Inhibition of Spontaneous Combustion Characteristic of Biomass Treated with Imidazolium-Based Ionic Liquids Using Thermogravimetric Analysis

The co-firing of biomass is now widely acceptable as a clean coal technology option, and the storage and transportation of this fuel are essential as fuels ignite on their own. Spontaneous combustion (SPONCOM) is a wellknown phenomenon in the coal mining sector, but little is known of the inherent properties of biomass toward SPONCOM. This study assessed the influence of three imidazolium-base ionic liquids (ILs), [Bmim(+)HSO(4)(-)], [Emim(+)HSO(4)(-)], and [Bmim(+)OAc(-)] on the SPONCOM liability of Sersia lancea biomass sample harvested from the Vaal River Mine, South Africa. The results of the derivative thermogravimetric (DTG) analysis of this indigenous biomass showed that it is highly liable to SPONCOM prior to treatment with ILs. Following treatment with all three ILs, the DTG results showed that ILs can potentially inhibit the SPONCOM liability of biomass, with [Bmim(+)OAc(-)] showing the best inhibitory effects. With [Bmim(+)OAc(-)] (IL-C), the TGspc index of S. lancea biomass was reduced to 0.0207 from 0.1457%/degrees C min(-1), and the sample was classified as low reactive after treatment. This indicates that less oxygen was consumed by the treated samples with [Bmim(+)OAc(-)] than by the untreated ones. From the textural properties of the IL-treated biomass, the mechanism responsible for the lower liability of the treated biomass was determined. This study establishes that biomass is very reactive, and it is important to understand its liability to SPONCOM, before being shipped as a fired or co-fired fuel across the Atlantic.