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Some agroforestry residues such as orange and olive tree pruning have been extensively evaluated for their valorization due to its high carbohydrates content. However, lignin-enriched residues generated during carbohydrates valorization are normally incinerated to produce energy. In order to find alternative high added-value applications for these lignins, a depth characterization of them is required. In this study, lignins isolated from the black liquors produced during soda/anthraquinone (soda/AQ) pulping of orange and olive tree pruning residues were analyzed by analytical standard methods and Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (solid state 13C NMR and 2D NMR) and size exclusion chromatography (SEC). Thermal analysis (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)) and antioxidant capacity (Trolox equivalent antioxidant capacity) were also evaluated. Both lignins showed a high OH phenolic content as consequence of a wide breakdown of β-aryl ether linkages. This extensive degradation yielded lignins with low molecular weights and polydispersity values. Moreover, both lignins exhibited an enrichment of syringyl units together with different native as well as soda/AQ lignin derived units. Based on these chemical properties, orange and olive lignins showed relatively high thermal stability and good antioxidant activities. These results make them potential additives to enhance the thermo-oxidation stability of synthetic polymers.

Milled wood lignin (MWL) was isolated from Dendrocalamus sinicus, an abundant bamboo variety in the earth, using Bjorkman method. Elucidation and quantification of the chemical structures for the isolated MWL have been facilitated by employing FT-IR and NMR techniques. The obtained results showed that the MWL consists of syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) units, indicating it as grass type (HGS) lignin. There is no significant change in structure (i.e. cleavage at α-O-4′ and β-O-4′ linkage) was observed. NMR techniques indicated that the isolated lignin was rich in β-O-4′ aryl ether substructures and syringyl (S) units. Furthermore, the sufficient understanding of the chemical structure of the lignin benefits their effective utilization towards the production of renewable biomass and biofuels.

The heterogeneous and recalcitrant structure of lignin hinders its practical application. Here, we describe how new approaches to lignin characterization can reveal structural details that could ultimately lead to its more efficient utilization. A suite of methods, which enabled mass balance closure, the evaluation of structural features, and an accurate molecular weight (MW) determination, were employed and revealed unexpected structural features of the five alkali lignin fractions obtained with preparative size-exclusion chromatography (SEC). A thermal carbon analysis (TCA) provided quantitative temperature profiles based on sequential carbon evolution, including the final oxidation of char. The TCA results, supported with thermal desorption/pyrolysis gas chromatography–mass spectrometry (TD-Py-GC-MS) and 31P NMR spectroscopy, revealed the unfolding of the lignin structure as a result of the SEC fractionation, due to the disruption of the interactions between the high- and low-MW components. The “unraveled” lignin revealed poorly accessible hydroxyl groups and showed an altered thermal behavior. The fractionated lignin produced significantly less char upon pyrolysis, 2 vs. 47%. It also featured a higher occurrence of low-MW thermal evolution products, particularly guaiacol carbonyls, and more than double the number of OH groups accessible for phosphitylation. These observations indicate pronounced alterations in the lignin intermolecular association following size-exclusion fractionation, which may be used for more efficient lignin processing in biorefineries.

Timber densification is a process that has been around since the early 1900s and is predominantly used to enhance the structural properties of timber. The process of densification provides the timber with a greater mechanical strength, hardness, abrasion resistance, and dimensional stability in comparison to its virgin counterparts. It alters the cellular structure of the timber through compression, chemical impregnation, or the combination of the two. This in turn closes the voids of the timber or fills the porosity of the cell wall structure, increasing the density of the timber and, therefore, changing its properties. Several processes are reported in literature which produce densified timber, considering the effect of various parameters, such as the compression ratio, and the temperature on the mechanical properties of the densified timber. This paper presents an overview of the current processes of timber densification and its corresponding effects. The material properties of densified timber, applications, and possible future directions are also explored, as the potential of this innovative material is still not fully realised.

The structure of cellulolytic enzyme lignin (CEL) prepared from three bamboo species (Neosinocalamus affinis, Bambusa lapidea, and Dendrocalamus brandisii) has been characterized by different analytical methods. The chemical composition analysis revealed a higher lignin content, up to 32.6% of B. lapidea as compared to that of N. affinis (20.7%) and D. brandisii (23.8%). The results indicated that bamboo lignin was a p-hydroxyphenyl-guaiacyl-syringyl (H-G-S) lignin associated with p-coumarates and ferulates. Advanced NMR analyses displayed that the isolated CELs were extensively acylated at the γ-carbon of the lignin side chain (with either acetate and/or p-coumarate groups). Moreover, a predominance of S over G lignin moieties was found in CELs of N. affinis and B. lapidea, with the lowest S/G ratio observed in D. brandisii lignin. Catalytic hydrogenolysis of lignin demonstrated that 4-propyl-substituted syringol/guaiacol and propanol guaiacol/syringol derived from β-O-4′ moieties, and methyl coumarate/ferulate derived from hydroxycinnamic units were identified as the six major monomeric products. We anticipate that the insights of this work could shed light on the sufficient understanding of lignin, which could open a new avenue to facilitate the efficient utilization of bamboo.

