Toward a Circular Economy: Decontamination and Valorization of Postconsumer Waste Wood using the ionoSolv Process
Abouelela, A.R.; Tan, S.; Kelsall, G.H.; Hallett, J.P.
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.