•Catalyst screening was done for HTL of biomass in hot-compressed water.•Bio-crude oil products were comprehensively characterized.•Composition of the oils highly depends on catalyst type.•The ...maximum oil yield of ∼40wt% was obtained with KOH catalyst.•HT & KOH catalysts promoted formation of phenol derivatives and aliphatic compounds.
Hydrothermal liquefaction of woody biomass (birchwood sawdust) with and without catalyst was investigated at 300°C for 30min. The activities of KOH, FeSO4·7H2O, K2CO3, MgO, synthetic hydrotalcite (HT), and ground colemanite (calcium borate mineral) as catalysts were compared. The alkaline catalysts (KOH, K2CO3 and colemanite) showed the best performance considering the oil yield and solid residue yield. The bio-crude oil yield with KOH was increased to around 40wt%, more than double the yield of the un-catalyzed operation (∼18wt%). It also reduced the solid residue yield from approx. 33 to 12wt%. Among all catalysts tested, the least active catalysts for bio-crude oil production are FeSO4 and MgO. The bio-crude oil products were comprehensively characterized using an elemental analyzer, GC–MS, FT-IR, GPC and TGA. Occurrence of phenol derivatives (mainly 2-methoxy-phenol) and aliphatic compounds increased significantly in presence of catalysts, especially the alkaline ones such as HT and KOH. The GPC results indicate that the oils produced in the presence of catalysts have very similar molecular weights and distribution, which are slightly greater than the oil produced in absence of any catalyst, suggesting that the presence of a catalyst promoted certain condensation/polymerization of the reaction intermediates during the HTL process. The TGA results show that all bio-crude oils are similar with respect to thermal stability, irrespective of the presence or type of catalyst.
•Acetic acid/formic acid/water mixture (3:6:1 v/v/v) proved to be the best solvent.•Cornstalk fractionation with HCl catalyst resulted in higher crude cellulose yield.•90°C and 180min residence time ...appeared to be optimal conditions.•53.0% yield of crude cellulose with 85.0% purity was obtained.•38.0% yield of crude lignin with 44.0% purity was obtained.
In this study, effects of fractionation solvents, catalysts, temperatures and residence time on yields, purity and chemical composition of the products were investigated at the solid/solvent ratio of 1:5 (g/g). It was revealed that mixture of acetic acid/formic acid/water at the ratio of 3:6:1 (v/v/v) resulted in crude cellulose and lignin products of relatively high purity. The use of HCl catalyst contributed to a high crude cellulose yield, while H2SO4 showed an adverse effect on cellulose yield. However, both of these acidic catalysts contributed to much lower hemicellulose contents in the resulted crude cellulose products compared with those obtained without a catalyst. Fractionation at 90°C for 180min in mixed solvents of acetic acid/formic acid/water (3:6:1, v/v/v) with or without catalyst produced crude cellulose with very low residual lignin contents (<4%).
Sludge is a semi-solid residue produced from wastewater treatment processes. It contains biodegradable and recalcitrant organic compounds, as well as pathogens, heavy metals, and other inorganic ...constituents. Sludge can also be considered a source of nutrients and energy, which could be recovered using economically viable approaches. In the present paper, several commonly used sludge treatment processes including land application, composting, landfilling, anaerobic digestion, and combustion are reviewed, along with their potentials for energy and product recovery. In addition, some innovative thermo-chemical techniques in pyrolysis, gasification, liquefaction, and wet oxidation are briefly introduced. Finally, a brief summary of selected published works on the life cycle assessment of a variety of sludge treatment and end-use scenarios is presented in order to better understand the overall energy balance and environmental burdens associated with each sludge treatment pathway. In all scenarios investigated, the reuse of bioenergy and by-products has been shown to be of crucial importance in enhancing the overall energy efficiency and reducing the carbon footprint.
Matrine is a traditional Chinese medicine and botanical pesticide with broad biological activities, including pharmacological and agricultural activities. In present work, two matrine derivatives ...have been successfully synthesized via introducing indole and cyclohexylamino to 13 position of matrine, respectively, with sophocarpine as starting material, and structurally characterized via infrared spectroscopy(IR), MS, 1 H NMR, 13 C NMR and X-ray crystal diffraction. The results of the in vitro biological activity tests showed that these two matrine derivatives exhibited even better activities against human cancer cells Hela229 and insect cell line Sf9 from Spodoptera frugiperda (J. E. Smith) than that of parent matrine, suggesting that the heterocyclic or cyclic group can dramatically increase the biological activity of matrine. It is worth to mention that 13-indole-matrine could possibly inhibit the growth of insect cells or human cancer cells by inducing cell apoptosis. The results of the present study provide useful information for further structural modifications of these compounds and for exploring new, potent anti-cancer agents and environment friendly pesticides.
