Biomass Conversion and Biorefinery最新文献

Torrefaction or mild pyrolysis of woody biomass is a promising pretreatment step for pyrolysis or gasification. In the present study, torrefaction of hybrid poplar was carried out at the following process conditions: 190–300 °C temperature; 5–15 °C/min heating rate, and 10–60 min retention time. Hybrid poplar is a fast-growing woody biomass that is widely available and can conveniently be exploited to produce valuable biofuels. The objective was to optimize energy yield, elemental oxygen, and elemental carbon, considering the importance of deoxygenation and carbon densification. A response surface methodology was adopted to optimize and conduct further analysis. The optimized parameters were obtained at 274.89 °C temperature, 11.61 °C/min heating rate, and 10 min retention time. From this study, the deoxygenation and carbon densification were obtained to be 29.44 and 31.59%, respectively. The higher heating value of raw biomass increased by 29.38% due to torrefaction. The productions of CO and CO₂ were 69.55 and 30.44 vol%, respectively, for the optimized hybrid poplar.

This study investigated the effect of enzymatic hydrolysis using flavourzyme (FL) and alcalase (AL) at 1 or 3% E/S ratio on the hydrolysis efficiency and bio-functional properties of guar protein derived from guar meal (a byproduct of guar gum manufacturing industry). Hydrolysates were evaluated for the degree of hydrolysis (DH), protein yield, color, trichloroacetic acid (TCA) solubility, antioxidant activity (by DPPH, ABTS assays), SDS-PAGE patterns, and in vitro protein digestibility. The hydrolysate by AL at 3% E/S exhibited significantly higher (P < 0.05) DH (18.20%), protein yield (48.00%), and TCA solubility (62.80 ± 1.09%) compared to the hydrolysate by FL at 3% E/S (DH: 10.80%; protein yield: 43.27% and TCA solubility: 52.33%). Color analysis showed that the hydrolysate by FL at 3% E/S was lighter (L* = 29.23), while the hydrolysate by AL at 3% E/S was darker (L* = 27.42). The control (unhydrolyzed) sample exhibited a DPPH value of 14.24 and an ABTS value of 7.75 µmol TE/mg protein. Enzymatic hydrolysis significantly enhanced these properties, with the hydrolysate by AL at 3% E/S showed highest improvement ABTS and DPPH activity (65.14 and 32.32 µmol TE/mg protein, respectively), followed by the hydrolysate by FL at 3% E/S (60.22 and 28.47 µmol TE/mg protein, respectively). SDS-PAGE analysis revealed a more extensive breakdown of protein structures in AL-treated hydrolysates compared to control sample. Similarly, the control sample had an in vitro protein digestibility of 52.28%, which improved substantially after enzymatic hydrolysis, with the hydrolysate by AL at 3% E/S showing the highest digestibility (83.73%). These results suggest that enzymatic hydrolysis using FL and AL enhances bio-functional properties of guar protein, making it a promising ingredient for functional foods and nutraceuticals.

Global water pollution has significantly increased due to rapid industrialization with population growth, particularly in the textile sector, where artificial dyes and the discharge of coloring agents have risen sharply. This research explores the effectiveness of ZnO-incorporated biomaterial consisting of Musa paradisiaca (banana) peels in removing methylene blue dye from industrial effluents. The biosorbents tested were banana peel (Musa paradisiaca) powders, specifically in their raw form (UBP) and treated form (TBP). The batch-scale removal of dye was optimized using UBP at pH 6 and with TBP at pH 4. It was found that the optimal adsorbent doses were 1.2 g for UBP and 2.0 g for TBP. Among various isothermal models, the Temkin model yielded the best fit for the equilibrium experimental data. The adsorption process followed pseudo-second-order kinetics (R² = 0.9998 for UBP and 0.9996 for TBP), and further investigation into the adsorption mechanism was conducted through intra-particle diffusion studies which shows a more promising effect on TBP with maximum adsorption capacity of 32.341 mg/g. Thermodynamic parameters, including ΔG°, ΔS°, and ΔH° with values 4.508 kJ/mol at 283 K, 14.8604 cal/deg.mol, and 0.8722 kJ/mol respectively, were statistically computed for both biosorbents (UBP and TBP) indicating their endothermic and spontaneous nature.

