Tingting You

Interconnected Hierarchical Porous Carbon from Lignin-Derived Byproducts of Bioethanol Production for Ultra-High Performance Supercapacitors

The advent of bioethanol production has generated abundant lignin-derived byproducts which contain proteins and polysaccharides. These byproducts are inapplicable for direct material applications. In this study, lignin-derived byproducts were used for the first time as carbon precursors to construct an interconnected hierarchical porous nitrogen-doped carbon (HPNC) via hydrothermal treatment and activation. The obtained HPNC exhibited favorable features for supercapacitor applications, such as hierarchical bowl-like pore structures, a large specific surface area of 2218 m(2) g(-1), a high electronic conductivity of 4.8 S cm(-1), and a nitrogen doping content of 3.4%. HPNC-based supercapacitors in a 6 M KOH aqueous electrolyte exhibited high-rate performance with a high specific capacitance of 312 F g(-1) at 1 A g(-1) and 81% retention at 80 A g(-1) as well as an excellent cyclic life of 98% initial capacitance after 20 000 cycles at 10 A g(-1). Moreover, HPNC-based supercapacitors in the ionic liquid electrolyte of EMI-BF4 displayed an enhanced energy density of 44.7 Wh kg(-1) (remaining 74% of max value) at an ultrahigh power density of 73.1 kW kg(-1). The proposed strategy may facilitate lignin utilization and lead to a green bioethanol production process.

Progressive deconstruction of Arundo donax Linn. to fermentable sugars by acid catalyzed ionic liquid pretreatment.

Acid enhanced ionic liquid (IL) 1-n-butyl-3-methylimidazolium chloride ([C4 mim]Cl) pretreatment has shown great potential for boosting the yield of sugars from biomass cost-effectively and environmental-friendly. Pretreatment with shorter processing time will promote the commercial viability. In this work, pretreatment of reduced Amberlyst catalysis time of 34 min was demonstrated to be the most effective among time-varying pretreatments, evidenced by partial removal of hemicellulose and cellulose crystal transformation of Arundo donax Linn. A higher fermentable sugar concentration of 10.42 g/L (2% substrate) was obtained after 72 h of saccharification than the others. Total processing time to reach 92% glucose yield was cut down to approximately 26 h. Progressive deconstruction of crop cell wall was occurred with increased catalysis time by gradual releasing of H3O(+) of Amberlyst. However, vast lignin re-deposited polymers on fibers could hinder further enzymatic hydrolysis. These discoveries provide new insights into a more economic pretreatment for bioethanol production.

Microwave-assisted efficient depolymerization of alkaline lignin in methanol/formic acid media

Microwave-assisted degradation of alkaline lignin in methanol/formic acid media was investigated, concerning the effect of formic acid (FA) amount, reaction temperature, and reaction time on lignin depolymerization. The highest bio-oil yield of 72.0 wt% including 6.7 wt% monomers was achieved at 160 °C and a FA-to-lignin mass ratio of 4 after a reaction time of 30 min. Among the monomers, the yield of 2,3-dihydrobenzofuran was the highest (3.00 wt%), followed by p-coumaric acid (1.59 wt%). Formic acid acted mainly through acid-catalyzed cleavage of the linkages in lignin. Oligomers in bio-oil were mainly composed of dimers (molecular weight: 253-378) and trimers (molecular weight: 379-510) according to the Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) analysis. A possible mechanism about microwave-assisted depolymerization of lignin in methanol/formic acid media was proposed. This study will provide an efficient approach for lignin depolymerization.

Chemical composition, properties, and antimicrobial activity of the water-soluble pigments from Castanea mollissima shells.

Agricultural residues Castanea mollissima shells represent a promising resource for natural pigments for the food industry. This study provides a comprehensive and systematic evaluation of water-soluble pigments (CSP) from C. mollissima shells, which were obtained by 50% ethanol with microwave-assisted extraction. Spectroscopic techniques (UV, FT-IR, (13)C NMR), elemental analysis, and chromatographic techniques (HPAEC, GPC) revealed that the main components in the CSP were flavonoids procyanidin B3 (condensed tannin), quercetin-3-O-glycoside, and steroidal sapogenins. As a consequence, CSP was water-soluble and presented significant DPPH scavenge capacity (EC50 value was 0.057 mg/mL). Specially, CSP gave excellent antibacterial activity, and even better than 5% aqueous phenol in some case. Moreover, CSP was practically nontoxic and exhibited good stability with temperature, natural light, and metal ions. These outstanding properties will enlarge the application of CSP for natural food additives production.

Exploring the mechanism of high degree of delignification inhibits cellulose conversion efficiency

This study explored the mechanism that high degree of delignification (DD) inhibits enzymatic hydrolysis. Sample with DD of 86.22% achieved the highest cellulose conversion of 68.26%, and the cell wall exhibited defibrillation of macrofibrils and erosion of microfibrils during enzymatic hydrolysis. Cracks between microfibrils are formed within the cell wall, getting the largest specific surface area, which greatly enhanced cellulose conversion. However, high DD of 96.58% resulted in dramatic reduction of cellulose conversion to 56.60% which was evidenced to be the synergistic effect of internal cell wall collapse and microfibrils reaggregation. These ultrastructural changes dominated upon this condition and induced a more compact surface structure which significantly hinders the accessibility of cellulase. The CrI value increased after delignification but changed little with the increased DD, suggesting limited influence of DD on crystalline structure. The results indicate that certain amount of lignin retained may be essential to enhance cellulose conversion.

Reconstruction of lignin and hemicelluloses by aqueous ethanol anti‐solvents to improve the ionic liquid‐acid pretreatment performance of Arundo donax Linn

Ionic liquid (IL)‐acid pretreatment is known to not only enhance the enzymatic hydrolysis efficiency of lignocellulose but also to generate deposits on the surface of fiber by conventional water regeneration, which retard the increment. In this study, ethanol aqueous solution regeneration was developed as a new method to change the substrates characteristics for IL‐acid pretreatment and their effects on the enzymatic hydrolysis were evaluated. Following the IL‐acid reaction, the biomass slurry was subjected to ethanol aqueous solution at various concentration. Results indicated that anti‐solvent choice significantly influenced the reconstruction of both hemicelluloses and lignin as a result of the competition between water and ethanol. The partial removal of hemicelluloses and suitable lignin re‐localization contributed to a more porous structure. Consequently, the cellulose digestibility of aqueous ethanol regenerated samples was dramatically enhanced to ∼100% and approximately 11‐ and 2‐fold higher than that of untreated and conventional water regenerated pretreated samples, respectively. A giant leap in the initial rate of enzymatic hydrolysis was also detected in 50% ethanol aqueous solution regenerated samples and only about 10 hr was needed to convert 80% of cellulose to glucose due to the appearance of cellulose II hydrate‐like and more porous structure.