Monika Marchwicka

The crystalline structure of cellulose plays a crucial role in its reactivity, which is particularly important in biomass processing involving enzymatic hydrolysis. This study investigates the effect of low-frequency ultrasound (40 kHz) on the efficiency of enzymatic hydrolysis of cellulose in poplar wood and its structure, with a focus on its crystallinity and susceptibility to enzymatic hydrolysis. Two experimental pathways were explored: ultrasound-assisted hydrolysis of raw wood and isolated cellulose. Structural modifications were assessed using Fourier-transform infrared spectroscopy to determine the Lateral Order Index (LOI) and Total Crystallinity Index (TCI), providing insight into the reorganisation of cellulose microstructure. To evaluate hydrolysis efficiency, glucose yields were quantified by high-performance liquid chromatography. The application of ultrasound to raw wood resulted in minimal improvement in sugar release, whereas pretreatment of extracted cellulose led to a modest acceleration of enzymatic hydrolysis. The results show that ultrasound-assisted hydrolysis of raw wood did not significantly increase glucose yield, reaching only 9.9 ± 0.3% and 10.1 ± 0.8% for two poplar hybrids. Only slight increases in TCI and no significant changes in LOI were observed after 4 h of ultrasonic exposure. It indicates limited disruption of the crystalline structure under the tested conditions.

An investigation of the effect of intense Hot Water Extraction (HWE) on the chemical properties and processability of shredded hemp stalks (Cannabis sativa L.) is presented in this study. The chemical composition of untreated hemp was compared to that of hemp subjected to V and XV successive HWE cycles. This study investigated changes in selected chemical compounds, such as extractives, lignin, cellulose, ash, and monosaccharides such as glucose and xylose. Additionally, post-HWE liquids were analyzed. Lignin content was determined by the UV–VIS spectrophotometry method, whereas monosaccharides (glucose, xylose) and inhibitors (formic acid, acetic acid, levulinic acid, ethanol, 5-(hydroxymethyl)furfural, and furfural) were identified by HPLC. Extractives and ash were effectively removed by the HWE process, decreasing from 3.2 to 2.0% and from 3.9% to 2.7%, respectively. The reduction in acid-soluble lignin was an important finding, indicating a selective modification of the lignin matrix. By the end of V cycles, xylose content in the liquid phase significantly increased from 117.9% to 19.4%, indicating a reduction in hemicelluloses. The cellulose content of the solid material rose from 42.9% to 46.2% at the end of XV cycles.

Due to the growing demand for biofuels and the importance of efficient utilization of lignocellulosic biomass, this study investigated the effect of different pre-treatment methods of poplar wood on the efficiency of enzymatic hydrolysis. Populus deltoides × maximowiczii wood aged 3 and 5 years, and P. trichocarpa wood aged 3 years were analysed. The first pre-treatment method involved mechanical size-reduction of the material into various particle fractions. The second pre-treatment method involved multiple extractions with water, ethanol, cyclohexane, a chloroform–ethanol mixture (93:7w/w), and a sequence of solvents (water–ethanol–cyclohexane). Afterwards, the pre-treated material was subjected to enzymatic hydrolysis, and HPLC was used to determine the glucose content in the hydrolysate. The results showed that the removal of extractives did not significantly affect glucose yield, suggesting that these compounds neither inhibit enzymatic activity nor limit access to cellulose. It was also observed that mechanical grinding of poplar wood caused a slight increase in glucose yield (up to approximately 20%) only for the smallest particle-size fraction (<0.16 mm). Despite this improvement, the process is economically limited and can serve only as a preliminary stage in further wood processing.

The present study aimed to determine the effect of material modification by hot water extraction (HWE) on the compaction efficiency of shredded Miscanthus giganteus stalks in the pellet production process. Samples were prepared to differ in the number of HWE cycles: HWE I was subjected to a single cycle, HWE II was subjected to two cycles, and HWE III was subjected to three cycles and unmodified material. An analysis of the compaction process was carried out to evaluate the effect of HWE on density and energy consumption. In this study, HWE pre-treatment was applied to improve biomass compaction efficiency and material properties, improving biofuel production’s sustainability and efficiency. A small change was found in glucose and xylose content, suggesting that HWE slightly affects these sugars. It was found that HWE significantly increased the density of compacted Miscanthus giganteus biomass, with a peak density of 388.7 kg·m⁻³ after the first HWE cycle. Ash content was reduced by 50% after one HWE cycle, making the biomass more suitable for biofuel applications. Furthermore, pretreatment with HWE reduced energy consumption during compaction, enhancing process efficiency. This study highlights the role of hot water extraction (HWE) in improving miscanthus compaction, enhancing density, reducing ash, and lowering energy use.

In this paper 1% NaOH extraction and 1% NaOH extraction with α-amylase pre-treatment were conducted on wheat and rye bran. Different times of reaction (0.5, 1, 2 and 4 h) and different temperatures (40C, 45C, 50C and 95C) of process were applied during experiments. After the process, dry residue content was calculated. Additionally, monosaccharides content in liquid was determined after α-amylase pre-treatment and 1% NaOH extraction. Monosaccharides content (glucose, xylose and arabinose) after acid hydrolysis of obtained liquids was determined by the HPLC technique. Obtained results showed that there was a positive correlation between time, temperature and content of compounds extracted by 1% NaOH solution. The lowest dry residue content for wheat and rye bran after 1% NaOH extraction was obtained at 95 C during 4 hours of conducting the process (24.70.1 and 18.42.8 respectively). Additional pre-treatment by α-amylase increased solubility of compounds included in bran, especially for wheat bran. α-amylase influenced not only starch solubility but also other compounds from bran. The next advantage of pre-treatment by α-amylase was easier access to remaining sugars inside the bran, which in the form of xylose and arabinose can be obtained.

