Decomposition Of Hemicellulose Research Articles

Thermal Behaviour, Chemical Composition and Morphological analysis ofCotton Stalk for Efficient Biochar Production

The escalating concern over air pollution from crop stubble burning necessitates responsible biomass disposal or utilisation. In this study, characterisation of cotton stalk was carried out to assess its feasibility for biochar production. The proximate analysis revealed that cotton stalk had moisture content of 8.65%, bulk density of 215.8 kg m-3, volatile matter of 71.65%, and fixed carbon content of 16.03%. The ultimate analysis showed that cotton stalks were predominantly composed of carbon (64.88%), hydrogen (6.58%) , and oxygen (2.55%), with a low (0.66%) nitrogen content . Thermo-gravimetric analysis (TGA) highlighted the pyrolysis process, identifying a peak temperature of approximately 500°C and distinct stages of thermal degradation: moisture loss up to 150°C, hemicellulose decomposition between 200°C and 300°C, cellulose decomposition from 300°C to 400°C, and lignin decomposition from 400°C to 500°C. X-ray diffraction (XRD) analysis confirmed the presence of crystalline cellulose with a diffraction peak at 2θ = 22.5°, indicating significant structural stability during pyrolysis for biochar production. Fourier-transform infrared (FTIR) spectroscopy revealed characteristic peaks associated with cellulose and lignin, underscoring the retention of essential structural components in biochar during biomass conversion. These analyses demonstrated the potential of cotton stalks as a viable feedstock for biochar production, providing a sustainable method for agricultural waste management and soil health improvement.

Bamboo durability: Understanding the combined effect of weathering and mildew infection

Bamboo has been widely used in outdoor applications and heat treatment is a typical industrial technique for improving its durability. Weathering and mildew are the two main types of deterioration that occur on bamboo. However, there are few studies on the deterioration of bamboo properties and degradation mechanism under such combined effect. Therefore, in this study, the effect of weathering on the mildew infection value (MIV) of natural bamboo (NB) and heat-treated bamboo (HB) were compared. The changes in surface color, morphology, and chemical composition of NB and HB during accelerated UV weathering were characterized. Meanwhile, the MIV of bamboo samples after different weathering durations was evaluated and the influencing mechanism was explored. The results revealed that the decomposition of starch and hemicellulose during heat treatment resulted in the generation of levoglucosan and acids, thereby providing a new nutrient source and a more suitable environment for mildew growth. HB exhibited superior color stability and anti-weathering characteristics compared to NB. Moreover, certain photodegradation products from HB demonstrated anti-fungal and anti-weathering properties, which resulted in a temporary resistance to mildew in weathered samples. However, after long-term exposure, the cracks on the surface of HB caused by weathering facilitated the colonization of mildew hypha by releasing inner nutrients, leading to severer mildew infection.

Transcriptomic analysis of the metabolic characteristics of Aspergillus oryzae during the fermentation of doenjang-meju, a traditional Korean fermented soybean brick

To investigate the fermentative traits of Aspergillus oryzae in doenjang-meju, a traditional Korean fermented soybean brick, we prepared doenjang-meju bricks inoculated with both A. oryzae and Bacillus velezensis––recognized as crucial microbes in doenjang-meju fermentation, and then the transcriptomes of A. oryzae were analyzed throughout the entire fermentation period. The transcriptomic analysis of carbohydrate-active enzyme (CAZy) genes revealed that A. oryzae exhibited robust expression of CAZy genes involved in the decomposition of various carbohydrates, particularly cellulose, starch, and hemicellulose, indicating the active breakdown of soybean carbohydrates by A. oryzae during fermentation. Furthermore, KEGG analysis, metabolic pathway reconstruction, and their transcriptomic analysis provided a comprehensive overview of the decomposition patterns of various carbohydrates, lipids, and proteins and the metabolic features of various carbon compounds during fermentation. Additionally, the transcriptomic analysis of biosynthetic gene clusters indicated the potential production of various secondary metabolites by A. oryzae during fermentation. Genes related to carbohydrate and carbon compound metabolisms and secondary metabolite biosynthesis displayed unique and different transcriptional expression patterns depending on the specific gene and fermentation stage. Overall, our findings provide comprehensive insights into the metabolic characteristics of A. oryzae, thus contributing to our understanding of soybean fermentation.

