Darryn W. Rackemann

Organosolv pretreatment of plant biomass for enhanced enzymatic saccharification

The combination of dwindling petroleum reserves and population growth make the development of renewable energy and chemical resources more pressing than ever before. Plant biomass is the most abundant renewable source of energy and chemicals. Enzymes can selectively convert the polysaccharides in plant biomass into simple sugars which can then be upgraded to liquid fuels and platform chemicals using biological and/or chemical processes. Pretreatment is essential for efficient enzymatic saccharification of plant biomass and this article provides an overview of how organic solvent (organosolv) pretreatments affect the structure and chemistry of plant biomass, and how these changes enhance enzymatic saccharification. A comparison between organosolv pretreatments utilizing broadly different classes of solvents (i.e., low boiling point, high boiling point, and biphasic) is presented, with a focus on solvent recovery and formation of by-products. The reaction mechanisms that give rise to these by-products are investigated and strategies to minimize by-product formation are suggested. Finally, process simulations of organosolv pretreatments are compared and contrasted, and discussed in the context of an industrial-scale plant biomass to fermentable sugar process.

The effect of pretreatment on methanesulfonic acid-catalyzed hydrolysis of bagasse to levulinic acid, formic acid, and furfural

A major challenge that must be overcome for the commercial production of levulinic acid from lignocellulosics is to reduce equipment blockage and corrosion. Methanesulfonic acid (MSA), a relatively low corrosive acid, was used to produce organic acids and furfural from pretreated sugarcane bagasse. In general, the type of pretreatment did not affect levulinic acid yield, though it affected furfural yield. However, soda pretreated bagasse produced the highest yields of levulinic acid (∼75 mol%) and furfural (∼85 mol%), albeit under optimized conditions. Hydrolysis residue consists primarily of lignin that has been modified and/or condensed to humic substances, fatty acids, and oligomeric sugars. A conceptual biorefinery utilizing 1 ton of dry bagasse, alkaline-pretreatment, and MSA as a catalyst produced 165 kg soda lignin, 190 kg and 89 kg of levulinic acid and formic acid respectively, and 40 kg furfural.

An experimental investigation of bubble rise characteristics in a crystal suspended non-Newtonian fluid

An experimental study of the bubble rise characteristics in non‐Newtonian fluid with crystal suspension is presented in this paper. The suspension was made of different concentration of xanthan gum solutions with 0.23 mm polystyrene crystal particle. Different percentage of crystal content (by weight) was used to vary rheological properties. The effect of crystal particles and bubble volumes on the bubble rise velocity and bubble trajectory is analysed. The results show that the average bubble velocity increases with the increase in bubble volume for crystal suspended xanthan gum solution. In trajectory analysis, it is seen that the small bubbles experienced less horizontal motion in crystal suspended xanthan gum solution while larger bubbles followed a spiral motion. Experimentally determined data for the drag coefficient at high Reynolds number are compared with the results of other analytical and experimental studies available in the literature. The reported experimental data of drag co‐efficient incre...

Degradation of phenethoxybenzene in sodium hydroxide

Simple lignin model compounds containing β-O-4 aryl ether linkages have been utilized as a means to understand lignin depolymerisation. The effects of reaction temperature, time, catalyst concentration, and initial phenethoxybenzene (PEB) concentration on the degradation of PEB in NaOH were investigated. Operating at 300 °C for 1 h resulted in the highest combined yield of the primary products, phenol and styrene, and also resulted in a reduced amount of degradation products formed. The proportion of oligomeric and polymeric materials formed depended on the NaOH concentration, but not on the initial PEB concentration for equal reaction time. The results were used to suggest probable reaction pathways for PEB degradation.