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[en] Two significant errors were found in this article: In Table 1, due to a missing decimal point, Dry Matter Yields are displayed ten times too high. In Figure 2, the caption of the y-axis should read kg CO2-equivalents ha−1a−1 instead of t CO2-equivalents ha−1a−1.
[en] The pyrolysis of wood fuel (WF) and polyethylenes (low-density polyethylene; LDPE and high-density polyethylene; HDPE) in a non-catalytic and catalytic co-pyrolysis over zeolite catalyst (ZSM-5) were studied via a thermogravimetric analysis. The result obtained for the biomass with LDPE and HDPE blends shows that the peak temperature decreases significantly only at blends with catalyst as compared to the peak temperature of isolated LDPE and HDPE materials. The peak temperature of WF/LDPE/ZSM-5 (390 °C) was lower than that of WF/HDPE/ZSM-5 (480 °C). The weight loss differences between experimental and theoretical values were greater than 1% at temperature higher than 500 °C in the various admixtures which depicts the occurrence of chemical interactions between the blends. After catalysts were added to the blend, the fuels became more reactive to thermal degradation. The results of the non-catalytic pyrolysis kinetics revealed activation energy values of 54.09 and 95.90 KJ/mol for WF/LDPE and WF/HDPE, respectively. However, with the presence of ZSM-5 activation, energy falls to 24.13 and 50.45 for WF/LDPE/ZSM-5 and WF/HDPE/ZSM-5, respectively. The findings in this work show that the kinetic of catalytic co-pyrolysis of biomass with plastic can be viewed as a potential thermochemical conversion method that can be effectively utilized for a marked reduction in energy requirement of the process.
[en] Vapor-phase hydrogenation of furfural is among the most industrially important biomass-based processes giving a vast range of products over different catalysts. In this paper, the effects of three modifiers (cobalt, chromium, and calcium) on the physicochemical properties of impregnated MgO-supported copper catalysts were evaluated for the first time using BET, XRD, SEM, EDX, and TG analyses. The performance of the catalysts was also assessed in terms of intrinsic activity and selectivity towards furfuryl alcohol. The cobalt- and chromium-promoted catalysts presented the highest conversion of furfural (75.1 and 68.8%) and high selectivity to furfuryl alcohol (96.9 and 98.5%) after 4 h of operation. The improvement by additives was more pronounced in the case of furfural conversion than furfuryl alcohol selectivity with respect to the unpromoted Cu/MgO catalyst (with a 54.5% conversion after 4 h). Overall, the Cu-Co/MgO was the most favored catalyst in terms of productivity to furfuryl alcohol. The addition of calcium showed a rather prohibitive influence on the activity of the base catalyst, however.
[en] Lignocellulosic materials represent a promising low-cost and abundant raw material which does not compete with foodstuffs, but an appropriate pretreatment is required to make sugars easily available. In this work, Eucalyptus grandis wood was subjected to autohydrolysis pretreatment under mild operational conditions (6–10 g/g liquid to solid ratio, 140–160 °C, reaction times up to 150 min) in order to recover and preserve hemicelluloses, while enhancing enzyme accessibility to cellulose. The severity of the pretreatment should be chosen depending on the subsequent use of the separated products. Pretreatment at 160 °C for 150 min using a liquid to solid ratio of 6 g/g was the best condition for hemicellulose recovery (mostly as xylose) in the liquid fraction. Under these autohydrolysis pretreatment conditions, an additional alkaline pretreatment applied to the autohydrolyzed solids was evaluated in order to improve the enzymatic hydrolysis of pretreated wood. Also, the addition of surfactant was assessed in order to enhance the enzymatic hydrolysis. The highest cellulose hydrolysis was obtained in the presence of PEG 6000. For the autohydrolysis-pretreated solids, a cellulose conversion of 39% was obtained, corresponding to an overall glucose yield of 18.7 kg per 100 kg of dry raw material. Additionally, for the autohydrolysis-alkaline-pretreated solids, a cellulose conversion of 43% was achieved, which corresponds to an overall glucose yield of 15.4 kg per 100 kg of dry raw material.
