Wet Air Oxidation Pretreatment of Mixed Lignocellulosic Biomass to Enhance Enzymatic Convertibility

Abstract

The present work explores the potential of wet air oxidation (WAO) for pretreatment of mixed lignocellulosic biomass to enhance enzymatic convertibility. Rice husk and wheat straw mixture (1:1 mass ratio) was used as a model mixed lignocellulosic biomass. Post-WAO treatment, cellulose recovery in the solid fraction was in the range of 86% to 99%, accompanied by a significant increase in enzymatic hydrolysis of cellulose present in the solid fraction. The highest enzymatic conversion efficiency, 63% (by weight), was achieved for the mixed biomass pretreated at 195°C, 5 bar, 10 minutes compared to only 19% in the untreated biomass. The pretreatment under the aforesaid condition also facilitated 52% lignin removal and 67% hemicellulose solubilization. A statistical design of experiments on WAO process conditions was conducted to understand the effect of process parameters on pretreatment, and the predicted responses were found to be in close agreement with the experimental data. Enzymatic hydrolysis experiments with WAO liquid fraction as diluent showed favorable results with sugar enhancement up to 10.4 g L -1 .

Production of high concentrated cellulosic ethanol by acetone/water oxidized pretreated beech wood

“…In this case, it is the hemicellulose that is most readily hydrolyzed, while the lignin is solubilized but not as effectively as in the AWO where acetone/water ratios are 1:1 or 3:1. Typical lignin removal for wet oxidation has been found to be up to 50 wt% with the mechanism being that of an attack on the double bonds of the phenolics present in lignin and the ether bonds [ 25 , 26 ]. The addition of acetone in run no.…”

Role of advanced oxidation processes in lignocellulose pretreatment towards biorefinery applications: a review on emerging trends and economic considerations

“…Another study 36 explored the application of WAO in common reed ( Phragmites australis ), achieving the most favorable outcomes at a temperature of 195 °C for a duration of 12 min. This treatment resulted in the solubilization of 51.7% hemicellulose and 58.4% lignin, with 87.1% cellulose remaining in its solid state.…”

Investigation of different pretreatment methods of Mediterranean-type ecosystem agricultural residues: characterisation of pretreatment products, high-solids enzymatic hydrolysis and bioethanol production

“…The pretreatment of biomass in the production of second-generation bioethanol is crucial and aims at disrupting the recalcitrant structure of lignocellulose by removing hemicellulose and/or lignin in order to enhance enzymatic cellulose hydrolysis. A variety of pretreatment methods have been applied for ethanol production from lignocellulose in general such as milling [21], dilute acid [22], hydrothermal [23], organosolv [24], wet oxidation [25], steam explosion [26] and ammonia fiber explosion (AFEX) [27]; and from olive pruning residue in particular including hydrothermal [28], dilute acid [29], steam explosion [30], FeCl 3 and organosolv [31]. Among the most promising is dilute acid pretreatment as it combines high reaction rates, low cost and low catalyst consumption with a high efficiency in hemicellulose removal and an increase in the enzymatic digestibility of biomass [22].…”