Solar desalination emerged as a promising and sustainable method for addressing the water shortage issue. Although wood can be converted to photothermal materials by surface coating and carbonization, many challenges such as the poor hydrophilicity, vulnerability to oil contamination and lipophilic micro-organisms of photothermal wood-based materials still remain. Moreover, it is difficult to form a stable chemical bond between the photothermal coating and the wood substrate, which hinders the improvement of corresponding solar evaporator. Therefore, we have prepared a wood-based solar desalination device (PPy-E-Wood) by in situ polymerization of pyrrole monomer on the pre-treated elastic wood. Successfully, efficient steam generation is achieved through the synergistic effect of the high photothermal conversion layer of PPy NPs, and the wood substrate with low thermal conductivity, micro/nano-pores and channels. The hydrophilicity and porous structure of PPy-E-Wood ensure a continuous water supply to its air–water interface, which give it a high solar conversion efficiency of 86% and an evaporation rate of 1.35 kg·m−2·h−1 under 1 kW·m−2. In addition, PPy-E-Wood has excellent structural stability, recoverability, electrical conductivity, and high salinity tolerance. Notably, the salt crystallized on its surface under ultra-high light (3 kW·m−2) can be dissolved by the natural alternation of day and night. Significantly, this wood-based photothermal material could easily realize its structural design and significantly improve its evaporation rate to 1.55 kg·m−2·h−1 or even 1.65 kg·m−2·h−1. Besides, PPy-E-Wood possesses not only the excellent superhydrophilicity and underwater superoleophobicity, but also an outstanding separation efficiency towards oil-in-water emulsions (~ 98%). We hope this work offer a new path to manufacturing and designing the wood-based photothermal materials for alleviating the global water and energy shortage.In this study, an elastic and shape-diversified photothermal matrix material with abundant internal cellulose network was prepared by removing part of lignin from raw wood, which acted as substrate and could be designed with various structures, and loading PPy on its top by in-situ polymerization of pyrrole for achieving photothermal conversion. Under the synergistic effect of superwetting substrate and photothermal top-coating, PPy-E-Wood realize the functions of seawater desalination and oil–water separation, providing a promising solution for water purification.

Background The efficient utilization of lignocellulosic biomass for biofuel production has received increasing attention. Previous studies have investigated the pretreatment process of biomass, but the detailed enzymatic hydrolysis process of pretreated biomass remains largely unclear. Thus, this study investigated the pretreatment efficiency of dilute alkali, acid, hydrogen peroxide and its ultimate effects on enzymatic hydrolysis. Furthermore, to better understand the enzymatic digestion process of alkali-pretreated sweet sorghum straw (SSS), multimodal microscopy techniques were used to visualize the enzymatic hydrolysis process. Result After pretreatment with alkali, an enzymatic hydrolysis efficiency of 86.44% was obtained, which increased by 99.54% compared to the untreated straw (43.23%). The FTIR, XRD and SEM characterization revealed a sequence of microstructural changes occurring in plant cell walls after pretreatment, including the destruction of lignin–polysaccharide interactions, the increase of porosity and crystallinity, and reduction of recalcitrance. During the course of hydrolysis, the cellulase dissolved the cell walls in the same manner and the digestion firstly occurred from the middle of cell walls and then toward the cell wall corners. The CLSM coupled with fluorescent labeling demonstrated that the sclerenchyma cells and vascular bundles in natural SSS were highly lignified, which caused the nonproductive bindings of cellulase on lignin. However, the efficient delignification significantly increased the accessibility and digestibility of cellulase to biomass, thereby improving the saccharification efficiency. Conclusion This work will be helpful in investigating the biomass pretreatment and its structural characterization. In addition, the visualization results of the enzymatic hydrolysis process of pretreated lignocellulose could be used for guidance to explore the lignocellulosic biomass processing and large-scale biofuel production.

