Because of the increase in the transmission voltage levels, the demand for insulation reliability of power transformers has increasingly become critical. Cellulose insulating paper is the main insulating component of power transformers. To improve the insulation level of ultrahigh voltage transformers and reduce their weight and size, reducing the dielectric constant of oil-immersed cellulose insulating paper is highly desired. Cellulose is used to produce power-transformer insulating papers owing to its excellent electrical properties, renewability, biodegradability and abundance. The dielectric constant of a cellulose insulating paper can be effectively reduced by chemical or physical modification. This study presents an overview of the foreign and domestic research status of the use of modification technology to reduce the dielectric constant of cellulose insulating papers. All the mentioned methods are analyzed in this study. Finally, some recommendations for future modified cellulose insulating paper research and applications are proposed. This paper can provide a reference for further research on low dielectric constant cellulose insulating paper in the future.
Powering the future, while maintaining strong socioeconomic growth and a cleaner environment, is going to be one of the biggest challenges faced by mankind nowadays. Thus, there is a transition from the use of fossil fuels to renewable energy sources. Cellulose, the main component of paper, represents a unique type of bio-based building blocks featuring exciting properties: low-cost, hierarchical fibrous structures, hydrophilicity, biocompatible, mechanical flexibility, and renewability, which make it perfect for use in paper-based sustainable energy storage devices. This review focuses on lithium-ion battery application of celluloses with cellulose at different scales, i.e., cellulose microfibers, and nanocellulose, and highlights the new trends in the field. Recent advances and approaches to construct high mass loading paper electrodes toward high energy density batteries are evaluated and the limitations of paper-based cathodes are discussed. This will stimulate the use of natural resources and thereby the development of renewable electric energy systems based on sustainable technologies with low environmental impacts and carbon footprints.
Electrodes that combine energy storage with mechanical and photothermal performance are necessary for efficient development and use of flexible energy storage and conversion devices. In this study, the flexible, ultrathin, and multifunctional polypyrrole/cellulose nanofiber composite films were fabricated via a one-step “soak and polymerization” method. The dense sandwich structure and strong interfacial interaction endowed polypyrrole/cellulose nanofiber composite films with excellent flexibility, outstanding mechanical strength, and desired toughness. Interestingly, the polypyrrole/cellulose nanofiber composite film electrodes with quaternary amine functionalized cellulose nanofiber had the highest specific mass capacitance (392.90 F∙g–1) and specific areal capacitance (3.32 F∙cm–2) than the electrodes with unmodified and carboxyl functionalized cellulose nanofibers. Further, the polypyrrole/cellulose nanofiber composite films with sandwich structure had excellent photothermal conversion properties. This study demonstrated a feasible and versatile method for preparing of multifunctional composite films, having promising applications in various energy storage fields.
Phase change materials are potential candidates for the application of latent heat storage. Herein, we fabricated porous capsules as shape-stable materials from cellulose-based polyelectrolyte complex, which were first prepared using cellulose 6-(N-pyridinium)hexanoyl ester as the cationic polyelectrolyte and carboxymethyl cellulose as the anionic polyelectrolyte to encapsulate polyethylene glycol by the vacuum impregnation method. Furthermore, the multi-walled carbon nanotube or graphene oxide, which were separately composited into the polyelectrolytes complex capsules to enhance thermal conductivity and light-to-thermal conversion efficiency. These capsules owned a typical core–shell structure, with an extremely high polyethylene glycol loading up to 34.33 g∙g‒1. After loading of polyethylene glycol, the resulted cellulose-based composite phase change materials exhibited high thermal energy storage ability with the latent heat up to 142.2 J∙g‒1, which was 98.5% of pure polyethylene glycol. Further results showed that the composite phase change materials demonstrated good form-stable property and thermal stability. Moreover, studies involving light-to-thermal conversion determined that composite phase change materials exhibited outstanding light-to-thermal conversion performance. Considering their exceptional comprehensive features, innovative composite phase change materials generated from cellulose presented a highly interesting choice for thermal management and renewable thermal energy storage.
