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  • 1.
    Cavka, Adnan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Martin, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Alriksson, Bjorn
    Mortsell, Marlene
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Techno-economic evaluation of conditioning with sodium sulfite for bioethanol production from softwood2015In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 196, p. 129-135Article in journal (Refereed)
    Abstract [en]

    Conditioning with reducing agents allows alleviation of inhibition of biocatalytic processes by toxic by-products generated during biomass pretreatment, without necessitating the introduction of a separate process step. In this work, conditioning of steam-pretreated spruce with sodium sulfite made it possible to lower the yeast and enzyme dosages in simultaneous saccharification and fermentation (SSF) to 1 g/L and 5 FPU/g WIS, respectively. Techno-economic evaluation indicates that the cost of sodium sulfite can be offset by benefits resulting from a reduction of either the yeast load by 0.68 g/L or the enzyme load by 1 FPU/g WIS. As those thresholds were surpassed, inclusion of conditioning can be justified. Another potential benefit results from shortening the SSF time, which would allow reducing the bioreactor volume and result in capital savings. Sodium sulfite conditioning emerges as an opportunity to lower the financial uncertainty and compensate the overall investment risk for commercializing a softwood-to-ethanol process. (C) 2015 The Authors. Published by Elsevier Ltd.

  • 2. de Albuquerque Wanderley, Maria Carolina
    et al.
    Martín, Carlos
    Department of Chemistry and Chemical Engineering, University of Matanzas, Matanzas, Cuba; vTI-Institute for Wood Technology and Wood Biology, Hamburg, Germany.
    de Moraes Rocha, George Jackson
    Gouveia, Ester Ribeiro
    Increase in ethanol production from sugarcane bagasse based on combined pretreatments and fed-batch enzymatic hydrolysis2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 128, p. 448-453Article in journal (Refereed)
    Abstract [en]

    Enzymatic hydrolysis of pretreated sugarcane bagasse was performed to investigate the production of ethanol. The sugarcane bagasse was pretreated in a process combining steam explosion and alkaline delignification. The lignin content decreased to 83%. Fed-batch enzymatic hydrolyses was initiated with 8% (w/v) solids loading, and 10 FPU/g cellulose. Then, 1% solids were fed at 12, 24 or 48 h intervals. After 120 h, the hydrolysates were fermented with Saccharomyces cerevisiae UFPEDA 1238, and a fourfold increase in ethanol production was reached when fed-batch hydrolysis with a 12-h addition period was used for the steam pretreated and delignified bagasse.

  • 3. de Moraes Rocha, George Jackson
    et al.
    Nascimento, Viviane Marcos
    Goncalves, Adilson Roberto
    Nunes Silva, Vinicius Fernandes
    Martín, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Influence of mixed sugarcane bagasse samples evaluated by elemental and physical-chemical composition2015In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 64, p. 52-58Article in journal (Refereed)
    Abstract [en]

    Brazil, with 185 million tons of solid residues generation per harvest, is the largest producer of sugarcane in the world. The utilization of this biomass ranges from the extraction of sugarcane juice for application in the ethanol and sugar industry to energy generation and bio-based products synthesis. Sugarcane residues are basically composed of hemicellulose, cellulose and lignin chemical structures that are tightly linked to each other and are responsible for the integrity of the vegetal biomass. The aim of the present work is to show the different relations of the biomass contents from different varieties, cultivated places, soils, harvest season, and climate. For the chemical and elemental determination, 60 bagasse samples were characterized. The different bagasse samples did not show significant variability in their lignocellulosic contents. The results showed that the biomass characterization is an important step to obtain process characteristics.

  • 4.
    Gandla, Madhavi Latha
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. KBC Chemical-Biological Centre, Umeå University.
    Martin, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry. KBC Chemical-Biological Centre, Umeå University.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. KBC Chemical-Biological Centre, Umeå University.
    Analytical Enzymatic Saccharification of Lignocellulosic Biomass for Conversion to Biofuels and Bio-Based Chemicals2018In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 11, article id 2936Article, review/survey (Refereed)
    Abstract [en]

