Lignin Decomposition Research Articles

Complete genome sequences and comparative secretomic analysis for the industrially cultivated edible mushroom Lyophyllum decastes reveals insights on evolution and lignocellulose degradation potential.

Lyophyllum decastes, also known as Luronggu in China, is a culinary edible and medicinal mushroom that was widely cultivated in China in recent years. In the present study, the complete high-quality genome of two mating compatible L. decastes strain was sequenced. The L. decastes LRG-d1-1 genome consists of 47.7 Mb in 15 contigs with a contig N90 of 2.08 Mb and 14,499 predicted gene models. Phylogenetic analysis revealed that L. decastes exhibits a close evolutionary relationship to the Termitomyces and Hypsizygus genus and was diverged from H. marmoreus ~ 45.53 Mya ago. Mating A loci of L. decastes compose of five and four HD genes in two monokaryotic strains, respectively. Mating B loci compose of five STE genes in both two monokaryotic strains. To accelerate the cross-breeding process, we designed four pairs of specific primers and successfully detected both mating types in L. decastes. As a wood-rotting mushroom, a total of 541 genes accounting for 577 CAZymes were identified in the genome of L. decastes. Proteomic analysis revealed that 1,071 proteins including 182 CAZymes and 258 secreted enzymes were identified from four groups (PDB, PDB + bran, PDB + cotton hull, and PDB + sawdust). Two laccases and a quinone reductase were strongly overproduced in lignin-rich cultures, and the laccases were among the top-3 secreted proteins, suggesting an important role in the synergistic decomposition of lignin. These results revealed the robustness of the lignocellulose degradation capacity of L. decastes. This is the first study to provide insights into the evolution and lignocellulose degradation of L. decastes.

Non‐Isothermal Kinetics of Phoenix Dactylifera L. Date Palm Seeds Pyrolysis Using Model Fitting and Iso‐Conversional Model Free Methods

AbstractIn this paper, Phoenix dactylifera L. date palm seeds (RDS) were first characterized from a physicochemical point of view, in particular the proximate and ultimate composition, XRD, and SEM–EDX analyses. Based on findings RDS contains 77.4 % of total carbohydrates, 12.8 % of lignin, and a higher heating value (HHV) of 15.88 MJ kg−1. Immuno‐labeling intensity (OD) of non‐cellulosic RDS fraction was also determined thanks to the ELISA technique after the dissolution of polysaccharides in ionic liquid showing the presence of mannans and xyloglucans and the absence of arabinans in date seeds, a significant amount of homogalacturonans were also detected. The thermal decomposition and kinetic of date palm seeds (RDS) using TGA‐DTG, and DSC measurements were then investigated. The RDS samples were heated in the temperature ranges 25–600 °C at 5, 10, 15, and 20 °C/min. The decomposition of hemicelluloses, cellulose, and lignin, active pyrolysis of RDS, was held in a range of temperature 160–450 °C. The kinetic parameters such as activation energy (Ea) and pre‐exponential factor (A) were determined for two degradation steps by using iso‐conversional model‐free methods. The Ea and pre‐exponential factor obtained by the Kissinger method are 212 kJ mol−1 and 7.8×1019 min−1 for the first decomposition interval (I1) and 172 kJ mol−1 and 5.96×1013 min−1 for the second decomposition interval I2. The same average parameters calculated by model‐free methods are 126–156 kJ mol−1 and 180–213 kJ mol−1 and 3.36×1014 and 7.07×1017 min−1 respectively for the first and second intervals of thermal decomposition. Indicating that activation energy decreases in the final stages of the process and that the energy required for hemicelluloses degradation is lower than that of cellulose. The most probable reaction functions have been determined for these two stages, by Coats‐Redfern (CR) and Criado methods, leading to considerably improved calculation performance over the entire conversion range. The pyrolysis reaction models of RDS are described by reaction, second order F2 for cellulose and hemicelluloses. With the Arrhenius parameters obtained from the fitting model of CR, we attempt to reconstruct the temperature‐dependent mass conversion curves and have resulted in generally acceptable results. Based on the Arrhenius parameter values, obtained by the Kissinger equation, the changes in entropy, enthalpy, Gibbs free energy, and lifetime predictions have been estimated for the thermal degradation processes of RDS.

