Low Lignin Content Research Articles

Effect of a low seed lignin content on seed yield and quality in winter oilseed rape (Brassica napus)

AbstractIncreasing demand for vegetable oil and protein requires breeding efforts to enhance the yield of oilseed rape. This can be achieved by reducing seed cellulose, hemicellulose and lignin content. The objective of the study was to analyse seed yield and important agronomic traits of two distinct bulks of genotypes from two crosses, with low (6%) and high seed lignin content (10%). The two genotype bulks were formed by mixing seeds of 12 doubled haploid lines with either low or high lignin content. The genotypes were selected from two large doubled haploid populations based on lignin content, flowering time and plant height. The bulks were field‐tested in replicated yield trials. Seed quality analysis confirmed significant differences in seed lignin content between the two bulks. Seed oil content was moderately higher in the low lignin bulks of both crosses. Seed, oil and protein yield in both crosses were moderately to significantly higher in the low lignin bulks. Further breeding for reduced fibre content will help increase seed oil and protein content.

Lignin as a High-Value Bioaditive in 3D-DLP Printable Acrylic Resins and Polyaniline Conductive Composite.

With increasing environmental awareness, lignin will play a key role in the transition from the traditional materials industry towards sustainability and Industry 4.0, boosting the development of functional eco-friendly composites for future electronic devices. In this work, a detailed study of the effect of unmodified lignin on 3D printed light-curable acrylic composites was performed up to 4 wt.%. Lignin ratios below 3 wt.% could be easily and reproducibly printed on a digital light processing (DLP) printer, maintaining the flexibility and thermal stability of the pristine resin. These low lignin contents lead to 3D printed composites with smoother surfaces, improved hardness (Shore A increase ~5%), and higher wettability (contact angles decrease ~19.5%). Finally, 1 wt.% lignin was added into 3D printed acrylic resins containing 5 wt.% p-toluensulfonic doped polyaniline (pTSA-PANI). The lignin/pTSA-PANI/acrylic composite showed a clear improvement in the dispersion of the conductive filler, reducing the average surface roughness (Ra) by 61% and increasing the electrical conductivity by an order of magnitude (up to 10−6 S cm−1) compared to lignin free PANI composites. Thus, incorporating organosolv lignin from wood industry wastes as raw material into 3D printed photocurable resins represents a simple, low-cost potential application for the design of novel high-valued, bio-based products.

Multifunctional lignin-poly (lactic acid) biocomposites for packaging applications.

Lignin is the most abundant aromatic biopolymer with many promising features but also shortcomings as a filler in polymer blends. The main objective of this work was to improve the processability and compatibility of lignin with poly (lactic acid) (PLA) through etherification of lignin. Commercial kraft lignin (KL) and oxypropylated kraft lignin (OPKL) were blended with PLA at different weight percentages (1, 5, 10, 20, and 40%) followed by injection molding. Low lignin contents between 1 and 10% generally had a favorable impact on mechanical strength and moduli as well as functional properties of the PLA-based composites. Unmodified lignin with free phenolic hydroxyl groups rendered the composites with antioxidant activity, as measured by radical scavenging and lipid peroxidation tests. Incorporating 5–10% of KL or OPKL improved the thermal stability of the composites within the 300–350°C region. DSC analysis showed that the glass transition temperature values were systematically decreased upon addition of KL and OPKL into PLA polymer. However, low lignin contents of 1 and 5% decreased the cold crystallization temperature of PLA. The composites of KL and OPKL with PLA exhibited good stabilities in the migration test, with values of 17 mg kg−1 and 23 mg kg−1 even at higher lignin content 40%, i.e., well below the limit defined in a European standard (60 mg kg−1). These results suggest oxypropylated lignin as a functional filler in PLA for safe and functional food packaging and antioxidant applications.

