Liquor re-use strategy in lignocellulosic biomass fractionation with ethanol-water mixtures

Determination of Kinetic and Thermodynamic Parameters of Pyrolysis of Coal and Sugarcane Bagasse Blends Pretreated by Ionic Liquid: A Step towards Optimization of Energy Systems

Pyrolysis behavior of ionic liquid (IL) pretreated coal and sugarcane bagasse (SCB) blends through thermogravimetric analysis (TGA) was studied. Three blends of coal and SCB having 3:1, 1:1, and 1:3 ratios by weight were treated with 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) at 150 °C for 3 h. Untreated and IL treated blends were then analyzed under pyrolytic conditions in a TGA at a constant ramp rate of 20 °C/min. Kinetic and thermodynamic parameters were evaluated using ten Coats-Redfern (CR) models to assess reaction mechanism. Results showed that the untreated blends followed a definite pattern and were proportional to the concentration of SCB in the blends. IL treated blends exhibited a higher average rate of degradation and total weight loss, indicating that IL had disrupted the cross-linking structure of coal and lignocellulosic structure of SCB. This will enhance the energy generation potential of biomass through thermochemical conversion processes. The lower activation energy (Ea) was calculated for IL treated blends, revealing facile thermal decomposition after IL treatment. Thermodynamic parameters, enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS), revealed that the pyrolysis reactions were endothermic. This study would help in designing optimized thermochemical conversion systems for energy generation.

Enzymatic hydrolysis of several pretreated lignocellulosic biomasses: Fractal kinetic modelling

Enzymatic hydrolysis of three pre-treated lignocellulosic biomasses -LCB- (wheat straw-WS-, corn stover-CSV- and cardoon stems -CS-) is studied. These biomasses were pre-treated by two methods: diluted sulfuric acid and acid ethanol-water extraction at six severity levels (H values). Pretreated solid fractions were hydrolyzed with commercial enzyme cocktails at standard conditions. A first-order kinetic fractal model was fitted to the experimental results. This model accurately describes the hydrolysis of all biomasses at all pre-treatment conditions studied. The results show that the formal first-order kinetic constant k depends on the biomass nature. The hydrolysis rate increases as the pre-treatment severity does, while the fractal exponent value h decreases. With these pre-treatments, and in terms of k and h, WS is highly reactive and, at medium H with EW pretreatment, highly accessible; CSV has a low reactivity and high accessibility and CS has the lowest reactivity and an increasing accessibility as severity rises.

Lignocellulose Pretreatment Combining Continuous Alkaline Single-Screw Extrusion and Ultrasonication to Enhance Biosugar Production

Pretreatment to improve the enzymatic digestibility of highly crystallized lignocellulosic biomass is essential in biorefinery processes. This study investigates the combination of lignocellulose pretreatment with continuous alkaline single-screw extrusion and ultrasonication for biosugar production. Miscanthus sacchariflorus was used because it is a promising bioenergy crop. The results show that ultrasonication with continuous alkaline pretreatment increased the enzymatic digestibility of carbohydrates and reduced the use of chemicals during pretreatment. An hour of ultrasonication following 0.2 M NaOH (2.25 mol-NaOH/kg-biomass) continuous alkaline pretreatment resulted in a 6.7% increase in total biosugar production (83.1% of theoretical yield), a decrease of up to 26.1% in chemical usage, and a 17.0% increase in lignin removal compared with the case without ultrasonication. The developed method can be considered an effective and eco-friendly approach to the production of bio-based materials.

Anaerobic co-digestion of cattle manure and liquid fraction of digestate (LFD) pretreated corn stover: Pretreatment process optimization and evolution of microbial community structure

Liquid fraction of digestate (LFD) was used to pretreat corn stover to enhance the biomethane production of anaerobic co-digestion (AcoD) with cattle manure. The effects of LFD concentration and water content (WC) for pretreatment on co-digestion performance and microbial community structure were investigated in a batch system. Results showed that the cumulative biomethane yield (CBY) for co-digestion was improved by 16.85%-41.78% compared with the control. The highest biomethane yield of 238.25 mL g VS^-1 was obtained at 85% WC for pretreatment and a 5 M LFD concentration, and this yield was 41.78% higher than that in the control. The LFD pretreatment enriched the dominant bacterial phyla (Firmicutes and Bacteroidetes), but had little influence on the prevalent archaeal genus (Euryarchaeota). This study demonstrated that LFD pretreatment can greatly enhance the biomethane yield of co-digestion of corn stover and cattle manure under optimal parameters.