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The development of new alternative adsorbents and the removal of pollutants in aqueous systems are essential to ensure the preservation of water quality, protect aquatic ecosystems and minimize public health risks, in addition to complying with increasingly stringent environmental regulations. In this study, long pepper leaves (INLP) were used to produce a carbonaceous adsorbent (LPAC), which was applied in the removal of methylene blue (MB) from water. This adsorbent was characterized by pH_pzc, SEM, FTIR, XRD and BET. The surface areas of INLP and LPAC were 1.26 and 59.3 m² g⁻¹, respectively. The removal tests indicated that the optimal pH value was 10.25 for MB adsorption on LPAC. MB/LPAC adsorption equilibrium was evaluated at 298 – 328 K. The Maximum equilibrium adsorption capacities were 86.5 ± 1.20; 85.56 ± 1.10; 85.28 ± 0.80; and 84.72 ± 0.84 mg g⁻¹ for tested operating conditions. MB removal decreased with increasing the aqueous solution temperature. Langmuir model fitted the experimental MB adsorption data (R² and R²_adj > 0.9971) suggesting a monolayer adsorption. Thermodynamically, this adsorption system was exothermic with ΔH° = -17.90 kJ mol⁻¹. PVSDM modeled MB adsorption kinetics on LPAC. The results indicated that the pore volume diffusion, surface diffusion and external mass transfer controlled the adsorption process of this dye molecule. DFT calculations obtained at the PBE-D3/Def2-SVP level of theory suggest a physisorption mechanism for MB adsorption, primarily governed by cation-π type electrostatic interaction. The total cost calculated to produce LPAC was 3.97 USD kg⁻¹. Thus, LPAC is also economically viable as a low-cost adsorbent.

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Pyrolysis is a promising method for converting biomass into energy. The present study focused on the air-limited pyrolysis of Pongamia pod husk (PPH) in a fixed bed reactor at varying temperatures, examining the resulting pyrolytic products. As the temperature increased, syngas production showed an increasing trend, while biochar production decreased. The bio-oil production showed a rising trend up to 600 °C, followed by a slight decline, likely due to the secondary cracking of the bio-oil into gases. Gas composition was investigated using GC-TCD, and biochar was characterized through FTIR, SEM, XRD, and CHN analysis. The air-limited pyrolysis process produced hydrogen-rich syngas, with a maximum yield of 39.22 ± 0.31% at 700 °C after 8 h. Biochar obtained at 700 °C had a carbon content of 77.22%. Compositional analysis of bio-oil revealed the presence of various components, including aliphatic and aromatic hydrocarbons, phenolic compounds, nitrogen compounds, nitriles, and oxygen-containing compounds such as acids, fatty acid esters, and ketones. The syngas produced from PPH pyrolysis could be used as fuel or converted into liquid fuels like methanol, while biochar has applications in agriculture, industrial catalysis, and bioremediation. Additionally, bio-oil may be upgraded into valuable fuels.

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Rhodamine B dye contamination poses serious environmental and health risks due to its carcinogenic and neurotoxic properties. This study explores the use of alkaline-treated human hair as a low-cost adsorbent for dye removal from water. The hair was treated with 0.1 M sodium hydroxide, rinsed, and dried to enhance its adsorption capacity. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of key functional groups such as hydroxyl, carboxyl, and amine groups, which facilitate dye binding. Scanning electron microscopy (SEM) revealed surface modifications after treatment. The effects of contact time, initial dye concentration, and adsorbent dose were analyzed using a central composite design under response surface methodology. Optimal conditions—34.66 mg/L initial concentration, 3.5 g adsorbent dose, and 20.59 min contact time—achieved a maximum removal efficiency of 85.71 ± 0.61%. The adsorption followed the Langmuir isotherm (R² = 0.99426) and pseudo-second-order kinetics (R² = 0.98211), indicating a monolayer and chemisorption mechanism. The maximum adsorption capacity based on optimal conditions was 4.95 mg/g. The findings suggest that human hair could be a viable adsorbent in removing dye from contaminated water.

The large amounts of combustible materials stored in forests can serve as potential biomass fuels for energy conversion. The pyrolysis dynamics in dry and wet forest biomass, as well as the biomass types affecting the energy conversion efficiency remain unclear. In this study, the pyrolysis characteristics of three biomass wastes (pine needles, decayed leaves, and peat mosses) from different forest layers (litter, duff, and organic soil) in both dry and wet conditions were experimentally investigated using thermo-gravimetric analysis, and were modeled by a parallel reaction scheme encompassing water evaporation, hemicellulose, cellulose, and lignin degradation. Higher moisture caused a narrower decomposition temperature zone of organic matter, influencing the yields of volatiles during pyrolysis. The final temperature of pyrolysis stage of main organic matter in wet samples occurred prior to that in dry samples (approximately 5–49 K). The kinetic model showed that lignin decomposition presented the lowest values (10.05 kJ mol⁻¹) in terms of the discrepancy in activation energies among the samples. Moreover, the activation energy (48.93 ± 2.78 kJ mol⁻¹) of water evaporation was found to be similar not only among biomasses, but also between the dry and wet conditions. This study contributes to an enhanced understanding of the pyrolysis capacity and energy utilization potential of dry and wet biomasses from different forest layers.