RESPONSE SURFACE METHODOLOGY FOR OPTIMIZATION OF PERACETIC ACID PRETREATMENT OF PULP TO REDUCE POLLUTANTS FROM BLEACHING EFFLUENT

Pulp bleaching processes emit many toxic substances. Peracetic acid (PAA) has been long recognized as an efficient bleaching agent for cellulose pulps. In the present study, 20 runs were conducted using response surface methodology (RSM) through central composite design for optimization of peracetic acid treatment of hardwood pulp, as a pretreatment step before applying conventional bleaching. Three factors, namely temperature (50-80 °C), time (0.5-2.0 h) and PAA dose (0.5-2.0%), were investigated to find out their impact on the kappa number, yield, brightness and viscosity of the pulp. The findings revealed that the peracetic acid dose of 1.0% at 80 °C for 1.0 h was the most suitable to obtain pulp of kappa number 10.2, yield of 96.87%, brightness of 43.6% ISO and viscosity of 11.7 cP. FTIR analysis revealed that the peracetic acid pretreatment of the pulp led to lower lignin content, compared to untreated pulp, but also reduced the bleaching effluent parameters, such as BOD, COD, TDS, color and AOX, by 43.0%, 55.7%, 31.9%, 51.4% and 51.1%, respectively.

EXPRESIÓN DIFERENCIAL DE GENES CesA Y LA RELACIÓN CON EL CONTENIDO DE FIBRA EN HENEQUÉN

<p><strong>Background:</strong> Cellulose synthase is a superfamily where genes involved in the synthesis of the primary and secondary cell wall and their relationship with plant fibers have been reported. In recent years, vegetable fiber has been the subject of considerable interest, due to its quality and the ability to be biodegradable, and it has been reported that the cellulose content is related to the quality of the fiber. <strong>Objective:</strong> To determine the relationship of <em>CesA</em> genes with fiber content in <em>Agave fourcroydes</em> Lem. <strong>Methodology:</strong> The relative expression of the <em>CesA3, CesA4</em> and <em>CesA5</em> genes involved in the primary and secondary cell wall will be prolonged and their relationship with fiber content will be evaluated in plants of different heights in a henequen plantation. The content of the fiber components was evaluated using the TAPPI methods and an analysis of variance (ANOVA) was performed, the means were compared using the Tukey test (p≤ 0.05). <strong>Results:</strong> Plants with greater height, have longer leaves, with higher cellulose content (48%) and low content of hemicellulose (3%) and lignin (8%), these characteristics are related to high levels of relative expression of the <em>CesA3</em> and <em>CesA4</em> genes and low relative expression level of the <em>CesA5</em> gene. <strong>Implications:</strong> A direct connection of higher expression of <em>CesA3</em> and <em>CesA4</em> genes with the length of the leaves, the height of the plant and the cellulose content is presented. <strong>Conclusions</strong>: In this research, the exploration between the expression and the length of the leaves serves as a basis for future research focused on the early selection of individuals with high cellulose content, which through plant tissue culture represents an option for genetic improvement for the benefit of crop producers.</p>

Evaluation of improved Brachiaria (syn. Urochloa) grass cultivars for adaptation and nutritive values

This study was undertaken in three experiments. The first experiment conducted to study adaptation and the nutritive value for the three varieties (Brachiaria decumbence cv. Basilisk, B. brizantha cvs. Xaraes, & B. brizantha cvs. Piatã) compared with Rhodes grass (Fine cut) and local Brachiaria, B. botuliform cv. Local, to evaluate DM. CP. CF. NDF.EE. Ash Moreover, Lignin contents. While the other two experiments are conducted for analysis of fresh and silage samples. For the fresh a sample was collected for shed drying in the Animal Nutrition Laboratory for a period of 28 days to establish a complete drying. As well, different sample was collected for fermentation as silage in the animal nutrition laboratory for 28 days, then shed dried, the samples were, then grinded, each well labeled and packed to avoid moisture transfer. The samples were taken to Central Animal Research Station at Kuku for the subsequent chemical analysis of the varieties under investigation. The present result revealed that when comparing the fresh samples and silage samples, there was a significant difference in chemical composition in (DM. CP., CF., EE, Ash and lignin). While there was no significant difference in NDF among the treatments.On the other hand, B. brizantha cvs. Xaraes, Piatã revealed a higher crude fiber on a fresh basis and medium lignin content among the treatments when made as silage.The DM showed significant differences in all treatments, local Brachiaria has a higher level of DM, CF, Ash and Lignin contents than other treatments. CP significantly showed a low-level content as silage and a high level of lignin.This study concluded that local Brachiaria has a high level of CP on a fresh basis followed by Rhodes grass and lower CP as silage. Rhodes grass and Brachiaria Decumbence showed a higher crude protein level and low lignin contents than all other grasses under investigation, being in silage form. Because of high crude protein (11.79%) and lower Lignin content were recommended as the best forage grass followed by Brachiaria basilisk and Brachiaria Xaraes to be used as animal feed silage during the dry season.

