Mechano-chemical pretreatments of lignocellulose for the effective recovery of fermentable sugars

Abstract

This research is focused on the development of pretreatment methods for lignocelluloses in the broader context of a biorefinery. In the first two studies, a laboratory twin-gear reactor (TGR) was investigated as new means for the handling of thick biomass slurries. This high shear stress device was used as a base of thermo-mechanical action for the pretreatment of high solids loading of biomass. By adapting new pretreatment pathways, its unique helical gears were able to disrupt the biomass structure to significantly reduce the subsequent enzyme dosage for an enhanced sugar yield. Although this TGR was effective enough but at the same time it offers the loss of the biomass components. Therefore, for the remaining studies I used different approaches without the use of TGR to address above issues. In my next study, I introduced a new persulphate based oxidative pretreatment. I used potassium persulphate to induce Fenton-like reaction for the disruption of biomass structure. This pretreatment was unique in a sense that it does not dissolve any component of biomass and escalated the hydrolysis yield. Although, this new oxidative pretreatment was indeed a drastic approach but at the same time it was prohibitively expensive. So, in the last two studies new approaches were investigated to enhance the economics of a biorefinery operation. In first study, ammonium carbonate (AC) was introduced as a zero cost catalyst. This AC pretreatment, specifically combined with a $CO_2$ capture process, was found effective for the pretreatment and it also provided a nitrogen supplement in the subsequent fermentation process. In the last study, I introduced $FeCl_3$ as a duel function catalyst for the pretreatment as well as for the production of biochemicals. This catalyst has the regeneration capability after the pretreatment and thus can be helpful to reduce the financial burdens of a biorefinery.