Unveiling the fundamental chemistry of lignin under ionic liquid (IL) pretreatment will facilitate the understanding of biomass recalcitrance involved in pretreatment processes. To examine in greater ...detail the chemical transformations of lignin under different IL pretreatment conditions without competing reactions from plant polysaccharides, the IL pretreatment of the isolated poplar alkaline lignin (hardwood lignin) under varying IL pretreatment conditions (i.e., 110-170 degree C, 1-16 hours) was performed in an appropriate manner. The structural transformations of the lignin have been investigated by elemental analysis, 2D-HSQC spectra, quantitative super(13)C-NMR spectra, super(31)P NMR, and GPC analysis. Results revealed that a decrease of aliphatic OH and an increase in phenolic hydroxyl groups occurred in lignin as the pretreatment proceeded. The increased phenolic OH was mainly as a result of cleavage of beta -O-4' linkages, while the reduced aliphatic OH is probably attributed to the dehydration reaction. The cleavage of beta -O-4' linkages, degradation of beta - beta ' and beta -5' linkages obviously happened at high temperatures and resulted in the decrease of molecular weights. In addition, IL pretreatment selectively degraded the G-type lignin fractions and the condensation reaction took place more easily at S units than G units. Moreover, the demethoxylation preferentially occurred in G units, especially at higher temperatures. It is believed that investigating the fundamental chemistry of lignin during IL pretreatments would be beneficial to optimize and control the pretreatment process.
Lignin is the most abundant aromatic polymer in nature. However, the utilization of lignin is very limited and almost exclusively used for combustion to generate heat and power. Considering the ...abundance, low cost, and environmentally benign nature of lignin, as well as its unique molecular structure, the use of lignin-derived materials to construct high-performance rechargeable batteries to meet the massive demand for rechargeable batteries has attracted worldwide attention as an emerging research frontier. This review systematically summarizes the recent advances in lignin-derived materials and their applications in rechargeable batteries. The basic physical and chemical properties of lignin are first introduced. Subsequently, recent advances in lignin-derived electrode materials, including porous carbon and lignin carbon fibers, as well as lignin-derived binders, separators, and electrolytes, are discussed. Finally, perspectives on the further development of advanced lignin-derived materials for rechargeable batteries are presented.
This review summarizes the current advances on the application of lignin-based materials in rechargeable batteries regarding electrode materials, binders, separators, and electrolytes, respectively.
Microwave pyrolysis (MP) has emerged as a promising technique to valorize agricultural wastes (AW) into biofuels, comprising biochar, bio-oil, and syngas. To fill the research gap, we review the ...state-of-the-art MP conversion of AW into value-added biofuels, including the influence of feedstock composition, new reactor designs, operating conditions, catalytic applications, and reaction mechanisms. The techno-economic and environmental impacts are discussed together with key implications for future development. Microwave valorization of AW to biofuels represents an economically viable cum environmentally-benign approach by virtue of (i) high availability of AW, (ii) scalable process, (iii) great potentiality for continuous operation, and (iv) thermochemical process with positive energy ratio. For continuous MP, the microwave heating distribution, products yield, and reactor design have not yet fully explored due to the limited understanding on microwave propagation pattern, materials handling, and varying feedstock compositions. The utilization of AW as biofuels feedstock offers several environmental advantages in terms of improved biomass utilization, enhanced carbon sequestration, and lower sulphur emission. The toxicity of bio-oil can be reduced by adding metal oxide catalysts (CaO, CuO, MgO, and NiO) to lessen its content of polycyclic aromatic hydrocarbons. The process of continuous MP can be optimized by coupling shaftless auger and multiple magnetron to improve the quality of the biofuel, and uniformity of microwave heating. It is envisaged that continuous conversion of AW to biofuels is a sustainable, low carbon footprint, and alternative energy generation route, provided that the appropriate catalyst, effective condenser, and self-purging condition are chosen.
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•Review on applications, new designs of microwave pyrolysis of agricultural wastes.•Agricultural wastes show environmental advantages as a sustainable feedstock.•Microwave pyrolysis produce biochar, bio-oil, and syngas as value-added biofuels.•It is scalable, able to run in continuous operation with positive energy ratio.•A potential fast approach for sustainable low carbon footprint biofuel production.
