Lignin is an abundant biopolymer with a high carbon content and high aromaticity. Despite its potential as a raw material for the fuel and chemical industries, lignin remains the most poorly utilised ...of the lignocellulosic biopolymers. Effective valorisation of lignin requires careful fine‐tuning of multiple “upstream” (i.e., lignin bioengineering, lignin isolation and “early‐stage catalytic conversion of lignin”) and “downstream” (i.e., lignin depolymerisation and upgrading) process stages, demanding input and understanding from a broad array of scientific disciplines. This review provides a “beginning‐to‐end” analysis of the recent advances reported in lignin valorisation. Particular emphasis is placed on the improved understanding of lignin's biosynthesis and structure, differences in structure and chemical bonding between native and technical lignins, emerging catalytic valorisation strategies, and the relationships between lignin structure and catalyst performance.
Seeing the wood for the trees: Lignin is an abundant biopolymer with a high carbon content and high aromaticity. A critical analysis of “upstream” and “downstream” elements of lignin valorisation is given, including bioengineering, biorefining, and catalysis.
To realize direct power generation from biofuels in natural organisms, we demonstrate a needle-type biofuel cell (BFC) using enzyme/mediator/carbon nanotube (CNT) composite fibers with the structure ...Osmium-based polymer/CNT/glucose oxidase/Os-based polymer/CNT. The composite fibers performed a high current density (10 mA/cm2) in 5 mM artificial blood glucose. Owing to their hydrophilicity, they also provided sufficient ionic conductivity between the needle-type anode and the gas-diffusion cathode. When the tip of the anodic needle was inserted into natural specimens of grape, kiwifruit, and apple, the assembled BFC generated powers of 55, 44, and 33 μW from glucose, respectively. In addition, the power generated from the blood glucose in mouse heart was 16.3 μW at 0.29 V. The lifetime of the BFC was improved by coating an anti-fouling polymer 2-methacryloyloxyethyl phosphorylcholine (MPC) on the anodic electrode, and sealing the cathodic hydrogel chamber with medical tape to minimize the water evaporation without compromising the oxygen permeability.
•Needle –type biofuel cell (BFC) was developed with flexible enzyme/mediator/CNT fibers for direct power generation from glucose in natural organisms.•The bioanode for glucose oxidation and oxygen-diffusion biocathode fibers are prepared through modification with glucose oxidase and bilirubin oxidase, respectively, on CNT decorated carbon fibers.•Both biofibers are assembled to the needle BFC and generate a power (55 μW, 44 μW, 33 μW, 8.5 μW, and 16.3 μW) from glucose in grape, kiwifruit, apple, mouse abdominal cavity, and its heart, respectively.
The shortage of fossil fuels is actually a major economic issue in the context of increasing energy demand. Renewable energies are thus gaining in importance. For instance, microalgae-based fuels are ...viewed as an alternative. Microalgae are microscopic unicellular plants, which typically grow in marine and freshwater environments. They are fast growing, have high photosynthetic efficiency, and have relatively small land requirement and water consumption in comparison with conventional land crops biofuels. Nonetheless, selling biofuels is still limited by high cost. Here, we review biofuel production from microalgae, including cultivation, harvesting, drying, extraction and conversion of microalgal lipids. Cost issues may be solved by upstream and downstream measures: (1) upstream measures, in which highly productive strains are obtained by strain selection, genetic engineering and metabolic engineering, and (2) downstream measures, in which high biofuels yields are obtained by enhancing the cellular lipid content and by advanced conversion of microalgal biomass to biofuels. Maximum biomass and high biofuels production can be achieved by two-stage culture strategies, which is a win–win approach because it solves the conflicts between cell growth and biomass accumulation.