Sludge is the main solid waste generated within the mill. The effluent treatment plant usually generates primary (PS) and secondary sludge (SS). PS is rich in cellulose fibers and SS is rich in bacterial cells. SS is more difficult to dewater and is often mixed with the PS to help drainage. Currently, the main way for disposal is landfilling or incineration without any pre-treatment. New processes are required to seek a more circular economy and maximum use of all co-products. Pelletization is a simple process that allows the standardization and increase of energy density of the biomass. This work aimed to produce pellets using various blends of PS and SS generated at a kraft pulp mill (100% PS, 75% PS, 50% PS, 25% PS, 0% PS) and testing different moisture content, on a wet basis (10%, 25%, 40%). The sludge was subject to elemental characterization, proximate analysis, heating value, thermal degradation evaluation, and ash melting behavior analysis. The increase of secondary sludge increased the ash content of the pellets. The ash melting temperature of the sludges was higher than the typical operating temperatures of boilers. The sludge had a higher heating value (16.2—17.4 MJ.kg⁻¹). The pellets produced using the blend of 75% PS + 25% SS with a moisture content of 25% presented low fines generation (0.043%) and high durability (99.3%). The pellets produced with 100% SS at 40% moisture showed the lowest resistance. The pelletization process was a suitable alternative for managing pulp mill sludge.

Deep eutectic solvents (DESs) are attractive for lignocellulosic biomass deconstruction because of their easy synthesis, reusability, inexpensive nature, and eco-friendliness. Pretreatment of rice straw was carried out using three types of DES: choline chloride:glycerol (ChCl:Gly), choline chloride:ethylene glycol (ChCl:EG), and choline chloride:formic acid (ChCl:FA) at 120 °C, 1.5 bars in an autoclave for 1 h. Enzymatic digestibility of pretreated samples was assessed at 10% solids loading and 9.0 filter paper units g⁻¹ cellulose of enzyme loading. A delignification efficiency of 51.6% was obtained with ChCl:FA compared to 30.4% and 36.1% obtained with ChCl:Gly and ChCl:EG respectively. The cellulose content of 58.4% was obtained from ChCl:FA pretreated samples compared to cellulose contents of < 48% from ChCl:Gly and ChCl:EG pretreated samples; cellulose content of pretreated and untreated samples correlated with their crystallinity indexes. The lowest hemicellulose content of 9.5% was obtained from the ChCl:FA pretreated sample, while ChCl:Gly and ChCl:EG were like the untreated (around 22%). As indicated by spectroscopic, microscopic, and thermogravimetric analysis, DES pretreatment caused alterations in chemical composition, structure, and surface morphology. ChCl:FA pretreated sample (Ac-PT4) was significantly hydrolysed, resulting in a glucose yield of 79.7% and a concentration of 45.56 gLl⁻¹ after 72 h of hydrolysis. The glucose yield obtained from ChCl:Gly and ChCl:EG pretreated samples ranged from 32 to 36%, while the glucose concentrations ranged from 14 to 16 gL⁻¹. Pretreatment using ChCl:FA effectively delignified rice straw and led to a threefold increase in enzymatic digestibility compared to untreated; hence, pretreatment using ChCl:FA could support a biorefinery concept.

Renewable and sustainable biomass materials have begun to be used in many new areas. In this context, lignocellulosic wastes such as hazelnut shells (HS), sunflower seed shells (SSS), and rice hulls (RH) were activated chemically using a base (KOH) or a salt (ZnCl₂) followed by physical activation at 800–900 °C. Then, carbon aerogels were produced from these pre-activated biomasses and used to prepare symmetrical supercapacitor (SS) electrodes. Electrochemical tests of SSs were performed using the potentiostat/galvanostat where the reference electrode and counter electrode for the three-electrode system were an Ag/AgCl electrode and a Pt wire, respectively, and the electrolyte was 0.5 M H₂SO₄ /PVA gelled. Although the specific surface area of the aerogel produced from ZnCl₂-activated SSS was only 137 m²/g, it provided a specific capacitance of 275.11 F/g at a scan rate of 5 mV/s and a long cycle test comprising 10,000 cycles, while the aerogel produced from ZnCl₂-activated HS with specific surface area of 1154 m²/g showed lower electrochemical potential. Besides, the electrochemical performance of KOH-activated HS outperformed the KOH-activated SSS. It is concluded that to prepare aerogels that have high specific capacity, biomass with high holocellulose- and extractive substances- content (like SSS) should be activated by ZnCl₂, while biomass with high lignin content (like HS) should be activated by KOH. It is also concluded that only the specific surface area can not predict the specific capacitance and other factors such as having a hierarchical pore structure and having a suitable surface chemistry may be more decisive.

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