IonoSolv pretreatment using protic ionic liquids has shown impressive sugar fractionation ability and recyclability. Lignin condensation during ionoSolov pretreatment can lower its economic value and potentially limit the valorisation of...

The study focused on the dual role of water as a cosolvent and an antisolvent in the [HSO4]-based protic ionic liquid biomass fractionation process using N,N,N-dimethylbutylammonium hydrogen sulfate, [DMBA]­[HSO4]. The effectiveness of biomass fractionation using [DMBA]­[HSO4] mixed with different concentrations of water of conventional biorefinery feedstocks (Miscanthus and pine softwood) and nonconventional low-cost lignocellulosic biomass waste (treated timber and postconsumer waste wood) was investigated. The pulp composition, lignin extraction, and enzymatic hydrolysis of the cellulose pulp were analyzed after pretreatment at 170 °C for 30 min. We showed that it is possible to reduce the ionic liquid use in the process by increasing the water concentration as a cosolvent while still maintaining the effective biomass deconstruction forMiscanthus and postconsumer waste wood. However, softwood biomass showed higher resistance to fractionation at higher water concentrations in the pretreatment medium. We also investigated the impact of reducing the amount of water used as an antisolvent for lignin precipitation in terms of lignin yields and properties. The robust performance of the fractionation process at the optimized antisolvent use was demonstrated using the challenging feedstock pine softwood over six pretreatment cycles. Finally, we demonstrated the significance of evaluating water use for the energy requirements of the process, particularly in the ionic liquid regeneration step, achieving a 65% energy reduction.

Postconsumer waste wood is one of the most highly generated and yet overlooked waste streams that are typically sent to landfills or hazardous incineration facilities. This study presents the valorization of real postconsumer metal-contaminated waste wood as viable biorefinery feedstock using the ionoSolv process. Waste wood characterization showed high levels of heavy metal contamination originating from preservatives, paints, and pigments. Several ionic liquids (ILs) were screened to investigate their effectiveness in fractionating waste wood quantified by lignin and hemicellulose removal, glucan recovery, enzymatic saccharification yield, and their effectiveness in extracting the heavy metals from the biomass. 1-Methylimidazolium chloride [H1Cim]Cl IL was shown to be the most effective in fractionating the waste wood, achieving quantitative glucose yield, while simultaneously extracting 84–96% of heavy metals under optimum conditions. The effect of increasing the solid loading on pretreatment fractionation efficiency also was investigated, as well as on heavy metal extractions, with 74–95% extractions being achieved at solid to solvent loadings of 1:2 g g–1. Electrodeposition of Pb was also demonstrated at low overpotentials. This is the first example of turning hazardous waste wood that has low to negative value to its producers into value-added products in a biorefinery scheme.

This study investigates the use of the protic ionic liquid (IL) N,N,Ndimethylbutylammonium hydrogen sulfate [DMBA][HSO 4 ] to effectively valorize and decontaminate hazardous creosote-treated timber. We found that [DMBA][HSO 4 ] mixed with 20 wt % water is capable of fractionating creosote-treated timber into a cellulose-rich pulp and lignin stream at a high solid loading of 1:5 g g −1 . Pretreatment severity plays an essential role in the process fractionation performance with delignification reaching 60% and enzymatic saccharification of cellulose-rich pulps, exceeding 70% of the theoretical maximum achieved under the highest investigated pretreatment severity conditions (170 °C, 45 min, and 20 wt % water content as a cosolvent). We report that the nonhydrophobic protic IL [DMBA][HSO 4 ] is highly effective in extracting polycyclic aromatic hydrocarbons (PAHs) from the creosote embedded in the timber, producing a highly digestible, PAH-free cellulose-rich pulp. Analysis of the fate of PAH compounds in the process streams (feedstock, IL liquor, cellulose pulp, and lignin) showed the high tendency of the PAHs to precipitate with lignin upon the addition of water as an antisolvent. The study demonstrates a novel application of protic [HSO 4 ]-based ILs in fractionating and decontaminating creosote-treated, unutilized hazardous biomass waste to produce inexpensive highly digestible cellulose substrates for second-generation biofuel production.

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