Elucidating the composition of organic matter in water-repellent forest soils using analytical pyrolysis combined with gas chromatography–mass spectrometry (Py-GC–MS)

Soil water repellency (SWR) is an inability of soil to spontaneously absorb water. It affects the spatial distribution of soil moisture, may cause formation of preferential flow, increase surface runoff and the risk of water erosion, or affect nutrient availability for crops. Although there is a general agreement among published data that SWR is caused by hydrophobic components of soil organic matter (SOM), more comprehensive information is needed. Additionally, the link between SWR occurrence and SOM genesis has not been studied sufficiently. In this work, we analyzed SOM in water-repellent soils by pyrolysis combined with gas chromatography and mass spectrometry (Py-GC–MS). The samples were taken from two forest ecosystems in Slovakia: relatively dry pine–oak forest, located in the Záhorská nížina lowland (Záhorie), and spruce forest in the High Tatras with a colder and more humid climate. The results showed that the composition of SOM at both sites is dominated by partially decomposed residues of plant biomass. Whereas most compounds detected in the Záhorie samples were identified as pyrolysis products of lignin, the pyrolysates of the High Tatras soils originated mainly from polysaccharide-like substances. Although lauric (12:0), myristic (14:0) and palmitic (16:0) fatty acids were detected in pyrograms of water-repellent samples, the results suggest that the residues of lignin decomposition may contribute to SWR as well. Pyrolysates such as methylguaiacol, vinylguaiacol, dimethylphenol, or the methyl ester of vanillic acid are examples of less polar lignin-like moieties. Py-GC–MS data, as well as other soil properties, suggest that SWR at both sites is associated with the accumulation of certain SOM components in the topsoil. Acidic pH, higher C/N ratio and coarse soil texture prevent organic carbon stabilization in the studied soils. As a result, SOM is in great part composed of accumulated particulate residues with lignin-like origin and lipidic coatings, which contribute to SWR development during drier conditions.

Improved Light Hydrocarbon, Furans, and BTEX Production from the Catalytic Assisted Pyrolysis of Agave salmiana Bagasse over Silica Mesoporous Catalysts

The pyrolysis of the biomass Agave salmiana bagasse (10 K/min, ambient to 700 °C) was investigated in the absence and presence of Aerosil and MCM-41 catalysts. MCM-41 was synthetized using a typical hydrothermal method and characterized with XRD, SAXS, SEM, TEM, and nitrogen physisorption to confirm the presence of unidimensional 3.4 nm diameter pores. Pyrolysis products were monitored online with mass spectrometry (MS), analyzing the production of 29 different compounds, clustered in several groups, namely, olefins (ethene, 2-butene, 1,3-butadiene), oxygenated compounds (methanol, 2-methylbutanol, acetic acid), furan derivatives (furan, furfural, 2-methylfurane), and aromatic compounds (BTEX). Complete decomposition of the cellulose and hemicellulose content of the biomass was observed at temperatures below 400 °C. Lignin decomposition was completed by 550 °C. Catalyst-assisted pyrolysis showed reduced acetic acid and methanol formation with Aerosil and MCM-41. The use of Aerosil does not affect the overall production of olefins, yet increases benzene yield, while reducing the production of phenol, furan, and furan derivatives. With MCM-41, there is increased production of olefins, furan, furan derivatives, cyclohexanone and BTEX, yet phenol production is decreased. At temperatures below 400 °C, the product formation pattern is comparable to non-catalytic pyrolysis.