    Lignocellulosic feedstocks are an important resource for biorefining of renewables to bio-based fuels, chemicals, and materials. Relevant feedstocks include energy crops, residues from agriculture and forestry, and agro-industrial and forest-industrial residues. The feedstocks differ with respect to their recalcitrance to bioconversion through pretreatment and enzymatic saccharification, which will produce sugars that can be further converted to advanced biofuels and other products through microbial fermentation processes. In analytical enzymatic saccharification, the susceptibility of lignocellulosic samples to pretreatment and enzymatic saccharification is assessed in analytical scale using high-throughput or semi-automated techniques. This type of analysis is particularly relevant for screening of large collections of natural or transgenic varieties of plants that are dedicated to production of biofuels or other bio-based chemicals. In combination with studies of plant physiology and cell wall chemistry, analytical enzymatic saccharification can provide information about the fundamental reasons behind lignocellulose recalcitrance as well as about the potential of collections of plants or different fractions of plants for industrial biorefining. This review is focused on techniques used by researchers for screening the susceptibility of plants to pretreatment and enzymatic saccharification, and advantages and disadvantages that are associated with different approaches.

  • 5. Garcia, Ariel
    et al.
    Lopez, Yoney
    Karimi, Keikhosro
    Benitez, Agustin
    Lundin, Magnus
    Taherzadeh, Mohammad
    Martín, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry. *Department of Chemistry and Chemical Engineering, University of Matanzas, Matanzas 44740, Cuba.
    Chemical and physical characterization and acid hydrolysis of a mixture of Jatropha Curcas shells and husks2015In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 49, no 9-10, p. 737-744Article in journal (Refereed)
    Abstract [en]

    Jatropha curcas L. is a tropical plant with considerable potential for producing biodiesel and other products of high economic and social interest. During the biodiesel production process from J. curcas different residues, such as shells and husks are generated. In this work, the physical characterization of J. curcas fruits was performed, and the chemical composition of a mixture of shells and husks was determined. The physical characterization revealed that shells and husks account, respectively, for 25.0 and 27.8% of the fruit weight. The compositional analyses of the material showed a quite high content of glucans (32.8% w/w) and xylans (16.4% w/w), which indicates the potential of J. curcas shells and husks for production of ethanol, xylitol and other glucose- and xylose-derived products. Acid hydrolysis was applied to a mixture of shells and husks under different sulphuric acid concentrations (from 0.5 to 4.5%), temperatures (170-220 degrees C) and time (10-20 min), and the hydrolytic conversion of xylan was evaluated. A zone of experimental conditions giving maximal xylan conversion was identified at around 4% H2SO4, 180 degrees C and reaction time below 10 min.

  • 6. García, Ariel
    et al.
    Cara, Cristóbal
    Moya, Manuel
    Rapado, Jorge
    Puls, Jürgen
    Castro, Eulogio
    Martín, Carlos
    Departament of Chemistry and Chemical Engineering, University of Matanzas, 44740 Matanzas, Cuba.
    Dilute sulphuric acid pretreatment and enzymatic hydrolysis of Jatropha curcas fruit shells for ethanol production2014In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 53, p. 148-153Article in journal (Refereed)
    Abstract [en]

    Abstract Jatropha curcas is a promising source of oil for the biodiesel industry, and the shells of its fruits could be considered for ethanol production. In this work, the composition of J. curcas shells is investigated, and the potential of dilute-sulphuric acid pretreatment for improving the enzymatic hydrolysis of cellulose is evaluated. A Box–Behnken experimental design was used for assessing the effect of temperature (110–150 °C), H2SO4 concentration (0.5–2.5%) and pretreatment time (15–45 min) on the formation of sugars during pretreatment and on the enzymatic conversion of cellulose. Cellulose conversions above 80% were achieved both in the separated enzymatic hydrolysis and in the simultaneous saccharification and fermentation of the pretreated materials. Optimal SSF conversions were predicted for pretreatments at low temperature (136 °C) and moderate acid concentrations (1.5%) and reaction time (30 min). The inclusion of an extraction step prior to the pretreatment revealed a further improvement of the enzymatic conversion of cellulose.

