Elsevier

Bioresource Technology

Volume 272, January 2019, Pages 288-299
Bioresource Technology

Low liquid ammonia treatment of wheat straw increased enzymatic cell wall polysaccharide degradability and decreased residual hydroxycinnamic acids

https://doi.org/10.1016/j.biortech.2018.10.025Get rights and content
Under a Creative Commons license
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Highlights

  • LLA treatment of wheat straw results in high carbohydrate recovery.

  • LLA treatment of wheat straw decreases relative abundance of hydroxycinnamic acids.

  • Treatment time, together with NH3 concentration, affects enzymatic hydrolysis.

  • Low NH3 loadings loosen the lignocellulose architecture.

Abstract

Ammonia treatment of lignocellulose improves carbohydrate degradability, however, low ammonia dose treatment effects and mechanisms are hardly considered. This study describes low dose ammonia treatment of wheat straw in a statistical design of experiments (Taguchi design) to evaluate the effects of ammonia concentration, treatment time and the Solid:Liquid ratio on structure, composition and enzymatic degradability of the residual fractions. The results showed that low ammonia concentration (≤2 w/w % NH3) resulted in a high carbohydrate recovery (>80%) coupled enzymatic hydrolysis of 50% of xylan and 40% of glucan of the treated material using a (hemi-) cellulase enzyme cocktail. This effect coincidences with the relative decrease in ferulic acid by 10% and coumaric acid by more than 50% analysed via pyrolysis-GC–MS, measured as 4-vinyl-phenol and 4-vinyl-guaiacol, respectively. Our findings show that lowering ammonia concentration increased the effect of treatment time on the enzymatic degradability of the residual fraction.

Keywords

Lignocellulosic biomass
Ammonium hydroxide
Low-liquid ammonia (LLA) treatment
Taguchi method
Wheat straw

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