Fluid Behavior of Woody Biomass Slurry during Hydrothermal Treatment

Abstract

Hydrothermal experiment of woody biomass was carried out in an autoclave, and a property change of the woody slurry associated with hydrothermal reaction was analyzed. The reaction conditions, such as reaction temperature, reaction period, and slurry concentration, were varied in this experiment, and the effect of the hydrothermal conditions on the slurry characteristics was evaluated. To evaluate the property change of the woody slurry, apparent viscosity, particle size, pH, and ζ potential measurements of the hydrothermally influenced slurry were conducted. The fluid resistance of the slurry during hydrothermal experiment was also measured with an autoclave reactor. With application of hydrothermal treatment on a woody slurry, significant change of the slurry property was observed. The particle size decreased during hydrothermal experiment with increasing reaction temperature, and this particle size change influenced the slurry behavior. Due to the particle size reduction, the apparent viscosity of the treated slurry became smaller, and the treated slurry showed strong pseudoplastic fluid behavior. With a longer reaction period, the particle size was getting smaller by the hydrolysis reaction; however, particle size enlargement caused by a swelling and/or agglomeration occurred when the reactor’s temperature started to increase. This particle size enlargement behavior at the beginning of the hydrothermal experiment increased the fluid resistance of the slurry significantly. pH value and the ζ potential value were also influenced by the hydrothermal treatment. pH and absolute ζ potential values dropped with increasing reaction temperature; however, the absolute ζ potential value of the slurry reversely increased when the reaction temperature was over 523 K. The increment of carboxyl radical on the surface of the reacted particle changed particle−particle and particle−solvent interactions.

The mechanisms of hydrothermal deconstruction of lignocellulose: New insights from thermal–analytical and complementary studies

“…Second generation bioethanol processes are based on the fermentation of sugars derived from the cellulose and hemicellulose components of lignocellulosic plant materials. Considerable research and development activity has centred on the application of either auto- or acid-catalysed hydrothermal treatments for preliminary deconstruction of the plant cell wall ( Kobayashi et al, 2011; Alvira et al, 2010; Talebnia et al, 2010 ). Such treatments are necessary to improve the enzyme digestibility of the lignocellulosic feedstock, to allow the intractable cellulose fraction to be converted to glucose sugars for fermentation to ethanol.…”