Improving dairy manure hydrolysis and acidification through microbial community restructuring by adaptation to hyperthermophilic conditions

Dairy manure (DM) contributes significantly to greenhouse gas emissions and ecosystem degradation, yet its resistance to biodegradation hinders widespread bioprocessing applications. Lignocellulosic materials in DM pose a particular challenge because of their recalcitrance. Bioprocessing under hyperthermophilic (≥70 °C) conditions potentially offers an advantage over traditional fermentation temperatures due to enhanced activity of enzymes and the kinetics of enzymatic reactions. This can lead to a higher conversion rate and a greater extent of biomass hydrolysis and acidification. To test the validity of this hypothesis, the current study evaluated the efficacy of anaerobic hydrolysis and acidogenic fermentation of DM under mesophilic, thermophilic, and hyperthermophilic conditions. All inocula were adapted to corresponding temperatures but were derived from the same mesophilic source. Hyperthermophilic conditions resulted in superior DM hydrolysis efficiency (53%) compared to mesophilic (34%) and thermophilic (42%) conditions. The hyperthermophilic environment was particularly favorable to the decomposition of crude proteins and hemicellulose, which were reduced by 64% and 54%, respectively. Furthermore, hyperthermophilic fermentation also yielded the highest volatile fatty acid (VFA) production rate of 460 mg/L/day during the first four days, representing improvements of 50% and 90% over mesophilic and thermophilic conditions. In part, this was attributed to the enhanced production of branched-chain VFAs, including an increase of 6–10% in isobutyric acid and 12–13% in isovaleric acid. At hyperthermophilic conditions, however, there was no accumulation of VFAs during the days 5–8 of fermentation, which could be due to acetate conversion by the syntrophic acetate-oxidizing bacteria. A considerable gain in hydrolysis efficiency and VFA production rate were accompanied by a reduction in microbial diversity, which suggests that hyperthermophilic temperature is a favorable environment for the selection of organisms with enhanced DM hydrolysis and fermentation capabilities. A significantly increased relative abundance of xylanolytic Caldicoprobacter (23% of population) and proteolytic Thermovirga (9% of population) could be the major contributors to improved decomposition of hemicellulose and protein. As revealed by the techno-economic analysis, acidogenic fermentation of DM at 70 °C and a retention period of 4 days provides the greatest positive net present value, highest internal rate of return of 9.2%, and shortest investment payback period of 9 years. This study demonstrates that hyperthermophilic conditions enable superior deconstruction and bioconversion of lignocellulose-containing biomass into VFAs under reduced retention times, offering a promising approach for improving DM management and generating bioproducts.

Effect of Microbial Degradation Treatments on Lignocellulose, Cellulose, and Water-Holding Capacity of Four Typical Forest Fuels from Northeast China

Since forest fuel decomposes slowly and increases the risk of forest fires by accumulating over the years, forest fuel management to accelerate the decomposition process is essential to prevent forest fires and protect forest resources. In this study, we conducted experiments on forest fuels (Pinus sylvestris var. mongholica, Larix gmelinii, Quercus mongolica and Fraxinus mandshurica) in four typical plantation forests in northeast China by adding Trichoderma spp. to investigate the decomposition process and the changes in cellulose, hemicellulose and the water-holding capacity of the fuels. The addition of Trichoderma spp. accelerated the decomposition of cellulose, hemicellulose and lignin in the fuel. Trichoderma spp. promoted the ratio of water absorption and loss, as well as the water-holding capacity of the fuels. The ratio of water absorption and loss reached equilibrium when the decomposition time was up to 35 days, and the addition of Trichoderma spp. increased the maximal water-holding capacity of the fuel. The residual ratio of the four types of fuel degraded by the different treatments was inversely proportional to their maximal water-holding capacities and to the residual ratios of cellulose, hemicellulose and lignin. The residual ratios of degradation of the four fuels under different treatments were linearly related to their maximum water-holding capacity, cellulose, hemicellulose and lignin residual ratios. Trichoderma spp. had a positive effect on the degradation effect and water-holding capacity of fuel on the ground surface of four typical plantation forests. The study is of positive significance for the decomposition of fuel in forests, it promotes the development of biological fire prevention technology and provides a basis for the reinforcement of the management of fuel in forests and the protection of forest resources.

