Organosolv pretreatment of oat husk using oxalic acid as an alternative organic acid and its potential applications in biorefinery

Abstract

In this study, ethanol organosolv treatment of oat husk and the potential effects of phosphoric acid and oxalic acid as alternatives to sulfuric acid were investigated. These acids were determined as effective as sulfuric acid to obtain high quality lignin and glucan and they can be used instead of sulfuric acid in solvent acidification. To determine the purity and recovery of both lignin and glucan, the effects of initial substrate amount, solid-to-liquid ratio, and amount of washing solutions were also examined using a one-factor-at-a-time strategy. Reducing the amount of washing solutions (water, solvent, or both) negatively affected lignin recovery, but it did not affect glucan recovery. The optimum conditions for pretreatment of the oat husk at higher glucan recovery were obtained with 50% aqueous ethanol acidified with oxalic acid at 210 °C for 90 min and solid-to-liquid ratio of 1:2. In the mixture of evaporated glucan-rich and hemicellulose-rich fractions obtained through the optimized condition, 4.62 g/L biomass containing 10.27% protein was produced by the cultivation of Aspergillus oryzae. The fractions obtained from organosolv treatment can be used to obtain value-added products such as biomass production, and thus contributing to a sustainable economy by integrating lignocellulosic substrate residues into the biorefinery.

Towards a Complete Exploitation of Brewers’ Spent Grain from a Circular Economy Perspective

“…Recently, some innovative biomass DES-based treatments have been reported in the literature in the context of exploiting agricultural waste in biorefineries [51][52][53]. However, the described treatments were mainly focused on the obtainment of a high quantity of fermentable sugars as in the majority of the research concerning biomass exploitation [54]. In this work, a new protocol of biomass DES-based treatment coupled with the previous sugar process step (described in Section 3.1) has been set up with the special aim of lignin recovery and exploitation.…”

Organosolv pretreatment: an in-depth purview of mechanics of the system

“…From the liquid fraction of pretreated poplar wood, ~ 40.22 g/L fermentable sugars were retrieved and utilized for subsequent saccharification and fermentation (SSF) to generate bioethanol (8.6 g/L) (Kim et al 2009 ). In addition, recently Sar et al ( 2022 ) used oak husk and provided ethanol organosolv treatment, where H 2 SO 4 was substituted by phosphoric and oxalic acids and various parameters were explored using a one-factor-at-a-time approach. It was reported that the deduction in washing with solutions, i.e., water/solvent/both did not affect glucan recovery but did impact lignin recovery negatively.…”

Production of Cellulose Materials from Oat Agricultural Wastes: A Review of Recent Approaches

“…The method of organosolv treatment has already been applied for processing of miscanthus [121], wheat straw [122-124], eucalyptus biomass [125], bamboo [126], pine [127,128], bagasse [129], rice straw [130,131], birch [132], abies wood [133]. The method has low cost and the ability to reuse solvents [134]. However, the process is carried out at high temperatures, and the equipment used in the process have to be resistant to elevated pressure.…”