Kinetic and thermodynamic analysis of biomass catalytic pyrolysis with nascent biochar in a two-stage reactor

The interaction between nascent biochar and volatiles is critical and complex during the biomass thermochemical conversion processes. Despite various experiments showing a link between pyrolysis products and biochar catalysts, it is difficult to interpret the detailed mechanistic for the interplay between kinetic and thermal effects. To improve the understanding of the effect of nascent biochar catalyst on the pyrolysis of biomass, both kinetic and thermodynamic analysis was carried out in this work. Several catalytic processes were designed to analyze the catalytic reactivity combined with the online characterization of TG-MS and TG-FTIR. The catalytic pyrolysis kinetics analysis revealed that the particle size exhibited limited influence on the pyrolysis activation energy and product evolution. However, the nascent biochar could effectively decrease the pyrolytic activated energy of corn cob and facilitate the decomposition of lignin. Furthermore, the biochar promoted the conversion from CO2 to CO and the production of H2. In addition, the nascent biochar effectively improved the purity of the pyrolysis product and reduced the selectivity of acid, alcohol and ester. In-situ and ex-situ catalysis achieved high selectivity of phenolic products, whose selectivity reached 46.71% and 55.96%, respectively. Hybrid feeding catalysis attained significant productions of ethers, achieving the selectivity of 48.88%.

Pyrolysis of tea and coffee wastes: effect of physicochemical properties on kinetic and thermodynamic characteristics

Physicochemical properties, kinetic pyrolysis and thermodynamic study of spent green tea, pure spent coffee grounds, spent coffee grounds blended with 50% torrefied barley and coffee husk were experimentally investigated using thermogravimetric analysis under an inert atmosphere to evaluate their thermochemical application. Five isoconversional methods were applied to determine effective activation energy (Ea) of the pyrolysis processes. All methods showed good agreement by determining fluctuating Ea values (150–500 kJ mol−1). Complex Ea profiles with conversion were divided into four stages corresponding to thermal degradation of main biomass constituents (extractives, hemicellulose, cellulose and lignin), indicating that extractives decomposition was the least demanding reaction while lignin decomposition was the most demanding. The kinetic process was verified by reconstruction according to the Friedman parameters. The thermodynamic parameters were evaluated to determine the energy demand and efficiency throughout the process. The values obtained for physicochemical properties such as volatile matter (> 68%) and higher heating value (> 17 MJ kg−1), average Ea (223–319 kJ mol−1) and significant energy efficiency implied that these types of biomass waste have significant reactivity and consequently the highest potential for the production of bioenergy and a range of high-value chemicals and materials.

Characterization of Ash from Sugar Palm [Arenga Pinnata (Wrumb) Merr.] Fiber for Industrial Application

ABSTRACT Sugar palm (Arenga Pinnata) fiber is abundant in Malaysia which necessitates its utilization as a source of agricultural waste for industrial development. This paper aims at characterizing the sugar palm fiber to explore its silica content as a potential renewable material. The sugar palm fiber was carbonized, and the ash obtained was characterized via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS) and field emission scanning electron microscope (FESESM). The presence of amorphous silica (SiO2) with an average particle size of 41.25 nm was revealed by X-ray diffraction. Fourier transform infrared spectroscopy indicated the presence of functional groups such as silane and siloxane groups, and thermogravimetric analysis and differential scanning calorimetry identified the main degradation stages of the sugar palm fiber ash, and the decomposition of hemicellulose, lignin, cellulose, and carbonate to other oxides. The energy dispersive spectroscopy of the sugar palm fiber ash confirmed silica to be of the highest amount than other elements. Sugar palm fiber ash has been found as a possible silica substitute and a prospective industrial resource.

Supercritical Hydrothermal Reactions for Material Synthesis

Abstract Since the early 1990s, Adschiri and his colleagues have performed research on the use of supercritical water in diverse applications, including heavy oil reforming, waste polymer decomposition and chemical raw materials recovery, cellulose hydrolysis and sugar recovery, lignin decomposition and chemical raw materials recovery, and nanoparticle synthesis. Regarding inorganic materials synthesis, they invented supercritical hydrothermal synthesis for the continuous flow synthesis of metal oxide nanoparticles, which has already found worldwide industrial applications. They proposed a two-fluid mixing flow system where an aqueous metal salt solution is mixed with supercritical water to heat the solution to the supercritical state within a very short time, that is not attainable by conventional reactor systems. Organic-inorganic hybrid nanoparticles synthesis was demonstrated in the supercritical state, realizing homogeneous phase formation of organic molecules at high loadings. By optimizing the reaction conditions, small facet-controlled nanoparticles with narrow particle size distribution can be obtained. Organic modification of nanoparticles is shown to be effective for fabricating highly concentrated nanohybrid polymers or nano inks. Furthermore, these synthesized facet-controlled nanoparticles show high catalytic activities. Indeed, it is demonstrated that steam reforming of heavy oils or biomass wastes (black liquor) can occur in water even at low temperatures.

