmim][Cl] ionic liquid treatment can effectively reduce the contact angle and improve the coal wettability. It is of great significance to increase coal wettability and reduce dust generation by changing the contents of functional groups.