Aspartic proteases modulate programmed cell death and secondary cell wall synthesis during wood formation in poplar.

Programmed cell death (PCD) is essential for wood development in trees. However, the determination of crucial factors involved in xylem PCD of wood development is still lacking. Here, two Populus trichocarpa typical aspartic protease (AP) genes, AP17 and AP45, modulate xylem maturation, especially fibre PCD, during wood formation. AP17 and AP45 were dominantly expressed in the fibres of secondary xylem, as suggested by GUS expression in APpro::GUS transgenic plants. Cas9/gRNA-induced AP17 or AP45 mutants delayed secondary xylem fibre PCD, and ap17ap45 double mutants showed more serious defects. Conversely, AP17 overexpression caused premature PCD in secondary xylem fibres, indicating a positive modulation in wood fibre PCD. Loss of AP17 and AP45 did not alter wood fibre wall thickness, whereas the ap17ap45 mutants showed a low lignin content in wood. However, AP17 overexpression led to a significant decrease in wood fibre wall thickness and lignin content, revealing the involvement in secondary cell wall synthesis during wood formation. In addition, the ap17ap45 mutant and AP17 overexpression plants resulted in a significant increase in saccharification yield in wood. Overall, AP17 and AP45 are crucial modulators in xylem maturation during wood development, providing potential candidate genes for engineering lignocellulosic wood for biofuel utilization.

Valorizing prickly pear cladodes via methane-arrested anaerobic digestion for carboxylic acid production.

To address climate change, liquid biofuels are an essential alternative to fossil fuels, especially for transportation. The carboxylate platform uses methane-arrested anaerobic digestion (MAAD) to ferment biomass to carboxylic acids, which can be chemically converted to liquid fuels via the carboxylate platform. Most biomass sources require expensive pretreatments to remove lignin; however, prickly pear (Opuntia ficus-indica) cladodes have low lignin content and therefore do not require pretreatment. Furthermore, this sugar-rich feedstock is readily digested to high concentrations of carboxylic acids. At various substrate concentrations, batch MAAD of prickly pear cladodes yielded primarily acetic, butyric, and caproic acids. From these batch data, continuum particle distribution modeling (CPDM) simulated four-stage countercurrent digestion. At a non-acid volatile solid (NAVS) concentration of 100 g/Lliq , CPDM predicts a high total acid concentration of 93 g/L and conversion of 0.93 g NAVSdigested /NAVSfed at a volatile solid loading rate of 6g/(Lliq ·d) and liquid retention time of 35 days. Without chemical pretreatment, co-digestion, or in situ product removal, prickly pear produced high yields, biomass conversion, product concentration, and selectivity compared to previously studied lignocellulosic feedstocks.