ASSESSMENT OF THE EFFECT OF BIOCHAR ON THE PROCESS OF THERMOLISIS OF BIOMASS OF PLANTS GROWN ON RECLAIMED LANDS

Samples of soil contaminated with heavy metals for pot experiments with annual crops (maize, sweet and sudan sorghum) were taken near the mines "Pavlogradska" and "Blagodatna" in the coal-mining region of Western Donbass. The basis of the reclaimed areas was an 8-10 m thick mine rock (MR) dump, covered with different layers of black soil or red-brown clay by creating two types of soil artificial profiles with the addition of 30 cm of black soil (30 cm of BS +MR) and 50 cm red-brown clay (50 cm RBC + MR). Experimental soil samples were treated with 3.0% (w/w) biochar. The purpose of the study was to study the effect of the addition of biochar on the process of thermal destruction of the biomass of maize, sweet and sudan sorghum, grown on different substrates - components of artificial reclaimed profiles (upper layers of chernozem mass and red-brown clay). The process of thermolysis of biomass components of three agricultural crops was studied by the method of thermogravimetric analysis. Thermal destruction of the biomass of the three studied plant species occurred in two stages: evaporation of water and volatile compounds (stage 1) and decomposition of the main components: hemicellulose, cellulose and lignin (stage 2). The first stage took place in the temperature range of 50-180°С. The process was slow, the maximum speed did not exceed 5-8%/min, the extreme point was observed at a temperature of 100-110°C. Loss of body weight is insignificant, 4.5–7.5%. The second stage is divided into two phases: the decomposition of holocellulose with the beginning of lignin decomposition (phase 1) and the cessation of lignin decomposition, and the formation of non-combustible residue (phase 2). Destruction of holocellulose occurred in the temperature range of 190-390°С. Due to the large amount of hemicellulose in the biomass of the studied plants, its decomposition was shifted to the region of higher temperatures. Therefore, the degradation ranges of hemicellulose and cellulose overlapped, and only one extreme point was observed in the DTG curves. The process proceeded at high speeds with the peak of destruction in the temperature range of 280-310°C. Weight loss was also the most significant and was between 50 and 55%. Decomposition of lignin occurred rather slowly, with one insignificant peak in the temperature range of 420-440°C. A weight loss of 26-30% has been established. At the first stage, the process proceeded mainly with heat absorption; the reactions of the second stage were exothermic with noticeable thermal effects in the zones of cellulose and lignin decomposition. Differences in thermal characteristics of sugar sorghum biomass grown on different substrates and with the addition of biochar were determined in the process of thermolysis. Degradation of holocellulose occurred more slowly in biomass collected from a vessel with red-brown clay, in contrast to lignin, which decomposed faster than in the experiment where the substrate was a loose layer of chernozem. The share of non-combustible residues was almost 2 times smaller. A slight increase in the rate of the cellulose decomposition reaction (1,2 times) and a significant increase in the rate of the lignin destruction reaction (5 times) was observed. In the treatment with biochar, a more complete combustion of biomass was observed. The rate of cellulose decomposition in the experiment with red-brown clay became somewhat higher, although the decomposition of lignin occurred more slowly. The share of non-combustible residues increased by 1,8 times. Thermal destruction of Sudan grass biomass on both substrates occurred in a similar manner. The addition of biochar did not reveal significant deviations in the thermal behavior of biomass grown on chernozem, in contrast to the experiment with red-brown clay, where the addition of biochar contributed to a significant reduction in the duration of thermolysis. The first stage of thermolysis of corn biomass was somewhat shorter in the experiment with a bulk layer of chernozem compared to red-brown clay and was accompanied by a lower mass loss. The same trend was observed in the decomposition of holocellulose. At the same time, the destruction of lignin in the version with chernozem lasted longer, the extremum point was shifted to the region of higher temperatures, the speed of the process was almost twice as low as in the version with clay, and the proportion of non-combustible residue was 1,7. times higher. More complete combustion of corn biomass was also observed in the version with biochar.

