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    Item type:Publication, Access status: with files ,
    Deep eutectic solvent pre-treatment of residual biomass streams – Effects on anaerobic degradability
    (Elsevier, 2025-08-15) ; ; ; ;
    Cam, Miyase Deniz
    The suitability of residual biomass from biorefineries as biogas substrate, including the effect of DES pre-treatment on biogas potential and biomass composition was evaluated. Three different biomasses, i.e., cork dust, olive tree pruning, and common reed, were treated with a deep eutectic solvent (DES; i.e., choline chloride and formic acid, 1:2 M ratio, 1:10 (g mL−1) solid to solvent ratio) under various conditions. While being ineffective under less severe conditions, significantly increased biogas potentials were observed for all biomasses at 130 °C and 40 and/or 60 min of pre-treatment. Cork dust had the highest relative increase in biogas potential of 125 % (130 °C, 60 min). With an increase of 90 mLN gVS−1 (+21 %), olive tree pruning showed the highest absolute increase. Common reed demonstrated a notable increase of 12 %. Concurrently, kinetic modelling revealed shifts in degradation kinetics, such as altered lag phases and higher maximum biogas rates, hereby the Cone Model provided the best fit for the data. The change could be attributed to delignification and retention of the fermentable glucan fraction in the solid biomass. Despite considerable differences among the biomasses, the results underscore the efficacy of DES pre-treatment in enhancing the anaerobic degradability of residual biomass.
    Publicationtype: Journal Article
      32  23
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    Deep eutectic solvent pretreatment of cork dust : effects on biomass composition, phenolic extraction and anaerobic degradability
    (Elsevier, 2024-05-30) ; ; ; ;
    Aslanhan, Dicle Delal
    In this study, phenolic compounds using deep eutectic solvents (DES) were extracted from cork dust, and the biogas production potential of DES-treated cork dust samples was determined. The DES treatment was carried out using choline chloride and formic acid (1:2 M ratio) at various temperatures (90, 110 and 130 °C) and treatment times (20, 40 and 60 min) at a solid-to-solvent ratio of 1:10 g mL−1. The highest total phenolic content (137 mg gallic acid equivalent (GAE) g−1 dry cork dust) was achieved at 110 °C/20 min. The extracts exhibited an antioxidant capacity of up to 56.3 ± 3.1 % 1,1-diphenyl-2-picrylhydazyl (DPPH) inhibition at a dilution rate of 100. DES treatment resulted in minimal sugar solubilization at low temperatures, while approximately 42 % of the xylan fraction in the biomass degraded under severe conditions (e.g., 130 °C/60 min). Catechin, 4-hydroxybenzoic acid and gallic acid were the major phenolics in DES extracts. The biogas yield of DES-treated cork dust increased with treatment severity. The highest biogas yield (115.1 mLN gVS-1) was observed at 130 °C/60 min, representing an increase of 125 % compared to the untreated sample. SEM images revealed that the surface structure of the samples became smoother after mild pretreatment and rougher after harsh pretreatment. Compositional and FTIR analyses indicated that a higher biogas formation potential was associated with increased cellulose content in the substrate, which could be attributed to hemicellulose solubilization in the hydrolysate. Overall, DES pretreatment effectively enhanced phenol extraction and anaerobic degradability.
    Publicationtype: Journal Article
      28
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    Item type:Publication, Access status: with files ,
    Deep eutectic solvent pre-treatment of residual biomass streams : effects on anaerobic degradability
    Deep eutectic solvent pre-treatment of residual biomass streams – effects on anaerobic degradability
    Publicationtype: Conference Presentation
      36  23
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    Item type:Publication,
    Effect of microwave-assisted deep eutectic solvent pretreatment on lignocellulosic structure and bioconversion of wheat straw
    In this study, it was aimed to investigate the efficacy of microwave assisted deep eutectic solvent (MW-DES) pretreatment on the structure of wheat straw as well as the sugar and ethanol yields. The samples were treated with choline chloride: formic acid at different mole ratios (1:2, 1:3, and 1:4), microwave power (270, 360, and 450 W) and pretreatment time (2, 5, and 8 min). MW-DES pretreatment has a significant impact on lignocellulosic structure, which was also verified by XRD and SEM analysis. It was found that xylan is the most affected constituent of biomass during MW-DES pretreatment. Severe conditions can solubilize up to 90% of the xylan into liquid phase. The removal of xylan and lignin during MW-DES pretreatment led to highly digestible and fermentable wheat straw fibers. Enzymatic hydrolysis of pretreated wheat straw fibers revealed that MW-DES pretreatment was vastly effective at achieving very high sugar yields (99% glucose, 85% xylose yield). A linear correlation between xylan removal and glucose release during enzymatic hydrolysis was observed. The maximum total sugar release (619 mg/g pretreated wheat straw fibers) being twice as much of conventional deep eutectic solvent (DES) pretreatment, was observed at 1:3 mol ratio, 360 W microwave power and 8 min retention time. The theoretical ethanol yield using Escherichia coli KO11 was 81.5%.
    Publicationtype: Journal Article
      131