  • 7. Hernández, Ena
    et al.
    García, Ariel
    López, Michael
    Puls, Jürgen
    Parajó, Juan C.
    Martín, Carlos
    Department of Chemistry and Chemical Engineering, University of Matanzas, 44740 Matanzas, Cuba.
    Dilute sulphuric acid pretreatment and enzymatic hydrolysis of Moringa oleifera empty pods2013In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 44, p. 227-231Article in journal (Refereed)
    Abstract [en]

    In this work, dilute sulphuric acid prehydrolysis of residual empty pods of Moringa oleifera fruits was investigated as pretreatment for enzymatic hydrolysis of cellulose. In experiments performed at 130–190 °C for 10–30 min, corresponding to a severity range between log Ro = 1.9 and log Ro = 4.2, the effect of pretreatment conditions on the recovery of polysaccharides and on the enzymatic convertibility of cellulose was evaluated. Overall cellulose recovery was above 95% in the pretreatments performed at 130 and 160 °C, and between 87 and 90% in the pretreatments at 190 °C, while xylan recovery in the most severe pretreatments was only 24.7–50.2%. The highest sugar concentration in the acid prehydrolysates (15.0 g/L) was obtained in the pretreatment performed at 160 °C and 20 min. The formation of degradation products was low at mild pretreatment conditions, but it increased with the severity. Furfural concentration reached 4.04 g/L at log Ro = 3.1 and decreased again with a further increase of the pretreatment severity. HMF, formic acid and levulinic acid were formed only in the most severe pretreatments. The pretreatment was effective for improving the enzymatic hydrolysis of cellulose, and the highest conversion (84.3%) was achieved in the material pretreated at mid severity (log Ro = 3.1).

  • 8.
    Jonsson, Leif J.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Martin, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pretreatment of lignocellulose: Formation of inhibitory by-products and strategies for minimizing their effects2016In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 199, p. 103-112Article, review/survey (Refereed)
    Abstract [en]

    Biochemical conversion of lignocellulosic feedstocks to advanced biofuels and other commodities through a sugar-platform process involves a pretreatment step enhancing the susceptibility of the cellulose to enzymatic hydrolysis. A side effect of pretreatment is formation of lignocellulose-derived by-products that inhibit microbial and enzymatic biocatalysts. This review provides an overview of the formation of inhibitory by-products from lignocellulosic feedstocks as a consequence of using different pretreatment methods and feedstocks as well as an overview of different strategies used to alleviate problems with inhibitors. As technologies for biorefining of lignocellulose become mature and are transferred from laboratory environments to industrial contexts, the importance of management of inhibition problems is envisaged to increase as issues that become increasingly relevant will include the possibility to use recalcitrant feedstocks, obtaining high product yields and high productivity, minimizing the charges of enzymes and microorganisms, and using high solids loadings to obtain high product titers.

  • 9.
    Lima, David Albuquerque
    et al.
    Recife, PE, Brazil.
    Nogueira De Luna, Rafaela Lira
    Recife, PE, Brazil.
    Martin, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Univ Matanzas, Dept Chem & Chem Engn, Matanzas 44740, Cuba.
    Gouveia, Ester Rbeiro
    Recife, PE, Brazil.
    Comparison of bioethanol production from acid hydrolyzates of waste office paper using saccharomyces cerevisiae and spathaspora passalidarum2015In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 49, no 5-6, p. 463-469Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to evaluate waste office paper as raw material for bioethanol productionusing four strains of Saccharomyces cerevisiae and Spathasporapassalidarum HMD 14.2.Waste paper was hydrolyzed with 1-5% V/V sulfuric acid to 2-10% w/Vbiomass load for 60-120 min. The most significant variable for the total reduced sugar (TRS) was the biomass load, followed by the acid concentration. The pretreatment time did not exert any significant effect on TRS. The hydrolysate obtained with 5% V/V sulfuric acid, 10% w/V biomass load and 1 hour, containing8.45 g/L glucose and 9.27 g/L xylose, was chosen for the fermentations. The fermentation with S. passalidarum resulted in higher ethanol formation (3.54 g/L) than the fermentation with S. cerevisiae, which corresponds to a hypothetical yield of 0.708 g/g glucose. This indicates that S. passalidarum produces ethanol not only from glucose, but also from xylose.