Research on the optimum carbonization process of walnut shell based on dynamic analysis.

Walnut shell is characterized by high yield, high fixed carbon content, and low ash content. In this paper, the thermodynamic parameters for walnut shell during the carbonization process is investigated, and its carbonization and mechanism are discussed. Then, the optimal carbonization process of walnut shell is proposed. Results demonstrated that the comprehensive characteristic index of pyrolysis first increases and then decreases with the increase of heating rate and reaches the peak at about 10 °C min-1. Note that the carbonization reaction intensifies at this heating rate. The carbonization process of walnut shell is a complex reaction involving multiple steps. It decomposes hemicellulose, cellulose, and lignin in stages, and the activation energy of this process gradually increases. The simulation and experimental analyses showed that the optimal process presents a heating time of 14.8 min, final temperature of 324.7 °C, holding time of 55.5 min, particle size of material of about 2 mm, and optimum carbonization rate of 69.4%.

Co-circularity of spent coffee grounds and polyethylene via co-pyrolysis: Characteristics, kinetics, and products

Spent coffee grounds (CG) and polyethylene (PE) are the two typical types of major solid wastes. Their co-pyrolysis may be leveraged to reduce their waste streams and pollution and valorize energy and by-products. In this study, their co-pyrolysis performances, interaction effects, kinetics, and products were characterized in response to the varying temperature and blend ratio. The co-pyrolysis exhibited the two main stages of (1) the degradation of CG (180–380 °C) and (2) the depolymerization of PE and the decomposition of lignin (380–550 °C). The pyrolysis performance rose from 1.34×10−4%3·min−2·°C−3 with the mono-pyrolysis of CG to 26.32×10−4%3·min−2·°C−3 with the co-pyrolysis of 10 % CG and 90 % PE. The co-pyrolysis of 70 % CG and 30 % PE (CP73) achieved a lower activation energy than did the mono-pyrolysis of the two fuels. The products of the CG pyrolysis included a large number of alcohols, ethers, ketones, esters, and other oxygen-containing compounds, with a proportion as high as 65.01 %. The products of CP73 at 550 °C resulted in the yields of hydrocarbons and alcohols up to 93.61 %, beneficial to the further utilization of the co-pyrolytic products. Not only did the co-pyrolysis valorize its products, but also it enhanced their co-circularity. Artificial neural network-based joint optimization showed CP73 in the range of 517–1000 °C as the best combination of the conditions. The study provides new insights into the co-pyrolytic disposal of spent coffee grounds and polyethylene so as to improve the waste stream reduction and the valorization of energy and products.

A method for addressing compensation effect in determining kinetics of biomass pyrolysis

Compensation effect is an unsolved issue when determining pyrolysis kinetics of biomass using inverse modelling and optimization algorithms, implying no unique solution can be obtained. To address this problem, a new method coupling Gauss multi-peak fitting method, Kissinger method, a numerical model, and Shuffled Complex Evolution (SCE) optimization algorithm is proposed to extract kinetics from microscale thermogravimetric analysis (TGA) experiments and avoid attainment of unreasonable good-fit solutions. TGA tests of beech wood at nitrogen atmosphere were conducted at three heating rates. Gauss multi-peak fitting method was employed to separate the overlapped peaks in TGA curves and identify the contribution of each elemental component reaction. The kinetics of individual reactions were estimated by Kissinger method to provide an initial solution for SCE optimization. Then, narrow initial search ranges were determined to further refine the kinetics by SCE. By compiling previous data in literature and our optimization results, it was found compensation effect exists for individual basic components, hemicellulose, cellulose and lignin, following a linear correlation between lnA andEa, and among multiple components. Pyrolysis of hemicellulose can be modelled by either first-order or high-order reactions, while cellulose pyrolysis is more likely a first-order reaction. Nevertheless, the long tail in DTG curves associated with decomposition of lignin can only be captured by a high-order reaction. Although the Kissinger solution of lignin cannot be used in selecting an appropriate search range for SCE optimization, the narrow search ranges of the remaining kinetic parameters can ensure the accuracy and convergency efficiency of optimization.

