(407c) Only the Strong Survive: Saccharification Residues and Their Qualities As Lignocellulose By-Products

The biochemical platform for production of biofuels has progressed significantly in terms of conversion efficiency and net yields, but a portion of lignocellulosic plant tissue inevitably resists conversion. This residue portion, by the nature of its own recalcitrance, has qualities that differ from the starting material. Specifically, the enzymatic hydrolysis (saccharification) and dissolution of carbohydrate fractions leaves behind cellulose that is both highly crystalline and naturally well-dispersed in a lignin matrix. While often seen as an inefficiency, we are adopting the view that this is useful pre-processing amenable to making solid materials. As post-saccharification co-products from aspen and poplar, we are testing the potential to make lignin-based binderless films and adhesives reinforced in situ by cellulose nanocrystals. The work presented here relates to our objectives to examine pretreatment effects on material residue properties, including carbon fractions, hydroxyl content, crystallinity of carbohydrates, and porosity, in addition to simple yield of monomer sugars from polymeric holocellulose. The influence of pretreatment types, as alkaline, acid, or oxidative, is presented, using a time series of saccharification to modulate yields across a spectrum. This allows comparison at equal yields as well as among residues created upon complete saccharification. Additionally, a treatment severity index was used to equalize pretreatment parameters, although it was clear that this severity index was oversimplified using our approach, specifically for oxidative pretreatments. An additional component, laccase-catalyzed activation of the lignin binder, has also been included and its progress will be presented. The basic characterization in our work not only forms the basis for our ongoing work making solid materials from this residue matrix, but also provides valuable fundamental information on the chemical properties of saccharification residues to be used toward any co-product strategy.