Efficient Recovery of Lignin and Hemicelluloses from Kraft Black Liquor

Black liquor (BL) from kraft pulping industries contains a large fraction of lignin and hemicelluloses and their efficient separation can open up new possibilities for integrated biorefineries. In this work, lignin and hemicelluloses were separated from BL and concentrated BL (obtained by ultrafiltration), by precipitation using acidification and antisolvent precipitation method, respectively. For lignin precipitation, different organic acids, namely acetic, lactic and citric acid, were used and the yield and purity of the extracted lignin were compared with the lignin precipitated using inorganic acids, namely sulphuric and phosphoric acid. Among the organic acids, the highest yield of lignin (57.2%) was obtained by lactic acid, but the extract also contained the highest levels of inorganic impurities (9.2%). The extract obtained from acetic acid contained lower inorganic impurities and the lignin yield was 48.1%. The hemicellulose was extracted from BL liquor that was concentrated using the ZnObased PES mixed matrix ultrafiltration membrane, which was started by first separating lignin (at pH 3.5, 4 and 4.5) from it. The supernatants from the lignin precipitation process were used as a source of hemicellulose and this was precipitated by using acetone as an antisolvent. The highest hemicellulose yield (54.4%) was obtained from the supernatant with the lowest lignin content and highest acetone to supernatant ratio.
 Keywords: acidification, antisolvent precipitation, hemicelluloses, kraft black liquor, lignin

Unveiling the mechanisms of carbon conversion and loss in biochars derived from characteristic lignocellulosic biomass

The relationship between biomass components and carbon retention or loss in biochars is unclear. In this study, four characteristic feedstocks were pyrolyzed into biochar, and the conversion and stability of carbon in biochar were studied in detail. Thirteen kinds of ion fragments were detected by thermogravimetry - mass spectrometry (TG-MS), among which H2O, CO2 and CO were the main gas products. In addition, the presence of lignin slowed that the pyrolysis of biomass and produced more CO, which eventually led to more aromatic biochar. The carbon retention of lignin, cellulose and xylan during pyrolysis was 78.7 %, 41.7 % and 40.2 %, respectively. Carbon retention calculations showed that lignin was a major contributor to the formation of biochar (40.1–53.2 %). In the K2Cr2O7 oxidation experiment, the carbon stability of sunflower and cotton stalk char was relatively poor, which was consistent with the results of thermal stability. Spectral characterization analysis showed that biomass with low lignin content generated more unstable carbon during pyrolysis, which was more likely to be lost or converted in an oxidized environment. These findings are meaningful for guiding in biochars preparation and avoiding their environmental risks.

Ultrasonic treatment decreases Lyophyllum decastes fruiting body browning and affects energy metabolism

Lyophyllum decastes is a common mushroom that is prone to browning during prolonged storage. In this study, the effects of ultrasonic treatment on metabolic gene expression, enzyme activity, and metabolic compounds related to L. decastes browning were investigated. Treatment of the fruiting body at 35 kHz and 300 W for 10 min reduced the browning index of L. decastes by 21.0 % and increased the L* value by 11.1 %. Ultrasonic treatment of the fruiting body resulted in higher levels of total phenols, flavonoids, and 9 kinds of amino acid with catalase (CAT) and peroxidase (POD) activities maintained at high levels. Higher cytochrome c oxidase (CCO), succinate dehydrogenase (SDH), phosphofructokinase (PFK), and pyruvate kinase (PK) activities may be ascribed to increased antioxidant capacity. Moreover, ultrasonication retained higher adenosine triphosphate (ATP) concentrations with an increased energy charge, while there were lower levels of adenosine diphosphate (ADP) and reduced and oxidized nicotinamide adenine dinucleotide (NADH and NAD+), respectively. Meanwhile, lower lignin contents were observed, along with retarded polyphenol oxidase (PPO) and lipoxygenase (LOX) activities. Lower PPO activity reduced the fruiting body enzymatic browning rate through decreased expression of LdPpo1, LdPpo2, and LdPpo3 during storage at 4 °C for 16 days. This activity may be used to determine the effectiveness of ultrasonication.