  • 10.
    Martin, Carlos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Garcia, Ariel
    Schreiber, Andreas
    Puls, Juergen
    Saake, Bodo
    Combination of water extraction with dilute-sulphuric acid pretreatment for enhancing the enzymatic hydrolysis of jatropha curcas shells2015In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 64, p. 233-241Article in journal (Refereed)
    Abstract [en]

    Jatropha curcas shells were extracted with water in a pilot-scale reactor and then pretreated with dilute sulphuric acid. The pretreatment was initially investigated with a Box-Behnken experimental design in the range of 110-180 degrees C, 0.1-1.5% H2SO4 and 20-60 min, and then with complementary experiments at 190 degrees C. The glucan recovery was above 87% in all the experimental runs. Xylan solubilisation was 13-20% in the milder pretreatments and up to 45% in the most severe runs. Around 70% cellulose enzymatic conversion, evaluated with commercial cellulases during 72-h hydrolysis, was achieved for the pretreatments at 180 degrees C, and a region with maximal conversion was predicted for around 190 degrees C. For confirming that estimation, a 2(2)-experiment augmented by one central point and parallel pretreatments of pre-extracted and non-extracted shells were performed. The highest cellulose conversion, reached at the central point, was 16.5% higher for the pre-extracted and pretreated material than for the directly pretreated one. The low cellulose crystallinity index (0.79) of the pre-extracted and pretreated shells correlated well with their better enzymatic convertibility.

  • 11.
    Martin, Carlos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. A.N Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow 119071, Russia; Thünen Institute for Wood Research, 21031 Hamburg, Germany .
    Volkov, Pavel V.
    Rozhkova, Aleksandra M.
    Puls, Juergen
    Sinitsyna, Arkady P.
    Comparative study of the enzymatic convertibility of glycerol- and dilute acid-pretreated sugarcane bagasse using Penicillium- and Trichoderma-based cellulase preparations2015In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 77, p. 382-390Article in journal (Refereed)
    Abstract [en]

    Three enzyme preparations based on the cellulase complex of Penicillium verruculosum and three Trichoderma reesei-based enzyme cocktails were used for evaluating the enzymatic convertibility of cellulose contained in glycerol- and sulfuric acid-pretreated bagasse. The hydrolysis was initially monitored with a micro-scale method using 2 mL of reaction mixture containing 50 g/L of pretreated solids, and at an enzyme load of 10 mg proteinig cellulose. The results were further validated at a higher scale in a setup consisting of 20 mL of reaction mixture with a substrate concentration of 100 g/L. For all the cellulase preparations, and regardless of the experiment scale, glycerol-pretreated bagasse displayed better enzymatic convertibility than acid-pretreated bagasse. It was observed that when the enzyme load is increased from 2 to 10 mg/g, the cellulose conversion is improved but the specific hydrolysis rate is only marginally affected. Although the Trichoderma-based commercial cocktail CC-3 led to higher hydrolysis rates and conversions than all the other enzyme preparations, the Penicillium-based cellulases, especially PV-Xyl PCA and PV-Hist BGL, also showed good potential. PV-Xyl PCA was relatively effective for hydrolysing acid-pretreated bagasse, and PV-Hist BGL displayed reasonable performance in the hydrolysis in absence of exogenous beta-glucosidase. 

  • 12.
    Martín, Carlos
    et al.
    Department of Chemistry and Chemical Engineering, University of Matanzas, 44740 Matanzas, Cuba.
    Jürgen, Puls
    Andreas, Schreiber
    Bodo, Saake
    Optimization of sulfuric acid-assisted glycerol pretreatment of sugarcane bagasse2013Other (Other academic)
    Abstract [en]

    A combined pretreatment of sugarcane bagasse with glycerol and sulfuric acid was investigated based on a central composite rotatable experimental design. The following factors were varied: temperature (150–199°C), time (0.69–2.3 h), H2SO4 concentration (0.0–1.1%), and glycerol concentration (55.4–79.6%). Xylans and lignin were considerably solubilized during pretreatment. Xylan solubilization, ranging between 6% and 94%, increased significantly with the increase of temperature, time, and H2SO4 concentration and dropped with the increase of glycerol amount. Glycerol restricted the solubilization and full hydrolysis of xylans and the degradation of xylose. Lignin solubilization (20.6–49.4%) increased with the increase of all the experimental factors. Cellulose recovery, which was generally high, increased with the increasing of glycerol concentration and declined at high levels of the other factors. Recoveries above 97% were achieved at low H2SO4 concentration and high glycerol load, whereas the lowest value (83.4%) was achieved in the longest-lasting experiment. The models based on the experimental results predicted the maximal lignin solubilization at 187.7°C, 2.3 h, 79.6% glycerol, and 0.64% H2SO4, whereas the highest yield of enzymatic hydrolysis can be expected at 194.1°C, 1.67 h, 79.6% glycerol, and 1.1% H2SO4. The optimal conditions were confirmed in control experiments. The synergistic effect of sulfuric acid and glycerol on the enzymatic hydrolysis of cellulose was demonstrated.