This work aimed to degrade alkali lignin (AL) for the production of bio-phenolic compounds. Effective degradation of AL was achieved in 50/50 (v/v) water–ethanol at 200–450 °C under 5 MPa H2 with or ...without a catalyst. Hydrothermal treating AL at 300 °C for 2 h without a catalyst led to an 89% yield of degraded lignin (DL). The molecular weights of the lignin were significantly reduced from its original Mw and Mn of 60,000 and 10,000 g/mol to Mw and Mn of 1010 and 415 g/mol, respectively. Compared to the 50/50 (v/v) water–ethanol treatment, the pure ethanol treatment at 300 °C led to a lower yield of DL (<15%) with smaller molecular weights (Mw = 631 g/mol and Mn = 260 g/mol). Moreover, the DLs from the pure ethanol treatment were completely soluble in THF, in comparison, only ∼30% soluble in THF for DL from the 50/50 (v/v) water–ethanol treatment. While reaction time had negligible effects on the DL yields and properties, reaction temperature dramatically influenced the product yield and properties: 300–325 °C and 400 °C appeared to be the optimal temperature for the process in 50/50 (v/v) water–ethanol and pure ethanol, respectively. In both solvent-systems, generally the use of a catalyst did not significantly affect the yields of DL, but slightly reduced the molecular weights of the DLs and greatly increased the solubility of DLs in tetrahydrofuran (THF).
In this study, crude cellulose derived from cornstalk, after bleaching, was used as raw material for the synthesis of sodium carboxymethyl cellulose (CMC) by reacting with the cellulose with NaOH and ...chloroacetic acid at 75 °C for 1.5 h. Effects of alkali dosage, concentration of chloroacetic acid on the physical and chemical properties of the CMC products were investigated. It was revealed that the reactants alkali reagent/chloroacetic acid/cellulose at the molar ratio of 4.6:2.8:1and 4:2.5:1, or at the molar ratio of NaOH/ClCH2COOH ≈1.6–1.64, resulted in CMC products of relatively high water solubility. The viscosity-average molecular weight Mv of these two CMC products obtained at molar ratios of 4.0:2.5:1 and 4.6:2.8:1 is in the range of 1.94 × 104–2.48 × 104 g mol−1, and the average DS of the two products are 0.57 and 0.85, respectively. As the solute concentration is above 2 wt%, the viscosity of the CMC-water solution exhibits nonlinear (exponential) increasing with increasing the solute concentration (typical of non-Newton fluids).
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•Crude cellulose derived from cornstalk was used for the synthesis of CMC.•The best reactants molar ratio of NaOH/ClCH2COOH/cellulose found to be 4.6:2.8:1•At the best reactants molar ratio, the CMC product has a DS of 0.85•The CMC products have high water solubility, high viscosity & molecular weights.
•Thermal stability of lignin-based epoxy composites were investigated using TGA-FTIR.•Lignin-based epoxy composites are more effective fire retardants than a commercial epoxy resin.•Thermal ...decomposition kinetics were evaluated by KAS and FWO methods.•Activation energy of the decomposition process depended on the amount of lignin-epoxy resins.
Lignin-based epoxy resins derived from depolymerized Kraft/organosolv lignins were blended with a commercial bisphenol A (BPA)-type epoxy resin at various percentages to prepare bio-based epoxy composites. The thermal stability and thermal decomposition kinetics of lignin-based epoxy composites were investigated using thermogravimetric analysis coupled with Fourier transformation infrared spectroscopy (TGA-FTIR) and compared with the conventional BPA-based epoxy resin. The activation energy of the decomposition process of the cured lignin-based epoxy composites was calculated by Kissinger, Kissinger-Akahira-Sunoe (KAS), and Flynn-Wall-Ozawa (FWO) methods. The presence of lignin-based epoxy resin demonstrated a significant effect on the activation energy of the decomposition process in particular at the early and the final stages of decomposition. The increase in the percentage of lignin-based epoxy resins in the composites reduced the initial activation energy of the system. Carbon oxides, methane, carbonyl compounds, amines and aromatic compounds were identified as the principal components during the thermal decomposition of the bio-based epoxy composites.
•Co-liquefaction of spent coffee grounds and lignocellulosic feedstocks.•Liquefaction conditions: 250°C, feedstock combination ratio 1:1 and 5% NaOH as a catalyst.•In co-liquefaction of SCG and CS, ...the oil yield was increased by 20.9%.
Co-liquefaction of spent coffee grounds (SCG) with paper filter (PF), corn stalk (CS) and white pine bark (WPB) respectively, was examined in subcritical water for bio-crude oil production. The optimum reaction temperature was 250°C, and the mixing biomass ratio was 1:1. SCG and CS was identified to be the best feedstock combination with a significant positive synergetic effect in the co-liquefaction process with 5% NaOH as a catalyst. The yield of bio-crude oil was increased by 20.9% compared to the mass averaged yield from two feedstocks, and the oil quality was also improved in terms of viscosity and relative molecular mass. A negative effect presented in the co-liquefaction of SCG/WPB. The resulting bio-crude oils were characterized by elemental analyzer, GC–MS, GPC and viscometer, indicating that mixing feedstock in the co-liquefaction process also influenced the higher heating value (HHV), viscosity, molecular mass and chemical composition of bio-crude oil.
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