Understanding the effects of cellulose fibers from various pre-treated barley straw on properties of aerogels

This article for the first time reports the effects of properties of cellulose fibers obtained from various pre-treatments on the properties of aerogels. Here, cellulose fibers with different properties were produced by pre-treating barley straw with three different pre-treatment methods: alkaline, dilute acid, and acidified glycerol at 100 °C for 2 h. The results showed that the difference in composition of fibers lead to the difference in properties of aerogels. The aerogel prepared from fibers with the highest cellulose content (80% from acidified glycerol) had the largest surface area of 49.5 m2/g, whereas the aerogel with the lowest lignin content (6% from alkaline) has the lowest density and highest porosity of 0.0274 g/cm3 and 98.17%, respectively. Also, it shows that aerogels prepared from cellulose fibers with higher hemicellulose content and porosity had higher adsorption capacity towards methylene blue, suggesting that hemicellulose content and porosity of aerogels govern the adsorption capacity via electrostatic attraction and pore-filling. All synthesized cellulose aerogel had the oil adsorption capacity up to 30 times of its own weight and excellent storage capacity. The oil was easily recovered via a mechanical approach. This suggests the cellulose aerogels can be used as oil-spillage clean-up.

Correlation between lignin content and syringyl-to-guaiacyl (S/G) ratio of Eucalyptus globulus wood

Abstract Eucalyptus globulus Labill is an important raw material for pulpwood for which low lignin content and high S/G ratios are important parameters. This work shows a highly significant positive and strong correlation between S/G ratio and acid-soluble lignin (ASL) content among E. globulus trees. Although significant, the negative correlation between the S/G ratio and Klason lignin is weak, and there is no correlation with total lignin content. The Klason residue has a lower S/G ratio than that of the original wood. This suggests that the contribution of the S units to the solubilisation of lignin in acidic conditions is not limited to the S units but also to the G units. This effect becomes more pronounced as the percentage of S units increases.

Roles of metal and acid sites in the reductive depolymerization of concentrated lignin over supported Pd catalysts

Lignin is a natural polymer contained in lignocellulose and is a potential feedstock for the production of phenolics or small aromatic molecules. However, lignin depolymerization is typically performed using low lignin concentrations and insufficiently active catalysts, which hinders industrial applications. To address this issue, we herein investigated the depolymerization of concentrated kraft lignin and oak-extracted organosolv lignin promoted by supported bifunctional metal (palladium)-acid catalysts and elucidated the roles of acid and metal sites. In addition to acid sites, which are known to be critical for lignin degradation, metal sites were found to be required to initiate lignin depolymerization. Palladium atoms promoted depolymerization even in the absence of acid sites, while acid site–promoted depolymerization required the presence of surface palladium atoms. Catalysts with bulk palladium particles were much more active than those with highly dispersed palladium particles, which suggested that efficient depolymerization required the bulky lignin polymer to be adsorbed on the palladium surface in a multidentate fashion. Thus, our work provides valuable insights into the mechanism of catalytic lignin depolymerization and paves the way to the industrial-scale application of this process.

Synthesis of Microcrystalline Cellulose at Several Variations in Alpha-Cellulose Hydrolysis Time from Oil Palm Empty Fruit Bunches by Microwave Pre-treatment

MCC was synthesized from alpha-cellulose from microwave pretreated OPEFB. This study aims to determine the effect of microwave pre-treatment on changes in the cellulose and lignin content of OPEFB fibers and to synthesize MCC from OPEFB alpha-cellulose pretreated with microwaves. The method used in this research is exploration with 4 hydrolysis time treatments (10, 20, 30 and 40 minutes) with 3 replications. The data analysis technique used is descriptive statistical analysis. From the results of the study obtained differences in the levels of cellulose and lignin of EFB fiber before and after microwave pre-treatment. OPEFB fiber that has been pretreated has a higher cellulose content and lower lignin content than without pre-treatment. The yield and brightness level of the synthesized MCC color were different in each treatment. MCC obtained from the hydrolysis of alpha-cellulose for 10 minutes using 45% H2SO4 had the highest yield of 31.22% and the brightest color. Meanwhile, the lowest MCC yield was found in the hydrolysis treatment of alpha-cellulose for 40 minutes, namely 25.37% with a low brightness level. Furthermore, the color and texture of the MCC obtained from the best treatment was the same as that of the commercial Avicel MCC.