  • 13.
    Martín, Carlos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Peinemann, Jan Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wei, Maogui
    Stagge, Stefan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Xiong, Shaojun
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Dilute-sulfuric acid pretreatment of de-starched cassava stems for enhancing the enzymatic convertibility and total glucan recovery2019In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 132, p. 301-310Article in journal (Refereed)
    Abstract [en]

    Cassava stems are an abundant feedstock that is becoming attractive for biochemical conversion to fuels and chemicals. Since cassava stems are rich in both cellulose and starch, carefully designed pretreatment and digestion procedures are required for achieving high glucan recovery. In this study, partially de-starched cassava stems resulting from a water extraction stage were hydrolyzed with amylases, and the resulting starch-depleted material was pretreated with dilute sulfuric acid, and submitted to enzymatic hydrolysis of cellulose. The effects of acid pretreatment on glucan recovery, enzymatic convertibility, and by-product formation were investigated using a Box-Behnken experimental design with temperature (165-195 degrees C), time (5-35 min), and acid concentration (0.2-1.0%) as independent variables. In further experimental series, the time period was extended up to 110 min while maintaining temperature at 195 degrees C and sulfuric acid concentration at 0.6%. Using those conditions, pretreatment for 50 min gave the best results (83.8% enzymatic convertibility of pretreated cellulose, and (similar to)72% overall glucan-to-glucose conversion).

  • 14.
    Martín, Carlos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wei, Maogui
    Xiong, Shaojun
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Enhancing saccharification of cassava stems by starch hydrolysis prior to pretreatment2017In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 97, p. 21-31Article in journal (Refereed)
    Abstract [en]

    Chemical characterization of cassava stems from different origin revealed that glucans accounted for 54-63% of the dry weight, whereas 35-67% of these glucans consisted of starch. The cassava stems were subjected to a saccharification study including starch hydrolysis, pretreatment with either sulfuric acid or 1-ethyl-3-methylimidazolium acetate ([Emim]OAc), and enzymatic hydrolysis of cellulose. Starch hydrolysis prior to pretreatment decreased sugar degradation, improved enzymatic convertibility of cellulose, and increased overall glucan conversion. Glucan recovery after pretreatment of starch-free cassava stems (SFCS) was around 85%, but below 52% when the stems were pretreated under the same conditions without preparatory starch hydrolysis. The total amount of hydrolyzed glucan after cellulose hydrolysis was two-fold higher for pretreated SFCS than for directly pretreated stems. Pretreatment with [Emim]OAc resulted in 20% higher glucan conversion than pretreatment with acid. Pyrolysis-GC/MS, X-ray diffraction, CP/MAS C-13 NMR and FTIR analyses revealed major differences between H2SO4- and [Emim]OAc-pretreated material. 

  • 15.
    Martín, Carlos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wu, Guochao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wang, Zhao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Stagge, Stefan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Formation of microbial inhibitors in steam-explosion pretreatment of softwood impregnated with sulfuric acid and sulfur dioxide2018In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 262, p. 242-250Article in journal (Refereed)
    Abstract [en]

    Wood chips of Norway spruce were pretreated by steam explosion at 195–215 °C after impregnation with either sulfuric acid (SA) or sulfur dioxide (SD). The effects of different pretreatment conditions on formation of microbial inhibitors were investigated, and the inhibitory effects on yeast of pretreatment liquids and of specific inhibitors that were found in the pretreatment liquids were elucidated. Whereas the concentrations of most inhibitors increased with increasing pretreatment temperatures, there were exceptions, such as formaldehyde and p-hydroxybenzaldehyde. The highest concentration of each inhibitor was typically found in SD-pretreated material, but formic acid was an exception. The toxic effects on yeast were studied using concentrations corresponding to loadings of 12 and 20% total solids (TS). Among individual inhibitors that were quantitated in pretreatment liquids, the concentrations of formaldehyde were by far most toxic. There was no or minimal yeast growth in the formaldehyde concentration range (5.8–7.7 mM) corresponding to 12% TS.