[en] The main goal of this work is to investigate if thermodynamic equilibrium calculations can be useful for understanding and predicting process performance and product composition for entrained flow gasification of spent pulping liquors, such as black liquor. Model sensitivity to input data is studied and model results are compared to published pilot plant data. The high temperature and the catalytic activity of feedstock alkali make thermodynamic equilibrium a better predictor of product composition than for many other types of biomass and gasification technologies. Thermodynamic equilibrium calculations can predict the flows of the main syngas and slag products with high accuracy as shown by comparison with experimental data with small measurement errors. The main process deviations from equilibrium are methane formation and sulfur distribution between gas and slag. In order to study real process deviations from equilibrium, it is very important to use consistent experimental data. Relatively small errors in the model input, primarily related to fuel composition, can lead to grossly erroneous conclusions. The model sensitivity to fuel composition also shows that the gasification process is sensitive to naturally occurring feedstock variations. Simulations of a commercial-scale gasification process show that cold gas efficiency on sulfur-free basis can reach over 80 % and that greatly improved efficiency can be obtained by reducing ballast present in the form of water or inorganics.
[en] In this study, gasification characteristics of histidine and 4-methylimidazole were investigated for the first time. A tubular flow reactor was employed, and experiments were conducted in the temperature range of 500–650 °C, at a fixed pressure of 25 MPa, with residence times of 86–119 s, and with 1.0 wt% aqueous solutions of histidine and 4-methylimidazole. The gaseous products were identified and quantified by gas chromatography (GC), and the aqueous phase was analyzed for total organic carbon (TOC). The gasification characteristics were compared with those of glycine and alanine, which represented the standard amino acid structure. The result showed that the carbon gasification efficiencies of both histidine and 4-methylimidazole increased with increasing reaction temperature. The gasification rate of 4-methylimidazole followed first-order kinetics and was explained well by the Arrhenius equation. The gasification rate for histidine could be predicted by the weighted summation of the adjusted gasification rates of glycine and 4-methylimidazole.
[en] Fish waste disposal is a major cause for concern for the seafood processing industries. Fish processing generates enormous quantities of waste as almost 45% of the live weight of fish is regarded as waste. Current ways of managing fish waste involves dumping in oceans, landfills, or treating them with already established strategies. Dumping these wastes without any form of treatment is far from being environmental friendly. Current utilization strategies suffer from disadvantages such as incomplete utilization of solid and liquid wastes or generation of new waste effluents that needs further processing. Therefore, there is a need to find an alternate/supplemental method of seafood utilization. Previously, we have reported the use of microwave hydrothermal carbonization (MHTC) to carbonize fish waste to hydrochar. Here, a conventional heating method such as a custom autoclave reactor is reported that could also be used to carbonize fish waste to hydrochar. Upon response surface design optimization, it was found that a maximal yield of hydrochar (~ 35%) can be achieved at a holding temperature of 180 °C and at a holding time of 120 min. We have also characterized the elemental, proximate, energy, and surface properties of hydrochar produced by conventional hydrothermal carbonization (CHTC). It was found that the quality of the hydrochar produced by MHTC is largely comparable to CHTC. This further proves that HTC could be employed to generate energy from non-lignocellulosic wastes such as fish waste while getting rid of the waste in an eco-friendly manner.
[en] The utilization of abundantly available lignocellulosic biomass requires an efficient cellulolytic enzyme system. Evaluation of an efficient microbial system is a crucial part for the development of useful enzyme production in an industrial process. The present study reports the production of cellulolytic enzymes from various lignocellulosic biomasses by Trichoderma harzianum strain HZN11 characterized by 18S rDNA sequencing. The organism revealed a well-balanced cellulolytic complex of enzyme production (endoglucanase 30.32 U g−1, exoglucanase 15.08 U g−1, FPase 5.56 U g−1, cellobiase 17.92 U g−1, β-glucosidase 11.21 U g−1, and xylanase 1740 U g−1) from sweet sorghum bagasse under solid-state fermentation. Statistical optimization by Plackett–Burman design constituting of 12 experimental runs at two levels of seven independent variables revealed the significant effect of four variables, namely, protease peptone, lactose, MgSO4·7H2O, and K2HPO4 on endoglucanase production at 95% confidence level with R2=97.68%. Response surface methodology using central composite design was employed with 31 experimental runs at 5 levels with 4 significant independent variables. The responses in the form of contour and 3D plots showed significant interaction effects. Significant interactions existed between the variables at p < 0.05 with R2=97.3%. The model generated through these designs was validated giving a 2.31-fold increase in endoglucanase production. The isolated T. harzianum strain HZN11 produced an efficient pool of cellulolytic enzymes which is essential for efficient hydrolysis of biomass. The strain HZN11 also possessed a significant capability of cellobiase production which is usually deficient in other strains. Higher yields of endoglucanase could be employed for bioethanol production.