Metagenomics analysis of the effects of Agaricus bisporus mycelia on microbial diversity and CAZymes in compost.

Agaricus bisporus growth alters the lignocellulosic composition and structure of compost. However, it is difficult to differentiate the enzyme activities of A. bisporus mycelia from the wider microbial community owing to the complication of completely speareting the mycelia from compost cultures. Macrogenomics analysis was employed in this study to examine the fermentation substrate of A. bisporus before and after mycelial growth, and the molecular mechanism of substrate utilization by A. bisporus mycelia was elucidated from the perspective of microbial communities and CAZymes in the substrate. The results showed that the relative abundance of A. bisporus mycelia increased by 77.57-fold after mycelial colonization, the laccase content was significantly increased and the lignin content was significantly decreased. Analysis of the CAZymes showed that AA10 family was extremely differentiated. Laccase-producing strains associated with AA10 family were mostly bacteria belonging to Thermobifida and Thermostaphylospora, suggesting that these bacteria may play a synergistic role in lignin decomposition along with A. bisporus mycelia. These findings provide preliminary evidence for the molecular mechanism of compost utilization by A. bisporus mycelia and offer a reference for the development and utilization of strains related to lignocellulose degradation.

Taxonomic and functional dynamics of the soil microbiome from a tropical dry forest in kraft lignin-amended microcosms

The Caatinga, a Brazilian dry tropical forest that sheds its leaves seasonally, harbors diverse lignocellulose-degrading microbes as a valuable source of lignin-modifying enzymes useful for the chemical and biofuel industry. Nonetheless, the detailed process of lignin decomposition in soils is still poorly understood due to most studies focusing on the biodegradation of non-ligninolytic components of plant biomass (i.e., cellulose, hemicellulose, and oligosaccharides). Hence, the microbial dynamic was investigated in kraft lignin (KL) amended soil microcosms incubated at 45 °C for 9, 18, and 27 days. The changes in the GC-MS profile indicated rapid and complete biodegradation of lignin-derived compounds (i.e., phenol, guaiacol, paracyclophane, eugenol, benzene, ethisterone, and methadone N-oxide) by the microbial ligninolytic systems. Metabarcoding analyses showed that species richness (Chao 1 index from 14313,6 ± 338 to 7230,4 ± 1056) and diversity (H′ index from 7,9 ± 0,05 to 5,6 ± 0,6) decreased in response to KL addition. However, the bacterial diversity was stabilized from the 18th to the 27th day, shaping a soil bacterial community dominated by members of the Proteobacteria (Bordetella and Roseomonas), Firmicutes (Bacillus, Pullulanibacillus, Lysinibacillus, Cohnela, and Ornithinibacilus), and Actinobacteria (Isoptericola, Saccharomonospora, and Beutenbergia) phyla, some of which have not yet been reported as able to degrade lignin. Although the KL addition has promoted the extinction of microbial taxa, the co-occurrence networks reveal high modularity values (0.92) of the microbial structure in the 18th and 27th days of KL-amended soil microcosms, indicating metabolic plasticity even with the ecological disturbance. Some individual taxa clustering into more distinct modules might be explained by the emergence of new ecological niches resulting from the heterogeneous features of KL. Metagenome-based evidence suggests that key bacterial (Bordetella and Streptomyces), and fungal (Aspergillus) members may play synergistic ecophysiological roles in decomposing lignin-derived compounds by carrying the most genes encoding lignin-modifying enzymes belonging to the auxiliary activity (AA) family. The great increase of Aspergillus-affiliated genes of the AA9 family (log ratio of 1.46), which includes the copper-dependent lytic polysaccharide monooxygenases (LPMOs), suggests a key role in lignin-derived compounds degradation. Overall, the insights gathered herein reveal the microbial dynamics of a tropical dry forest soil in kraft lignin-amended microcosms and open perspectives for a rational exploration of potentially novel enzymes and microbial candidates for biotechnological applications.