Comparison of various delignification/desilication pre-treatments and indigenous fungal cellulase for improved hydrolysis of paddy straw.

The efficient removal of lignin and silica from paddy straw is essential for its volarization into biofuels and other value-added products. In this work, different chemical pre-treatments viz. acid/alkali, organosolv and deep eutectic solvents were carried out to assess the extent of delignification and desilication of paddy straw. Maximum lignin and silica removal of 96.08 and 95.51% was observed with two step acid (0.5% sulphuric acid) followed by alkali (4% sodium hydroxide) pre-treatment with significantly low total lignin (2.30%) and silica content (0.80%) of the treated straw residue. The treated straw residue contained significantly high holocellulose (91.65%), cellulose (75.01%) and hemicellulose content (16.64%). Among the four indigenous fungal isolates, Penicillium mallochii (JS17) cellulase showed better accessibility for the treated straw residue with maximum release of 504.18mgg-1 of reducing sugars and saccharification efficiency of 56.90%. The two-step acid/alkali pre-treatment of paddy straw was highly effective for removing lignin and silica from paddy straw, thereby, resulting in enhanced enzymatic accessibility of the substrate and more efficient hydrolysis of cellulose into fermentable sugars.

Optimization of Hemp Bast Microfiber Production Using Response Surface Modelling

Non-wood biomass is particularly attractive as a cellulose source because of the lower lignin content. However, optimal cellulose extraction conditions are required as lignin content varies between plant sources. Further, the use of organic acids in place of harsh mineral acids is of interest in “greening” the cellulose production process. This study sought to establish optimum parameters for the extraction of cellulose microfibers (CMFs) from hemp (Cannabis sativa) biomass, using maleic and formic acids. Hemp fibers were pre-treated in NaOH (4 wt%) and aqueous chlorite in acetate buffer before ultrasonic treatment to break down bundles. The CMFs produced were compared with those generated from sulfuric acid hydrolysis. Response surface methodology (RSM) was used to determine combinations of three processing conditions, including acid concentration (45–64%), hydrolysis time (30–90 min), and temperature (45–65 °C). A central composite design (RSM-CCD) model with 21 experimental runs was optimized using MODDE 13.1 software. The model suitably described the data (R2 = 0.99; R2adj = 0.96). Microfibers with an average width of 6.91 µm, crystallinity range 40–75%, and good thermal stability were produced. Crystallinity was influenced by all three factors. The optimal crystallinity predicted by the model was 83.21%, which could be achieved using formic acid 62 wt% formic acid, 36 min hydrolysis time, and 47 °C hydrolysis temperature. These conditions resulted in a crystallinity degree of 82%. These data suggest formic acid can be used as an alternative to sulfuric acid for synthesis of cellulose microfibers from biodegradable hemp waste fibers.

Utilization of Waste Banana Pseudostem for Paper Production via Organosolv Pulping

Banana (Musa sapientum) is a predominant fruit crop grown in Sri Lanka which occupies nearly 60,000 ha of land, accounting for 54% of the total fruit cultivation land utilization in the country. The banana tree has a ten months cycle to bear fruits and after its harvesting, the stems are thrown away and left to decay and rot. The waste produced by a single banana plant can make up to 80% of the total plant mass and it is estimated that 220 tons of post-harvest biomass wastes are produced per hectare annually. This has led to waste disposal problems and serious environmental issues. Management of such a vast amount of agricultural waste promotes the use of this biomass for value addition processes. In this research work, an organosolv process based on a mixture of formic acid, acetic acid, and water was adapted and optimized to pulp banana pseudostem fiber and investigate its potential, as a raw material for pulp and paper production through chemical, morphological and mechanical characterization. The global consumption of paper totals more than 400 million tons, cutting down about 7.2 billion trees each year to meet its demand for printing, packaging, and writing purposes. Therefore, the initiative in utilizing available banana waste as an alternative raw material for paper production could further offer a great potential in reducing the dependence on natural timbers, which in turn reduces the demand for global deforestation in the long run. Banana pseudostem fiber is characterized by a high cellulose content and a low lignin content, which is desirable for better pulp yield and papermaking properties. However, it has a high ash content and its interference in the recovery of black liquor was overcome with the selected pulping method. It resulted in a high pulp yield (48.2%) with a kappa number of 32.4. A shorter fiber length (1.12 mm) contributed to a highly uniform paper structure with a smooth surface. Furthermore, the pulp fibers showed an increased crystallinity and a higher slenderness ratio, which is favorable for paper making. The papers produced were heavier weight boards with a grammage of 272 g/m2 and showed higher tensile index (43.16 Nm/g) and tear index (2.08 mNm2/g) compared to other published non-wood fibers.
 Keywords: Banana pseudostem, Organosolv, Cellulose, Pulp, Lignin