A novel molecular structure parameter determination method for biomass thermochemical conversion mechanism investigation

The low-grade energy properties and high O content of biomass limit its efficient energy utilization. Torrefaction is known to be one of the most promising thermochemical conversion methods for upgrading biomass. 250 °C Gas-pressurized (GP) torrefaction realizes deep decomposition of hemicellulose in biomass to as high as 99.7% by deoxygenation and aromatization. However, the above thermochemical conversion mechanism at molecular-level is currently scant. Here, a novel molecular structural parameter method and pure hemicellulose torrefaction were employed to investigate the thermochemical conversion mechanism. Results demonstrate that O content of 250 °C GP torrefied hemicellulose was as low as 28.8 wt%, which was considerably lower than 44.6 wt% of traditional torrefied hemicellulose. There are five deoxygenation mechanisms of hemicellulose during the GP torrefaction: deacetylation, decarbonylation, dehydroxylation, ring opening and cyclization reactions to produce CO2/CH3COOH, CO, H2O, ketones/aldehydes and furans. The deoxygenation and aromatization reactions cause the chemical structure of hemicellulose evolution significantly, these mechanisms are: active hemicellulose undergo aromatization reaction through cyclization and deoxidation to generate preliminary 2-ring furans polymer, followed by stepwise polymerization reactions to form 4-ring and 6-ring furans polymers. These polymerization reactions further greatly enhance deoxygenation reaction. A thermochemical conversion mechanism model is developed based on the above investigation. This work provides a novel method for determining the molecular structure and reaction mechanism of thermochemical converted biomass.

Rapid humification of cotton stalk catalyzed by coal fly ash and its excellent cadmium passivation performance.

Due to industrialization, soil heavy metal pollution is a growing concern, with humic substances (HS) playing a pivotal role in soil passivation. To address the long duration of the compost humification problem, coal fly ash (CFA) in situ catalyzes the rapid pyrolysis of the cotton stalk (CS) to produce HS to address Cd passivation. Results indicate that the highest yield of humic acid (HA) (8.42%) and fulvic acid (FA) (1.36%) is obtained when the CS to CFA mass ratio is 1:0.5, at 275 ℃ for 120min. Further study reveals that CFA catalysis CS humification, through the creation of alkaline pyrolysis conditions, Fe2O3 can stimulate the protein and the decomposition of hemicellulose in CS, and then, through the Maillard and Sugar-amine condensation reaction synthesis HA and FA. Applying HS-CS&CFA in Cd-contaminated soil demonstrates a 26.69% reduction in exchangeable Cd within 30days by chemical complexation. Excellent maize growth effects and environmental benefits of HS products are the prerequisites for subsequent engineering applications. Similar industrial solid wastes, such as steel slag and red mud, rich in Fe2O3, can be explored to identify their catalytic humification effect. It could provide a novel and effective way for industrial solid wastes to be recycled for biomass humification and widely applied in remediating Cd-contaminated agricultural soil.

Kinetic, gas emission, reaction pathway and interaction mechanism analysis during oxidative pyrolysis of aluminium electrolysis waste with beech wood

The oxidative pyrolysis kinetic, gas emission, reaction pathway and interaction mechanism during oxidative pyrolysis of spent cathode carbon block (SCCB) and beech wood (BW) were investigated via the thermogravimetry combined with Fourier transform infrared spectrometer (TG-FTIR) analysis. The hemicellulose, cellulose, and lignin in BW and the carbon materials and fluoride in SCCB were determined as the main five components based on thermogravimetric experiment. Compared with pure SCCB, the addition of BW increased the comprehensive oxidative pyrolysis index. Furthermore, the total of 44 kinetic parameters were obtained by the Shuffled Complex Evolution (SCE) method, which were used to further forecast the mass loss of the above five main components. The evolved gases were detected by FTIR, and the results indicated that the main gases for BW/SCCB oxidative pyrolysis were CO2, which corresponded to the oxidation of cellulose, lignin and carbon materials. Small amounts of phenols, alcohols, ethers, ketones, aldehydes, carboxylic acids, CO, aromatics, alkene were attributed to the thermal decomposition of hemicellulose and cellulose. Pyrolysis of cellulose and lignin produced small quantities of hydrocarbons. HF was formed by the thermal decomposition of fluoride. Eventually, the reaction pathway was proposed and the possible interaction mechanism was analyzed during the oxidative pyrolysis of BW/SCCB blends.