Co-pyrolysis of oil palm trunk and polypropylene: Pyrolysis oil composition and formation mechanism

Pyrolysis oil can be used as a precursor to synthesize value-added biochemicals. Co-pyrolysis of two or more feedstocks generally improves the selectivity and yield of the target compounds. In this work, oil palm trunk (OPT) was subjected to single-feed pyrolysis and co-pyrolysis with polypropylene (PP) from 500 to 700 °C. The highest pyrolysis oil yield of 26.33 wt.% was obtained from OPT at 700 °C, which mainly contributed by the lignin decomposition in OPT. Phenolics (51.77–57.78%) and oxygenates (36.31–46.99%) were the major compounds detected in the OPT-derived pyrolysis oil. The addition of PP enhanced the formation of hydrocarbons (5.19–10.22%) and decreased the contents of phenolics (34.01–41.85%) in the co-pyrolysis oil. In the case of co-pyrolysis, the intermolecular reactions between PP and OPT-derived radicals led to the formation of ketones and alcohols, which contributed to the increase of oxygenates content. The highest oil yield of 16.17 wt.% was obtained at 600 °C from co-pyrolysis, the oil of which contained mainly phenolic compounds, oxygenated compounds (i.e., ketones and furans), and hydrocarbons. These findings highlighted the potential of oil derived from the pyrolysis of OPT (single feed) and co-pyrolysis of OPT and PP (binary feed) for the production of value-added chemicals.

Thermal degradation and kinetic studies of redwood (Pinus sylvestris L.)

AbstractIn this scientific paper, thermochemical conversion of redwood (RW) was studied. Using the thermogravimetric analysis' technique (TGA), the thermal behavior of RW samples was examined at four heating rates ranging from 5 to 20 K min−1 in inert atmosphere between 300 and 900 K. Two main objectives have been set for this study; the first one was the determination of the kinetic decomposition parameters of RW (Pinus sylvestris L.), and the second one was the study of the variation of characteristic parameters from the TG-DTG curves of the main RW's components, such as; cellulose, hemicellulose and lignin. The kinetic analysis was performed using three isoconversional methods (Vyazovkin (VYA), Friedman (FR) and Flynn-Wall-Ozawa (FWO)), Avrami theory method and the Integral master-plots (Z(x)/Z(0.5)) method to estimate activation energy (Ea), reaction order (n), pre-exponential factor (A) and model kinetic (f(x)) for the thermal decomposition of cellulose, hemicellulose and lignin components.The DTG and TG curves showed that three stages identify the thermal decomposition of RW, the first stage corresponds to the decomposition of hemicellulose and the second stage corresponds to the cellulose, while the third stage corresponds to the lignin's decomposition. For the range of conversion degree (x) investigated (0.1 ≤ x ≤ 0.7), the mean values of apparent activation energies for RW biomass were 127.60–130.65 KJ mol−1, 173.74–176.48 KJ mol−1 and 197.21–200.36 KJ mol−1 for hemicellulose, cellulose and lignin, respectively. Through varied temperatures from 550 to 600 K for hemicellulose, from 600 to 650 K for cellulose and from 750 to 800 K for lignin, the corresponding mean values of reaction order (n) were 0.200 for hemicellulose, 0.209 for cellulose and 0.047 for lignin. The pre-exponential factor's average values for three components of RW ranges from 0.08 × 1012 s−1 to 2.5 × 1012 s−1 (Ahemicellulose = 1.09 × 1012 s−1), 0.10 × 1014 s−1 to 0.28 × 1014 s−1 (Acellulose = 0.17 × 1014 s−1) and 3.07 × 1016 s−1 to 3.69 × 1016 s−1 (Alignin = 3.33 × 1016 s−1), respectively. The experimental data of RW had overlapped the D4, D2 and F3 in the conversion degree of 10–30%, 30–55% and 55–70% for the three components, respectively.

Thermal oxidative aging mechanism of lignin modified bitumen

Lignin is the most abundant renewable resource in nature, which can be applied to not only improve resource utilization but also improve bitumen road performance. In this study, the evolution of lignin during thermal-oxidative aging of bitumen was investigated by dynamic shear rheology test (DSR), thermogravimetric test (TG) and Fourier transform infrared spectroscopy (FTIR). The thermo-oxidative aging mechanism of lignin modified bitumen was analyzed. The results show that lignin-modified bitumen had better aging resistance than the virgin bitumen. Meanwhile, the changes of functional group indices at 1460 cm−1, 1512 cm−1, and 1600 cm−1 in the infrared spectra proved that the thermal-oxidative aging mechanism was the decomposition of lignin itself under the action of thermal oxygen, which inhibited the aging process of bitumen.