Colonization and decomposition of litter produced by invasive Acacia dealbata and native tree species by stream microbial decomposers

Changes in forest composition and litter inputs to streams due to invasion by exotic tree species can affect the functioning of freshwater ecosystems. Acacia dealbata is an important invasive tree species in Mediterranean areas, and often replaces the native riparian vegetation. In this study, we assessed the chemical characteristics of three litter types produced by the invasive Ac. dealbata (leaflets, flowers and pods) and leaf litter produced by two native tree species with contrasting litter characteristics (Quercus robur and Alnus glutinosa). We then assessed litter decomposition and associated microbial activity (i.e., overall microbial metabolism as respiration, fungal growth as biomass accumulation, and reproduction by aquatic hyphomycetes as conidial production), and the aquatic hyphomycetes community structure, in laboratory microcosms. In general, Ac. dealbata pods supported lower microbial activity and decomposed slower than all other litter types, due to their low nutrient concentrations and high carbon:nutrients molar ratio. Alnus glutinosa leaf litter supported high microbial activity and decomposed fast, due to its relatively high nutrient concentrations, low carbon:nutrients molar ratios and low lignin concentration. Acacia dealbata leaflets and flowers and Q. robur leaf litter generally had similar microbial activity and decomposition rates, intermediate between those of Ac. dealbata pods and Al. glutinosa leaf litter, likely due to trade-offs between nutrient concentrations and concentrations of structural and secondary compound among litter types. Aquatic hyphomycetes community structure also differed among litter types. For instance, Ac. dealbata pods had the lowest species richness per sampling date, but due to high dissimilarity among replicates, total species richness over the incubation period was comparable to that of other litter types. The invasion of native riparian forests by Ac. dealbata can affect the quality of litter inputs into streams, potentially affecting the community structure and activity of microbial decomposers, thus altering the functioning of stream ecosystems.

Slow pyrolysis of flax straw biomass produced in Kazakhstan: Characterization of enhanced tar and high-quality biochar

In the present study, local flax straw waste biomass samples were studied for their physical and chemical characteristics using a thermogravimetric analyzer (TGA) and thermal properties. Thermochemical conversion of the flax straw samples was performed in an electrically heated horizontal tube furnace from 400 to 600℃. Thermal analysis of the flax straw biomass showed higher calorific value of 18.2 MJ/kg, cellulose (27.4 wt%) and hemicellulose (24.8 wt%) content and lower lignin content (21.2 wt%). Mass balance of pyrolysis products showed 40.3% for bio-oil fraction at temperature of 500 ℃, which resulted in a notable reduction in the biochar yield by 34.6% compared to biochar yield at temperature of 400 ℃. Pyrolysis of flax straw samples further shows a notable reduction in moisture, ash and fixed carbon by 4.4%, 2.9% and 11.4%, respectively. In addition, it was noted that the tar obtained from flax straw is mostly composed of phenolic components, while XRD analysis confirms the degradation of cellulose in biochar fraction. Due to the higher de-volatilization behavior, calorific value, cellulose and hemicellulose content, also lower lignin and ash content, flax straw biomass can be used as a promising feedstock for bioenergy production.