Wood-derived carbon has a 3D porous framework composed of through channels along the growth direction, which is a suitable matrix for preparing electromagnetic wave (EMW) absorbing materials with low cost, light weight, and environmental friendliness. Herein, the carbonized wood decorated by short cone-like NiCo 2 O 4 (NiCo 2 O 4 @CW) with highly ordered straight-channel architecture was successfully manufactured through a facile calcination procedure. The horizontal arrangement of the through channels of NiCo 2 O 4 @CW (H-NiCo 2 O 4 @CW) exhibits a strong reflection loss value of -64.0 dB at 10.72 GHz with a thickness of 3.62 mm and a low filling ratio of 26 wt% (with the density of 0.98 g·cm -3 ), and the effective absorption bandwidth (EAB) is 8.08 GHz (9.92–18.0 GHz) at the thickness of 3.2 mm. The excellent microwave absorption (MA) property was ascribed to the ordered-channel structure with abundant interfaces and defects from NiCo 2 O 4 @CW, which could promote the interfacial polarization and dipole polarization. What is more, this advantageous structure increased the multiple reflections and scattering. Finite element analysis (FEA) simulation is carried out to detect the interaction between the prepared material and EMW when the ordered channels are arranged in different directions. This research provides a low-cost, sustainable, and environmentally friendly strategy for using carbonized wood to fabricate microwave absorbers with strong attenuation capabilities and light weight.

Business cost concern of solid adsorbents has motivated the production of porous activated carbons from waste biomass materials. In this work, three hierarchical porous activated carbons (HPAC) are obtained using hardwood alkali lignin (HPAC-H), sodium lignosulfonate (HPAC-L), and softwood alkali lignin (HPAC-S) as precursors and potassium hydroxide (KOH) as inorganic template and activation agent. their morphology and structure are characterized by Scanning electron microscopy (SEM), Nitrogen adsorption/desorption isotherms, X-ray diffraction spectroscopy (XRD), the Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS). Furthermore, the microscopic morphology of HPAC-H is rough surface with irregular pores and channels with uniform diameters; HPAC-L is hollow spheres of different sizes; and HPAC-S is solids particles with honeycomb pores. And they have a hierarchical porous structure with macro-meso-micropore. Moreover, HPAC-H exhibits the highest specific surface area (2852 m 2 ·g −1 ), the largest total pore volume (1.50 cm 3 ·g −1 ) and the highest oxygen content (10.61 at%) as compared to HAPC-L (2397 m 2 ·g −1 , 1.37 cm 3 ·g −1 , and 9.13 at%) and HAPC-S (2518 m 2 ·g −1 , 1.41 cm 3 ·g −1 , and 9.59 at%). In adsorption tests, the adsorption data of three activated carbons fits well with the Langmuir and Freundlich equations. The maximum methylene-blue (MB) adsorption capacity onto HPAC-H, HPAC-L, and HPAC-S calculated by Langmuir equation is 1671.66 mg·g −1 , 1182.84 mg·g −1 , and 1409.32 mg·g −1 , respectively. The excellent absorption capacity should be benefited from high surface area, the improved interconnected macro-meso-microporous framework and enriched surface functional groups. The obtained high-performance hierarchical porous activated carbons can afford a noteworthy potential for removing dye from wastewater.

Castor is an important non-edible oilseed crop used in the production of high-quality bio-oil. In this process, the leftover tissues rich in cellulose, hemicellulose and lignin are regarded as by-products and remain underutilized. Lignin is a crucial recalcitrance component, and its composition and structure strongly limit the high-value utilization of raw materials, but there is a lack of detailed studies relating to castor lignin chemistry. In this study, lignins were isolated from various parts of the castor plant, namely, stalk, root, leaf, petiole, seed endocarp and epicarp, using the dilute HCl/dioxane method, and the structural features of the as-obtained six lignins were investigated. The analyses indicated that endocarp lignin contained catechyl (C), guaiacyl (G) and syringyl (S) units, with a predominance of C unit [C/(G+S) = 6.9:1], in which the coexisted C-lignin and G/S-lignin could be disassembled completely. The isolated dioxane lignin (DL) from endocarp had a high abundance of benzodioxane linkages (85%) and a low level of β-β linkages (15%). The other lignins were enriched in G and S units with moderate amounts of β-O-4 and β-β linkages, being significantly different from endocarp lignin. Moreover, only p-coumarate (pCA) incorporated into the epicarp lignin was observed, with higher relative content, being rarely reported in previous studies. The catalytic depolymerization of isolated DL generated 1.4–35.6 wt% of aromatic monomers, among which DL from endocarp and epicarp have high yields and excellent selectivity. This work highlights the differences in lignins from various parts of the castor plant, providing a solid theory for the high-value utilization of the whole castor plant.