Catalytic hydrolysis of corncob for production of furfural and cellulose-rich solids: Product characterization and analysis

Experiments were carried out to investigate cellulose and furfural from catalytic hydrolysis of corncob. This process improved the comprehensive utilization of hemicellulose and cellulose in biomass resources. Influence of factors (temperature, reaction time, concentration of catalysts, liquid to solid ratio (LSR)) on hydrothermal characteristics, furfural yield, properties and retention of cellulose were investigated through orthogonal and parameter tests. Acetic acid (6 wt%) and FeCl3 (40 mM) achieved the highest furfural yield (47.60%) and relatively high cellulose retention ratio (71.84%) at 180 °C, 45 min, and 3 mL/g of LSR. While AlCl3 and citric acid obtained low furfural yield and the lowest cellulose retention ratio (8.38%). Furfural was dominant in distillated organics (GC-MS areas ≥97.9%), by contrast furfural, 5-hydroxymethyfurfural and vanillin were main organics in residual liquors. The peak of furfural yield switched to shorter reaction time as temperature increased. Combination of AlCl3 with acetic acid and citric acid accelerated cellulose degradation. NaCl inhibited furfural yield and promoted lignin decomposition. Higher temperature and greater concentration of FeCl3 contributed to reduced crystallinity of cellulose during hydrothermal treatment.

Nutrient controls on carbohydrate and lignin decomposition in beech litter

Nutrient pollution has increased plant litter nutrient concentrations in many ecosystems, which may profoundly impact litter decomposition and change the chemical composition of litter inputs to soils. Here, we report on a mesocosm experiment to study how variations in the nitrogen (N) and phosphorus (P) concentrations in Fagus sylvatica (European beech) litter from four sites differing in bedrock, atmospheric deposition, and climate affect lignin and carbohydrate loss rates and residual litter chemistry. We show with pyrolysis GC/MS and elemental analysis that nutrient concentrations had a strong influence on changes in litter chemistry during early decomposition (0–181 days), when greater lignin loss rates were associated with low P concentrations, whereas carbohydrate and bulk C loss were associated with high N concentrations. Nutrient concentrations, in contrast, did not influence changes in litter chemistry in the later decomposition stage (181–475 days), where the decomposition rates of lignin, carbohydrates, and bulk C all increased with litter N concentration and no differences in decomposition rates between major compound classes were detected. Our data indicate that these differences were related to the transition from increasing to constant or declining microbial biomass, and an associated decrease in microbial dependence on the mobilization of nutrients from the insoluble litter fraction.

Properties, Physiological Functions and Involvement of Basidiomycetous Alcohol Oxidase in Wood Degradation.

Extensive research efforts have been devoted to describing yeast alcohol oxidase (AO) and its promoter region, which is vastly applied in studies of heterologous gene expression. However, little is known about basidiomycetous AO and its physiological role in wood degradation. This review describes several alcohol oxidases from both white and brown rot fungi, highlighting their physicochemical and kinetic properties. Moreover, the review presents a detailed analysis of available AO-encoding gene promoter regions in basidiomycetous fungi with a discussion of the manipulations of culture conditions in relation to the modification of alcohol oxidase gene expression and changes in enzyme production. The analysis of reactions catalyzed by lignin-modifying enzymes (LME) and certain lignin auxiliary enzymes (LDA) elucidated the possible involvement of alcohol oxidase in the degradation of derivatives of this polymer. Combined data on lignin degradation pathways suggest that basidiomycetous AO is important in secondary reactions during lignin decomposition by wood degrading fungi. With numerous alcoholic substrates, the enzyme is probably engaged in a variety of catalytic reactions leading to the detoxification of compounds produced in lignin degradation processes and their utilization as a carbon source by fungal mycelium.