Production of biofuel from lignocellulosic biomass is relatively low due to the limited knowledge about natural cell wall loosening and cellulolytic processes in plants. Industrial separation of cellulose fiber mass from lignin, its saccharification and alcoholic fermentation is still cost-ineffective and environmentally unfriendly. Assuming that the green transformation is inevitable and that new sources of raw materials for biofuels are needed, we decided to study cell death—a natural process occurring in plants in the context of reducing the recalcitrance of lignocellulose for the production of second-generation bioethanol. “Members of the enzyme families responsible for lysigenous aerenchyma formation were identified during the root hypoxia stress in Arabidopsis thaliana cell death mutants. The cell death regulatory genes, LESION SIMULATING DISEASE 1 (LSD1), PHYTOALEXIN DEFICIENT 4 (PAD4) and ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) conditionally regulate the cell wall when suppressed in transgenic aspen. During four years of growth in the field, the following effects were observed: lignin content was reduced, the cellulose fiber polymerization degree increased and the growth itself was unaffected. The wood of transgenic trees was more efficient as a substrate for saccharification, alcoholic fermentation and bioethanol production. The presented results may trigger the development of novel biotechnologies in the biofuel industry.

Production of biofuel from lignocellulosic biomass is relatively low due to the limited knowledge about natural cell wall loosening and cellulolytic processes in plants. Industrial separation of cellulose fiber mass from lignin, its saccharification and alcoholic fermentation is still cost-ineffective and environmental unfriendly. Assuming that the green transformation is inevitable and that the new sources of raw materials for biofuels are needed, we decided to study cell death - a natural process occurring in plants in a context of reducing the recalcitrance of lignocellulose for production of second generation bioethanol. “members of the enzyme families responsible for lysigenous aerenchyma formation were identified during the root hypoxia stress in Arabidopsis thaliana cell death mutants. The cell death regulatory genes, LESION SIMULATING DISEASE 1 (LSD1), PHYTOALEXIN DEFICIENT 4 (PAD4) and ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) conditionally regulate the cell wall when suppressed in transgenic aspen. During four years of growth in the field the following effects were observed: lignin content was reduced, the cellulose fiber polymerization degree increased and the growth itself was unaffected. The wood of transgenic trees was more efficient as a substrate for saccharification, alcoholic fermentation and bioethanol production. The presented results may trigger the development of novel biotechnologies in the biofuel industry.

The aim of this study was to investigate the effect of storing methods of woodchips from two species, pine (Pinus sylvestris L.) and alder (Alnus Mill.), on the basic chemical composition and sugar yield in liquid biofuel production. Two methods of storing woody biomass were used in the study—an open pile and a cover pile. The wood was felled at the end of November and was stored as industrial chips for eight months from December onward. After this time, material was collected for chemical composition analyses and enzymatic hydrolysis. The results of the chemical composition analysis of the wood for both studied species showed the influence of the type of storage on the composition of the individual structural components of the wood. Based on the results of the enzymatic hydrolysis of the woody biomass, it can be seen that, irrespective of the hydrolysed material (wood, cellulose, holocellulose), the material from the biomass stored in the open pile gave higher results. The hydrolysis efficiency also increased with time, independent of the type of material that was hydrolysed. The highest sugar yield from the enzymatic hydrolysis of wood was obtained for alder wood stored in an open pile. The highest sugar yield from the enzymatic hydrolysis of cellulose was obtained for cellulose extracted from alder wood—as well—that had been stored in an open pile.

The aim of the study was to determine the selected surface and physical properties of iroko (Milicia excelsa (Welw.) C.C. Berg) and tauari (Couratari spp.) wood after thermo-mechanical treatment (TMT) in relation to extractive content. During TMT, no chemicals are introduced into the wood, which distinguishes this method from a number of wood modification methods. The iroko and tauari wood were subjected to volumetric densification in a hydraulic press. The wood was densified in a radial direction at a temperature of 100 and 150 °C. The wood color parameters were measured using the mathematical CIE L*a*b* and L*C*h color space models. The roughness parameters of Ra and Rz parallel and perpendicular to the grain were investigated. The contact angle (CA) of the wood with distilled water was determined based on the sessile drop method. The equilibrium moisture content (EMC) and dimensional changes of the wood were determined for a climate with a temperature of 20 °C and a relative humidity (RH) of 9%, 34%, 55%, 75% and 98%. The tauari wood was less prone to color changes under the influence of TMT than the iroko wood. After densification, the iroko and tauari wood displayed a different character of roughness changes. The iroko wood featured the lowest level of roughness after TMT at 100 °C, and the tauari wood after TMT at 150 °C. The densified iroko and tauari wood were characterized by weaker dynamics in the changes in their respective contact angles than the non-densified wood. The higher the temperature of the TMT, the lower the EMC of the wood. Higher EMC values were observed for the tauari wood than for the iroko wood. This was due to the lower content of chloroform-ethanol extractives. Similar dependencies were obtained in the case of hot water extractives. The thermo-mechanically treated wood displayed a greater tendency towards dimensional changes in a climate with high relative air humidity, i.e., above 70%, compared to the non-modified wood.