Metagenomic insights into microbial variation and carbon cycling function in crop rotation systems

The decomposition and utilization of plant-derived carbon by microorganisms and carbon fixation are crucial pathways for enhancing soil organic carbon (SOC) storage. However, a gap remains in our understanding of the impact of microorganisms on the decomposition of plant-derived carbon and their capacity for carbon fixation in crop rotation systems. Based on a 12-year experiment with wheat–maize (WM), wheat–cotton (WC), and wheat–soybean (WS) rotations, the microbial communities and carbon cycle function were investigated. The results indicated that WS rotation significantly increased SOC content compared to WM and WC. In addition, a significant increase was observed in microbially available carbon and microbial biomass carbon in the WS soil compared with those in the others. Further analysis of the microbial community factors that influenced SOC content revealed that WS rotation, in contrast to WM rotation, enhanced the diversity and richness of bacteria and fungi. Analysis of microbial carbon decomposition functions revealed an increase in starch, lignin, and hemicellulose decomposition genes in the WS soil compared to the others. The changes in carbon decomposition genes were primarily attributed to six bacterial genera, namely Nocardioides, Agromyces, Microvirga, Skermanella, Anaeromyxobacter, and Arthrobacter, as well as four fungal genera, namely Dendryphion, Staphylotrichum, Apiotrichum, and Abortiporus, which were significantly influenced by the crop rotation systems. In addition, microbial carbon fixation-related genes such as ACAT, IDH1, GAPDH, rpiA, and rbcS were significantly enriched in WS. Species annotation of differential carbon fixation genes identified 18 genera that play a role in soil carbon fixation variation within the crop rotation systems. This study highlights the impact of crop rotation systems on SOC content and alterations in specific microbial communities on carbon cycle function.

Optimization of Torrefaction Parameters Using Metaheuristic Approach

The probabilistic technique was used to optimize the torrefaction parameters that indirectly influence the yield of end-products obtained through the pyrolysis of biomass. In the same pursuit, pine cones underwent thermal pre-treatment at 210 °C, 220 °C, 230 °C, 240 °C, and 250 °C in the presence of N2 gas with a flowing rate of 0.7 L∙s−1, whereas the duration of the pre-treatment process was 5 min, 10 min, and 15 min at each. To facilitate the processing of pine waste, a muffle furnace was improvised for pilot-scale testing. The thermal process used to carry out torrefaction was quasi-static. The average dynamic head of volatile gases inside the chamber was 1.04 m. The criteria for determining the optimal solution were based on calorific value, solid yield, energy consumption during the pre-treatment process, and ash handling. In absolute terms, time and temperature did not influence the statistical deviation in cellulose and hemicellulose decomposition after thermal pre-treatment. While considering ash content as a primal factor, thermal processing should be conducted for 5 min at 210 °C for the bounded operating conditions, which are similar to the operating conditions obtained experimentally. The optimal solid yield would be obtained if the thermal pre-treatment is performed at 250 °C for 5 min. The solution derived through a simulated annealing technique provided a better convergence with the experimental dataset.

Optimisation of microwave vacuum pyrolysis conversion of palm oil empty fruit bunches into biochar and bio-oil

The optimization of the production of Bio-oil and Biochar, from palm oil empty fruit bunches (POEFB) usually thrown as waste, was achieved using microwave vacuum pyrolysis, with expectations of it being a novel source of energy. Moreover, the demand for energy resources is perpetually increasing, due to the rapid increase in population and industrial developments. Surface response methodology via the central composite design was used to investigate the significance of microwave power (w), pyrolysis time (min) and absorbent / biomass ratio (g/g) on the yields in bio-oil and Biochar from POEFB. The optimal yield in bio-oil was 35.05 wt. %, obtained at 14.4 minutes, a ratio of 1: 24 and a power of 382 W and optimum yield in Biochar was 103.75 wt. %, obtained at 1.6 minutes, a ratio of 9:16 and power of 382 W. Thermogravimetric analysis showed the decomposition of hemicellulose at 300 °C, cellulose at 350 °C and lignin from 400 ° C. The greatest effect on the yield in bio-oil from POEFB, was time factor; meanwhile, for the yield in Biochar, the time and absorbent/biomass ratio had the greatest influence.

