Thermal performance analysis of sugarcane bagasse pretreated by ionic liquids

Abstract This work investigated the pretreatment effect of four ionic liquids (ILs) on sugarcane bagasse (SCB) through reactivity, kinetic, and thermodynamic analysis. The ILs used in this study were 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]), 1-butyl-3-methylimidazolium methylsulfate ([Bmim][MeSO4]), Tris (2-hydroxyethyl) methylammonium methylsulfate ([MTEOA][MeSO4]), and trihexyltetradecylphosphonium chloride ([P66614] [Cl]). Pretreatment was carried out at 150 °C and 30 min, followed by thermal analysis of samples in a thermogravimetric analyzer (TGA). The activity parameters were obtained using TGA data. [P66614] [Cl] was completely absorbed in SCB, which strongly influenced the thermochemical behavior of [P66614] [Cl] treated sample. Results revealed that IL pretreatment greatly reduced ash content and increased the higher heating value (HHV) of SCB. Chemical composition analysis showed delignification of SCB by [Bmim][Cl], [Bmim][MeSO4] and [MTEOA][MeSO4]. However, [P66614] [Cl] increased lignin content indicating thermal stability. The obtained values of activation energy (Ea) for [Bmim][Cl], [Bmim][MeSO4], and [MTEOA][MeSO4] were much lower than that for untreated SCB, suggesting destruction of the lignocellulosic structure. Higher entropy change (ΔS) values after IL treatment implied higher disorder due to the breakage of SCB structure. The study demonstrated that the nature of cations and anions strongly influences the pretreatment potential of ILs for biomass undergoing thermochemical conversion processes.