In recent years, flexible electronics have developed rapidly in wearable and intelligent devices. There are still great challenges in the development of high-precision flexible strain sensors. Here, ...an ultra-precise strain sensor of solely biobased materials was realized by a surface graphitization strategy, which cleverly gives the biobased film excellent conductivity to ensure the original flexibility. The strain sensors have an ultra-precise response (gauge factor of 46.65 and linear fitting R 2 as high as 0.99903) and high tensile strength (1.2 MPa). The as-assembled strain sensors can not only accurately detect human body movement, but also be completely dissolved in water after use. The green, precise strain sensors have enabled application cases of human–computer interaction and the internet of things and have great development prospects in the field of intelligent applications. This will promote the development of biobased materials in the fields of flexible electronics and human–machine interaction in ultra-precise sensing.
Environmental issues and constantly diminishing petroleum resources are considerable barriers inhibiting modernization, and vast efforts have been exerted to address these problems. Carbon fibers ...(CFs) are carbon materials with high mechanical strength and functionality for applications in construction, electronics, transportation, and aviation. Currently, most CFs are produced from polyacrylonitrile, a petroleum-based, unsustainable, and non-renewable chemical of relatively high price. Interestingly, lignin is an inexpensive, highly accessible, and renewable resource. It has been utilized to fabricate lignin-based carbon fibers (LCFs), which have met rapid development during the past two decades. In this review, LCFs are generalized by focusing on their steps of manufacture. Resource types and corresponding pretreatments ensure the processability of spinning and thermal treatments. Fibers are formed
via
spinning methods, including melt-spinning, wet-spinning, dry-spinning, and electrospinning. The next step is the most significant process of stabilization, in which fibers are oxidized, crosslinked, and thermally stabilized for pyrolysis. Subsequent to carbonization and/or additional processes (activation and graphitization), LCFs are obtained. Each step can influence the terminal performance of LCFs, which is discussed in detail. Recently produced LCFs of sub-micron size, also known as lignin-based carbon nanofibers (LCNFs), are detailed. Furthermore, attributed to the excellent performance and low cost of LCFs and LCNFs, they have been applied in various fields, predominantly for electronic devices such as batteries and supercapacitors. Our review is concluded with opinions on the potential for further advancement of this promising material.
This review details recent progress in the conversion of technical lignins to multi-functional, high-value, and promising carbon fiber materials, and discusses their applications.
Biodegradable materials are increasingly imperative in modern society owing to their eco-friendly character, but their high cost and limited properties restrict their applications. In this study, ...lignin-based (30-50 wt%) biodegradable composites with superior performances were successfully prepared by incorporating lignin into the poly(butylene adipate-
co
-terephthalate) (PBAT) matrix. In order to improve the compatibility, lignin was efficiently modified by a green esterification reaction under microwave-assisted solvent-free conditions. Comprehensive characterization revealed that modified lignin had fewer inter-unit linkages, increased molecular weights, lower
T
g
and enhanced hydrophobicity. Moreover, the prepared modified lignin/PBAT composites reinforced with maleic anhydride (MAH) exhibited controllable improvements in mechanical properties and exhibited excellent UV-shielding properties, and their elongation at break, even with 40 wt% lignin, increased by 500% compared to that of unmodified counterparts. The ideal dispersion and compatibility of the modified lignin in the matrix facilitated the mechanical properties of composites, as revealed by morphological and thermal analysis. Importantly, molecular dynamics (MD) simulation unprecedentedly confirmed that the modification of lignin distinctly strengthened molecular interaction and compatibility of the matrices, enhancing the mechanical performance of the composites. This work presents a green and feasible route to produce cost-efficient biodegradable materials with controlled mechanical and UV-shielding properties for packaging application.
Biodegradable composite materials are increasingly imperative in modern society owing to their eco-friendly character, and further reducing costs and improving compatibility of composites will facilitate their applications.
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•Single-step combining steam/CO2 and microwave pyrolysis is used to produce biochar.•Steam/CO2 performed dual functions, acting as purging gas and activating agent.•Microwave CO2 ...activated biochar contains more micropores.•Microwave steam activated biochar contains more mesopores.•Activated biochar shows good adsorption efficiency on carcinogenic Congo Red dye.