The enzymatic biofuel cell (EBFC) has been considered as a promising implantable energy generator because it can extract energy from a living body without any harm to the host. However, an ...unprotected enzyme will be destabilized and even eventually be deactivated in human blood. Thus, the performance of implantable EBFC has received barely any improvement. It is therefore a breakthrough in realizing a superior efficient EBFC that can work stably in human blood which relies in protecting the enzyme to defend it from the attack of biological molecules in human blood. Herein, we innovatively created a single-walled carbon nanotube (SWCNT) and cascaded enzyme-glucose oxidase (GOx)/horseradish peroxidase (HRP) coembedded hydrophilic MAF-7 biocatalyst (SWCNT-MAF-7-GOx/HRP). The SWCNT-MAF-7-GOx/HRP is highly stable in electrocatalytic activity even when it is exposed to high temperature and some molecular inhibitors. In addition, we were pleasantly surprised to find that the electrocatalytic activity of GOx/HRP in hydrophilic SWCNT-MAF-7 far surpasses that of the GOx/HRP in hydrophobic SWCNT-ZIF-8. In human whole blood, the SWCNT-MAF-7-GOx/HRP catalytic EBFC exhibits an eightfold increase in power density (119 μW cm–2 vs 14 μW cm–2) and 13-fold increase in stability in comparison with the EBFC based on an unprotected enzyme. In this study, the application of metal–organic framework-based encapsulation techniques in the field of biofuel cells is successfully realized, breaking a new path for creating implantable bioelectrical-generating devices.
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•A magnetic cellulose-derived solid acid (MCC-SO3H) was prepared and characterized.•MCC-SO3H was active in the conversion of fructose-based carbohydrates to biofuel EMF.•MCC-SO3H was ...easily separated by an external magnet and displayed a good reusability.•Integrated use of biobased feedstock, catalyst and solvent is a sustainable strategy.
A series of carbonaceous solid acid catalysts were prepared by facile carbonization and sulfonation of biorenewable feedstocks (i.e., glucose, sucrose, starch and cellulose), and employed for directly converting carbohydrates in ethanol medium to synthesize 5-ethoxymethylfurfural (EMF). The carbonization temperature of cellulose and starch (500 °C) was required to be higher than that of glucose and sucrose (400 °C) to realize high –SO3H density and EMF yield. Based on rich exploitability of cellulose and good activity of its derived carbonaceous catalyst, magnetic cellulose-derived carbonaceous solid acid (MCC-SO3H) was subsequently synthesized, which possessed a porous structure with BET surface area of 35.34 m2 g–1, high –SO3H density (1.28 mmol g–1) and sufficient magnetism for separation (1.99 emu g–1). By optimizing the process variables, a maximum EMF yield of 63.2% could be achieved from fructose at 120 °C, and ethyl levulinate formation was favored at elevated temperature. The MCC-SO3H catalyst could be readily separated from the reaction mixture by an external magnet with recovery rate of 92.6% after six successive runs, and reused repeatedly with little deactivation. Besides, this catalyst was efficient for the one-pot transformation of fructose-based polysaccharides into EMF, affording yields of 51.3% and 32.5% from inulin and sucrose, respectively. With glucose as the substrate, instead ethyl glucoside with a high yield of 86.5% was obtained.
The catalytic conversion of (bio)ethanol into butanol is an attractive route to upgrade the modest fuel characteristics of this widely available bioderived substrate into a molecule that has ...properties much closer to conventional gasoline. The Guerbet reaction, known for more than 100 years, provides an ideal mechanism for this transformation. However, despite the apparently simple nature of this reaction for ethanol, it provides formidable challenges, especially in terms of achieving high selectivity. There have been advances in both heterogeneous and homogeneous catalysis in this regard, and this Perspective focuses on the very recent reports of homogeneous catalysts that describe encouraging results in terms of achieving high selectivity, mechanistic understanding, and widening scope.
Characterization of crude glycerol is very important to its value-added conversion. In this study, the physical and chemical properties of five biodiesel-derived crude glycerol samples were ...determined. Three methods, including iodometric–periodic acid method, high performance liquid chromatography (HPLC), and gas chromatography (GC), were shown to be suitable for the determination of glycerol content in crude glycerol. The compositional analysis of crude glycerol was successfully achieved by crude glycerol fractionation and characterization of the obtained fractions (aqueous and organic) using titrimetric, HPLC, and GC analyses. The aqueous fraction consisted mainly of glycerol, methanol, and water, while the organic fraction contained fatty acid methyl esters (FAMEs), free fatty acids (FFAs), and glycerides. Despite the wide variations in the proportion of their components, all raw crude glycerol samples were shown to contain glycerol, soap, methanol, FAMEs, water, glycerides, FFAs, and ash.
Highlights ► The supply of external nitrogen to microalgae cultivation is energy intensive. ► Recycling the nitrogen contained in the non-triacylglyceride portion of microalgae may circumvent the ...negative energy impacts associated with external nitrogen supply. ► Decisions on how to reuse nitrogen must be made within the context of the overall energy balance, sustainability, and commercialization potential of the microalgae biorefinery.
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