This research is a follow-up to our recent discovery of a facile strategy for directly converting lignin powder into carbon foam. In this work, we report that the thermal pretreatment parameters in air can remarkably influence the formation and properties of the derived carbon foam. Thermal pretreatment parameters (heating rate, temperature, and residence time) were systematically investigated and a conversion mechanism into carbon foam was proposed. During the thermal pretreatment, relatively low temperatures, low heating rates, and short residence time hindered the formation of smooth and well-connected structures in the carbon foam. The overall product yields were similar regardless of the thermal pretreatment conditions. The densities of the different carbon foams ranged 0.27–0.83 g∙cm−3. The carbon foams with the highest compressive strengths (> 10 MPa) were KLPC280-2-5, KLPC300-0-5, and KLPC300-2-2.5. KLPC280-2-5 exhibited a high iodine sorption value (182 mg∙g−1). KLPC300-2-5 exhibited a specific capacitance of 158 F∙g−1 at a current density of 0.05 A∙g−1. The maximum evaporation rates in the solar vapor generation experiments were 1.05 and 1.38 kg∙m−2∙h−1 under 100 and 150 mW∙cm−2 irradiation, respectively. The good performances are attributed to the robust, porous, and continuous structure.
Lignocellulosic biomass such as plants and agricultural waste are ideal to tackle the current energy crisis and energy-related environmental issues. Carbon-rich lignin is abundant in lignocellulosic biomass, whose high-value transformation and utilization has been the most urgent problem to be solved. Herein, we propose a method for the preparation of porous carbon from lignin employing an H3PO4-assisted hydrothermal method. We characterize the as-prepared lignin-derived porous carbon and investigate its potential for energy storage. After assisted hydrothermal treatment followed by carbonization at 800 °C, the lignin-derived porous carbon displays a high specific capacitance (223.6 F·g–1 at 0.1 A·g–1) and excellent cycling ability with good capacitance retention. In this present study, the resultant lignin-derived porous carbon was used as the electrode of a supercapacitor, illustrating yet another potential high-value use for lignin, namely as a candidate for the sustainable fabrication of main supercapacitor components.
Inspired by the importance of the phenolic group to the electron transporting property of hole transport materials, phenolic hydroxyl groups were introduced in lignosulfonate (LS) via the alkyl chain bridging method to prepare phenolated-lignosulfonate (PLS). The results showed that the phenolic group was boosted from 0.81 mmol∙g–1 of LS to 1.19 mmol∙g–1 of PLS. The electrochemical property results showed two oxidation peaks in the cyclic voltammogram (CV) curve of PLS, and the oxidation potential of the PLS-modified electrode decreased by 0.5 eV compared with that of LS. This result indicates that PLS is more easily oxidized than LS. Based on the excellent electron transporting property of PLS, PLS was applied as a dopant in poly(3,4-ethylenedioxythiophene) (PEDOT, called PEDOT:PLSs). PLS showed excellent dispersion properties for PEDOT. Moreover, the transmittance measurement results showed that the transmittance of PEDOT:PLSs exceeded 85% in the range of 300–800 nm. The CV results showed that the energy levels of PEDOT:PLSs could be flexibly adjusted by PLS amounts. The results indicate that the phenolic hydroxyl group of lignin can be easily boosted by the alkyl chain bridging method, and phenolated lignin-based polymers may have promising potential as dopants of PEDOT to produce hole transporting materials for different organic photovoltaic devices.
The aromatic properties of lignin make it a promising source of valuable chemicals and fuels. Developing efficient and stable catalysts to effectively convert lignin into high-value chemicals is challenging. In this work, MnFe2O4 spinel catalysts with oxygen-rich vacancies and porous distribution were synthesized by a simple solvothermal process and used to catalyze the depolymerization of lignin in an isopropanol solvent system. The specific surface area was 110.5 m2∙g–1, which substantially increased the active sites for lignin depolymerization compared to Fe3O4. The conversion of lignin reached 94%, and the selectivity of alkylphenols exceeded 90% after 5 h at 250 °C. Underpinned by characterizations, products, and density functional theory analysis, the results showed that the catalytic performance of MnFe2O4 was attributed to the composition of Mn and Fe with strong Mn–O–Fe synergy. In addition, the cycling experiments and characterization showed that the depolymerized lignin on MnFe2O4 has excellent cycling stability. Thus, our work provides valuable insights into the mechanism of lignin catalytic depolymerization and paves the way for the industrial-scale application of this process.