We developed an innovative single-step pyrolysis approach that combines microwave heating and activation by CO2 or steam to transform orange peel waste (OPW) into microwave activated biochar (MAB). This involves carbonization and activation simultaneously under an inert environment. Using CO2 demonstrates dual functions in this approach, acting as purging gas to provide an inert environment for pyrolysis while activating highly porous MAB. This approach demonstrates rapid heating rate (15–120 °C/min), higher temperature (> 800 °C) and shorter process time (15 min) compared to conventional method using furnace (> 1 h). The MAB shows higher mass yield (31–44 wt %), high content of fixed carbon (58.6–61.2 wt %), Brunauer Emmett Teller (BET) surface area (158.5–305.1 m2/g), low ratio of H/C (0.3) and O/C (0.2). Activation with CO2 produces more micropores than using steam that generates more mesopores. Steam-activated MAB records a higher adsorption efficiency (136 mg/g) compared to CO2 activation (91 mg/g), achieving 89–93 % removal of Congo Red dye. The microwave pyrolysis coupled with steam or CO2 activation thereby represents a promising approach to transform fruit-peel waste to microwave-activated biochar that remove hazardous dye.
The application of non woody biomass materials in the manufacture of wood‐based panels has been confirmed as an efficient carbon sequestration approach. In this study, reed straw was recommended to ...produce reed‐based particleboards (RPs). Sieving and hydrothermal pre‐treatments were conducted on the inner layer reed particles to reduce the adverse influence of the waxy layer on the mechanical strength of RPs. The thickness swelling rate was merely 1.04% (2 h), and the internal bonding strength could reach up to 0.88 MPa, which met the ISO requirements for heavy‐duty load bearing in dry conditions (P‐HLB REG). More importantly, this study constructed the plate forming process that retains the natural morphological characteristics of reed to the maximum extent. Generally, the mechanical strength of RPs was markedly higher than mostly straw‐based and even wood‐based panels. The static bending strength of RPs could reach 35.6 MPa after sieving pre‐treatment. In addition, according to the LCA, the net carbon flux could reach −1227.55 kg CO2 eq. when producing 1 m3 RPs. The obtained RPs could be utilized as wood substitutes to produce furniture and building materials with promising environmental and economic benefits.
This study promoted a viable strategy exploiting reed straw to make reed‐based particleboards with ultra‐high mechanical strength via simple pre‐treatments (sieving and hydrothermal) of inner layer reed straw particles.
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•A green and scalable waste-free biorefinery was proposed.•Fractionation and functionalization were simultaneously achieved during pretreatment.•In-situ esterification enhanced the ...water contact angle of LCNF film to 103.3°.•Enhanced amphiphilicity facilitated lignin self-assembly into LNPs (30–75 nm).•Waste DES was successfully upgraded into N-doped CDs.
The introduction of nanotechnology into conventional biorefinery will facilitate complete valorization of lignocellulosic biomass. In this work, a microwave-assisted deep eutectic solvent (DES) pretreatment was developed for one-pot fractionation of bamboo biomass into three scalable fractions (cellulose-rich residue, lignin and recovered DES), which were then respectively upgraded to three value-added bio-based nanomaterials, namely lignin-containing cellulose nanofibrils (LCNFs), lignin nanoparticles (LNPs) and carbon quantum dots (CDs). After the mild and rapid DES pretreatment (130 °C, 20 min), 51.0% cellulose-rich residue was recovered accompanied by 90.6% delignification ratio. The cellulose-rich residues were mechanically fibrillated into LCNFs with a width of 5–20 nm. In-situ esterification of carboxylic acid groups from DES with cellulose hydroxyl groups improved the hydrophobicity of LCNFs. The LCNFs film prepared exhibited excellent hydrophobic (water contact angle of 103.3°). In-situ esterification, condensation and cleavage reactions of lignin during DES fractionation enhanced its amphiphilicity and facilitated lignin self-assembly into LNPs with diameters of 30–75 nm. Furthermore, using the recovered DES as carbon precursors, CDs were successfully prepared by a typical hydrothermal method, which provides a new approach for the disposal of waste DES. In short, the proposed waste-free biorefinery scheme realizes the complete valorization of bamboo biomass into bio-based multifunctional nanomaterials, which can be further applied in various downstream fields.