Conversion mechanism of pyrolysis humic substances of cotton stalks and carbide slag and its excellent repair performance in Cd-contaminated soil

Unlike traditional biomass composting humification, pyrolysis humification can rapidly convert waste biomass into humic substances (HSs) at lower temperatures and in an alkaline environment for soil remediation. This study utilized the strong alkaline solid waste carbide slag (CARBIDE) and cotton stalk (CS) for pyrolysis humification. The pyrolysis humification mechanism and effect of CARBIDE and CS were investigated using FT-IR, NMR, and Py-GC/MS. Furthermore, the ability of HSs to remediate cadmium-contaminated soil (Cd-soil) was assessed through soil property analysis, pot tests, and microbial diversity studies. The results showed that humic acid (HA) and fulvic acid (FA) had the highest yield of 19 % and 5 %, respectively, among the humic substances (HS-CS&CA) produced under the conditions of 250 ℃, reaction time of 2 h and mass ratio of CS to CARBIDE of 5: 1. At 250 ℃, CARBIDE changed the heat transfer mechanism of biomass, promoted the decomposition of more hemicellulose and protein, promoted the Deamination, Ketonization and Maillard reaction, and synthesized more HAs. HS-CS&CA had a significant remediation effect on Cd-soil. The immobilization rate of Cd was as high as 23 %, and the accumulation of Cd in maize was reduced by 65 %. At the same time, the relative abundance of beneficial bacteria such as Xanthomonadaceae and Bacillaceae for immobilizing Cd was increased, and the cycling effect of N and P was also enhanced. This study provides an innovative technical route for the rapid humification of CARBIDE and CS and its application in Cd-soil remediation.

Kinetic, products and shrinkage for the pyrolysis of flax fibers

Biomass pyrolysis is a thermochemical process used for renewable products and energies. However, there are still issues that need to be addressed for process modeling and optimization. This study focuses on the relationship between heating rate, shrinkage, and products from flax fibers using thermogravimetric analysis (TGA), microscopic observation, and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). TGA confirms sequential evaporation of water then decomposition of hemicellulose, cellulose, and lignin. Observations from the micro-reactor show that flax fibers undergo shrinkage within the temperature range of 335–370 ∘C, depending on the heating rate. Pyrolysis products were analyzed using Py-GC/MS at four different final temperatures from 350 to 500 ∘C, revealing the presence of anhydrosugars, furans, ketones, phenols, esters, alcohols, aldehydes, and acids. The results indicate a correlation between temperature and the increase in furans and ketones. The analysis suggests that furans and ketones are associated with shrinkage.

Genomic evidence for the widespread presence of GH45 cellulases among soil invertebrates.

Lignocellulose is a major component of vascular plant biomass. Its decomposition is crucial for the terrestrial carbon cycle. Microorganisms are considered primary decomposers, but evidence increases that some invertebrates may also decompose lignocellulose. We investigated the taxonomic distribution and evolutionary origins of GH45 hydrolases, important enzymes for the decomposition of cellulose and hemicellulose, in a collection of soil invertebrate genomes. We found that these genes are common in springtails and oribatid mites. Phylogenetic analysis revealed that cellulase genes were acquired early in the evolutionary history of these groups. Domain architectures and predicted 3D enzyme structures indicate that these cellulases are functional. Patterns of presence and absence of these genes across different lineages prompt further investigation into their evolutionary and ecological benefits. The ubiquity of cellulase genes suggests that soil invertebrates may play a role in lignocellulose decomposition, independently or in synergy with microorganisms. Understanding the ecological and evolutionary implications might be crucial for understanding soil food webs and the carbon cycle.

Maintaining the native gut microbiota of bharal (Pseudois nayaur) is crucial in ex situ conservation.

