Effect of Ionic Liquid Pretreatment on the Porosity of Pine: Insights from Small-Angle Neutron Scattering, Nitrogen Adsorption Analysis, and X-ray Diffraction

Abstract

Small-angle neutron scattering (SANS) was used to study the porosity of pine samples before and after ionic liquid (IL) pretreatment. Pine samples were pretreated using 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) at 110 °C for 3 h at biomass concentrations of 5, 10, 15, 20, and 25 wt % and at 130 °C for 3 h at biomass concentrations of 5 and 25 wt %. For the first time, relative changes in porosity of pretreated pine samples derived from SANS were compared with those obtained from the nitrogen adsorption analysis. Biomass crystalline structures were measured by X-ray diffraction (XRD). Both porosity and XRD data suggest that [C2C1Im][OAc] interacted with pine samples more efficiently at higher biomass concentrations during pretreatment. This was attributed to the presence of resin acid in the pine samples.

Structural changes in lignocellulosic biomass during activation with ionic liquids comprising 3-methylimidazolium cations and carboxylate anions

“…To streamline our efforts and provide direct comparison to previous studies, we focused our subsequent analyses only on the shortest (3 h) and the longest (72-h) activation times for each IL [ 22 , 49 , 50 ]. In addition, these activation times were selected on the basis that 72-h activated hybrid poplar biomass can enzymatically produce the same amount of glucose as samples activated for 3 h coupled with autohydrolysis [ 35 ].…”

Ionic Liquids in Biomass Processing

“…Biomass Reference 1-Ethyl-3-methylimidazolium acetate Bamboo, Hinoki Cypress wood, Sugarcane bagasse, Pine wood [81,82,83,84,85,86] Triethylammonium hydrogensulfate with 20 wt % water Miscanthus giganteus [68] Cholinium lysinate, Cholinium acetate Sorghum, Switchgrass, Eucalyptus, Pine [87,88,89] 1-Ethyl-3-methylimidazolium methanesulfonate Pine needles [90] 1-Butyl-3-methylimidazolium acetate Rice straw [91] 1-Ethyl-3-methylimidazolium acetate (42 wt. %) in DMSO Switchgrass [92] 1-Ethyl-3-methylimidazolium acetate, 1-Allyl-3-methylimidazolium formate and acetate…”