Derivatization has great potential for the high-value utilization of cellulose by enhancing its processability and functionality. However, due to the low reactivity of natural cellulose, it remains challenging to rapidly prepare cellulose derivatives with high degrees of substitution. The “cavitation effect” of ultrasound can reduce the particle size and crystalline index of cellulose, which provides a possible method for preparing cellulose derivatives. Herein, a feasible method was proposed for efficiently converting regenerated cellulose to cellulose oleate with the assistance of ultrasonic treatment. By adjusting the reaction conditions including ultrasonic intensity, feeding ratios of oleic acid, reaction time, and reaction solvent, a series of cellulose oleates with degrees of substitution ranging from 0.37 to 1.71 were synthesized. Additionally, the effects of different reaction conditions on the chemical structures, crystalline structures, and thermal behaviors were investigated thoroughly. Cellulose oleates with degrees of substitution exceeding 1.23 exhibited amorphous structures and thermoplasticity with glass transition temperatures at 159.8 to 172.6 °C. This study presented a sustainable and practicable method for effectively derivatizing cellulose.
This research undertook a case study of the life-cycle assessment and techno-economic analysis of the slow pyrolysis of Eucommia stem for the production of wood vinegar and activated carbon. The results showed that the production of one ton of wood vinegar via the slow pyrolysis of Eucommia stem show comparatively low global warming potential (2.37 × 102 kg CO2 eq), primary energy demand (3.16 × 103 MJ), acidification potential (2.19 kg SO2 eq), antimony depletion potential (3.86 × 10–4 kg antimony eq), and ozone depletion potential (7.46 × 10–6 kg CFC-11 eq) and was more environmentally friendly than the production of dilute acetic acid (12 wt %) via petrochemical routes. Meanwhile, the total capital investment, total product cost, and cash flowsheet were provided in the techno-economic analysis. Then, the net present value, internal rate of return, and dynamic payback period of the production process were evaluated. The findings indicated that while this production process is cost-effective, it might not be economically attractive or could generate investment risks. An increase in the added value of the wood vinegar and the activated carbon could remarkably improve the economic feasibility of this production process.
Biomass-derived porous carbons have been considered as the most potential candidate for effective CO2 adsorbent thanks to being widely-available precursor and having highly porous structure and stable chemical/physical features. However, the biomass-derived porous carbons still suffer from the poor optimization process in terms of the synthesis conditions. Herein, we have successfully fabricated coconut shell-derived porous carbon by a simple one-step synthesis process. The as-prepared carbon exhibits advanced textual activity together with well-designed micropore morphology and possesses oxygen-containing functional groups (reached 18.81 wt %) within the carbon matrix. Depending on the different activating temperatures (from 700 to 800 °C) and KOH/biomass mass ratios (from 0.3 to 1), the 750 °C and 0.5 mass ratio were found to be enabling the highest CO2 capture performance. The optimal adsorbent was achieved a high CO2 uptake capacity of 5.92 and 4.15 mmol·g−1 at 0 and 25 °C (1 bar), respectively. More importantly, as-prepared carbon adsorbent exhibited moderate isosteric heat of adsorption and high CO2/N2 selectivity. The results were revealed not only the textural feature but also the surface functional groups critically determine the CO2 capture performance, indicating coconut shell-derived porous carbon has a considerable potential as a solid-state adsorbent for the CO2 capture.
Riboflavin sodium phosphate has been confirmed as a promising biomass product derived from natural plants. In this paper, a novel method of dyeing and multifunctional modification of silk fabric by impregnation with riboflavin sodium phosphate was proposed, such that protein silk fabric can be endowed with bright yellow color and multi-functionality. The results of this paper confirmed that the pH and concentration of riboflavin sodium phosphate solution are critical factors for dyeing and multifunctional modification. Attractively, the photochromic performance was one of the most distinctive features of the modified silk fabric, and the dyed silk fabric turned into fluorescent green from original yellow under 365 nm ultraviolet lamp. Furthermore, the modified silk fabric exhibited good antibacterial properties with a high inhibition rate of 92% for Escherichia coli. Besides, the flame retardancy of silk fabric was significantly improved after modification. The damaged length of modified silk fabric with 40% owf riboflavin sodium phosphate was lower than 10.4 cm and passed the B1 classification. As revealed by the result of this paper, riboflavin sodium phosphate is sufficiently effective in serving as an eco-friendly multifunctional agent for strengthening the add-value of silk textiles.