As wildlife protection continue to strengthen, research on the gut microbiota of wildlife is increasing. Carrying out conservation and research on endangered species in the Qinghai Tibet Plateau plays an important role in global biodiversity conservation. This study utilized 16S rRNA sequencing of fecal samples to investigate the composition, function, and changes of the gut microbiota of bharal in different environments, seasons, and genders. The results showed that Firmicutes and Bacteroidota were the dominant phyla and UCG-005, Bacteroides, UCG-010 were the dominant genera of bharal. In the wild, the abundance of Firmicutes increased which was conducive to the decomposition and utilization of cellulose, hemicellulose, and carbohydrate. Due to the variety of food types and nutrition in different seasons, the composition and function of gut microbiota were obviously different between genders. Compared with zoo, higher alpha diversity, a more complex gut microbiota network structure, and stronger metabolic function were conducive bharal to adapting to the wild environment. In the zoo, captive bharals were fed foods rich in high fat and protein, which increased the abundance of Bacteroidota and reduced the alpha diversity of gut microbiota. A fixed diet unified the gut microbiota between genders of bharal. It is very important to pay attention to the impact of captive environments and maintain the native gut microbiota of wildlife.

Drying Shrinkage and Mechanical Strength of Cementitious Composites with Alkali-Treated Makino Bamboo Fibers

ABSTRACT Alkali-treated bamboo fibers (AFs) treated with different NaOH concentrations (5 and 10%) and treatment times (1, 12, and 24 h) were used as fillers to fabricate cementitious composites with AFs (CAFs) in the present study. The results demonstrated that alkali treatment caused the partial decomposition of hemicellulose and lignin and an increase in the surface roughness of bamboo fibers. Additionally, the amounts of calcium hydroxide in alkali-treated CAFs were higher than in untreated CAFs, and they increased with increasing NaOH concentration and treatment time. For drying shrinkage (DS) under 75% relative humidity (RH), the DS values of the CAFs significantly decreased after adding AFs compared to the DS values of untreated CAFs. Compared to untreated CAFs, the density of the 5% and 10% NaOH-treated CAFs with longer treatment times decreased by 2.9% and 5.1%, respectively. Furthermore, the tensile strength of all alkali-treated CAFs exhibited no significant differences when compared with that of untreated CAFs, while the modulus of rupture and compressive strength were significantly decreased by NaOH treatment. These results indicated that the AFs significantly improved the drying shrinkage of the CAFs and hydration retardation effect of cement pastes, while the density and mechanical strength of the CAFs decreased.

Interaction among lignocellulosic biomass components in thermochemical processes

This research aims to evaluate the thermal behavior of main components of biomass (hemicellulose, cellulose and lignin) in order to identify their synergistic effect in thermochemical processes. These components were isolated from sugarcane bagasse and straw using different chemical treatments and their chemical and physical-chemical characterizations were performed. Results showed that chemical treatments were adequate for cellulose and lignin isolation, although it was verified that more adequate methodologies must be sought for hemicellulose isolation. The thermogravimetric analysis of each sample and their mixtures in inert (N2) and oxidant (synthetic air) atmospheres allowed investigating the synergism among the components. It was observed that the synergistic effect was more pronounced in DTG curves in an oxidizing atmosphere. There was a weak interaction effect between cellulose and hemicellulose, but hemicellulose allowed reducing cellulose decomposition rate. Moreover, the mixture between hemicellulose and lignin showed a synergistic effect on lignin, which promoted an increase in hemicellulose decomposition rate, while hemicellulose anticipated the main event of lignin decomposition in an oxidizing atmosphere. It was found that lignin had a positive effect on cellulose decomposition in an oxidizing atmosphere, thus inhibiting its decomposition, while cellulose promoted an increase in lignin decomposition rate in its final event. Ultimately, results for the synergistic effect allowed detecting other components besides isolated elements in the biomass structure in smaller amounts, which nevertheless affect the behavior of its thermal decomposition.

Synergistic effects of the mixing factor on the kinetics and products obtained by co-pyrolysis of Rosa rubiginosa rosehip seed and husk wastes

The aim of this work was to study the potential synergistic effects of the mixing factor on the kinetics parameters and products obtained through co-pyrolysis of two wastes from Rosa rubiginosa rosehip, and further co-gasification with CO2 of the remaining biochar. Thermogravimetric analysis showed that 6 different processes occur by slow pyrolysis (heating rates of 5, 10, and 20 °C/min), associated with the decomposition of hemicelluloses, cellulose, lignin, and CaCO3 from the ashes. Isoconversional methods determined activation energies of 84.68–223.42, 230.11–270.85, 187.58–303.37, and 400.11–421.71 kJ/mol for hemicellulose, cellulose, lignin, and CaCO3 decomposition, respectively. In most cases, the activation energy from co-pyrolysis was higher for the blends than for the pure wastes, which means that the blends are less reactive to pyrolysis. Gas and tar analyses showed that the blend with 75 % husk waste and 25 % seed waste produced the most hydrogen (5.639 mmol/g biomass), while the blend with 25 % husk waste and 75 % seed waste produced the most carbon monoxide (3.642 mmol/g biomass). The biochar produced by the blends and pure wastes were thermally treated with CO2 to compare reactivity to gasification. It was concluded that the addition of husk waste to the blend increases the reactivity of the biochar obtained, mainly due to its higher ash content.

Devolatilization characteristics of a bio-residue (potato stems) with high contents of alkali metals and non-structural components – Influences of the washing pretreatment severity

A bio-residue (potato stems), rich in alkali metals and non-structural components, is subjected to hot (353 K) or acidic (0.1 mol/L hydrochloric acid) water washing. The acidic pretreatment is more effective for the demineralization, with alkalis reduced by 99 (powders) or 90 (particles) %, corresponding to organic matter dissolution around 35 or 17 wt%, respectively. The latter figures remain approximately the same for hot water washing (38 and 19 wt%) but alkalis are reduced only by 78 or 64 %. The leachate properties are significantly dependent on the solvent type and the residue granulometry, as indicated by thermogravimetric and SEM-EDX analysis. Washed bio-residues decompose at temperatures and with rates progressively increasing as the pretreatment becomes more severe (fine granulometry and acidic water washing). Multi-step global kinetics, previously developed for the untreated material and properly revisited to incorporate washing effects, reveals trends with important compositional changes. Despite starch dissolution, volatile product yields for the absolute peak rate zone increase by about 40–65 %, testifying augmented cellulose contents. The pectin compounds are almost eliminated, to the advantage of the shoulder rate zone, representing hemicellulose decomposition, with an increase in the volatile product yields around 22–78 %.

Effects of different heat treatment media on odorous constituents, chemical decomposition and mechanical properties of two hardwoods.

With China's increasing dependence on foreign wood, African wood has gradually become a potential imported species, but its use is seriously affected by problems such as unpleasant odors. In this study, we investigate the effect of heat treatment medium on odor-causing VOCs, decomposition of structural polymers, Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) of hardwood. Samples of "Afrormosia" and "Newtonia" wood were heated under air and palm oil for two hours at 160 °C, 180 °C, and 200 °C, respectively. Then, the nature of the odor of each VOC emitted by the wood before and after heat treatment was identified using the GCMS method. The decomposition of hemicelluloses, cellulose and lignin in wood samples was examined using a ThermoGravimetric Analyzer coupled to Fourier Transform InfraRed spectrometry (TGA-FTIR). The 3-point bending test was used to evaluate MOR and MOE. The results indicate that the main VOCs responsible for unpleasant smells are acetic acid and hexanal; the reduction in hexanal emissions after heat treatment is mainly due to the treatment temperature, while the reduction in acetic acid emissions depends on the heat treatment medium and is due to the chemical interactions between palm oil and acetic acid; thus, the heat treatment under palm oil reduces the percentage area of VOCs with unpleasant odors in Afrormosia and Newtonia wood better than the heat treatment under air. Based on TGA-3D FTIR analysis and mechanical results, the reduction in MOR is greater in heat treatment under air because the said treatment induces a greater loss of woody matter, which was characterized by higher H2O and CO emissions during heat treatment of wood under palm oil than during heat treatment of wood under air. On the other hand, palm oil more than air, promotes lignin deacetylation, which is characterized by the fact that the 1050 cm-1 wavelength peak was far higher in samples treated with palm oil than in those treated under air; and this might explain why heat treatment under palm oil reduces MOE more than heat treatment under air.