  • 16. Oliveira, Fernando M.V.
    et al.
    Pinheiro, Irapuan O.
    Souto-Maior, Ana M.
    Martin, Carlos
    Department of Chemistry and Chemical Engineering, University of Matanzas, Matanzas 44740, Cuba.
    Gonçalves, Adilson R.
    Rocha, George J.M.
    Industrial-scale steam explosion pretreatment of sugarcane straw for enzymatic hydrolysis of cellulose for production of second generation ethanol and value-added products2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 130, p. 168-173Article in journal (Refereed)
    Abstract [en]

    Steam explosion at 180, 190 and 200 °C for 15 min was applied to sugarcane straw in an industrial sugar/ethanol reactor (2.5 m3). The pretreated straw was delignificated by sodium hydroxide and hydrolyzed with cellulases, or submitted directly to enzymatic hydrolysis after the pretreatment. The pretreatments led to remarkable hemicellulose solubilization, with the maximum (92.7%) for pretreatment performed at 200 °C. Alkaline treatment of the pretreated materials led to lignin solubilization of 86.7% at 180 °C, and only to 81.3% in the material pretreated at 200 °C. All pretreatment conditions led to high hydrolysis conversion of cellulose, with the maximum (80.0%) achieved at 200 °C. Delignification increase the enzymatic conversion (from 58.8% in the cellulignin to 85.1% in the delignificated pulp) of the material pretreated at 180 °C, but for the material pretreated at 190 °C, the improvement was less remarkable, while for the pretreated at 200 °C the hydrolysis conversion decreased after the alkaline treatment.

  • 17. Rocha, George J. M.
    et al.
    Silva, Vinícius F. N.
    Martín, Carlos
    Department of Chemistry and Chemical Engineering University of Matanzas Matanzas Cuba.
    Gonçalves, Adilson R.
    Nascimento, Viviane Marcos
    Souto-Maior, Ana M.
    Effect of Xylan and Lignin Removal by Hydrothermal Pretreatment on Enzymatic Conversion of Sugarcane Bagasse Cellulose for Second Generation Ethanol Production2013In: Sugar Tech, ISSN 0974-0740, Vol. 15, no 4, p. 390-398Article in journal (Refereed)
    Abstract [en]

    This work was aimed to evaluate the effect of the removal of hemicellulose and lignin, by hydrothermal pretreatment, carried out at four different temperatures, namely 180, 185, 190 and 195 °C, for 10 min in a 20-L reactor, and alkaline delignification with 1.0 % (w/v) NaOH, at 100 °C for 1 h, on the enzymatic saccharification of sugarcane bagasse cellulose. For the material pretreated under the most severe conditions (1.0 % (w/v) NaOH, 100 °C, 1 h and 195 °C, 10 min), 95.8 % of the hemicellulosic fraction and 80.9 % of lignin were solubilised upon pretreatment and delignification respectively. The enzymatic conversion of the material obtained under those conditions reached 89.2 % of the initial cellulose, whereas it was 69.2 % for the pretreated but non-delignified material and only 6.0 % for raw bagasse. Models describing the effect of hemicellulose and lignin content on the enzymatic hydrolysis were developed. The statistical analysis of the results emphasized the significance of removal of the hemicellulose and lignin for improving the enzymatic hydrolysis of cellulose.

  • 18.
    Soudham, Venkata Prabhakar
    et al.
    School of Engineering, University of Borås, Borås, Sweden and Bioresource Technology Group, Department of Chemistry and Chemical Engineering, University of Matanzas, Matanzas, Cuba.
    Rodriguez, Dani
    Bioresource Technology Group, Department of Chemistry and Chemical Engineering, University of Matanzas, Matanzas, Cuba.
    Rocha, George J M
    Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, Brazil.
    Taherzadeh, Mohammad J
    School of Engineering, University of Borås, Borås, Sweden.
    Martin, Carlos
    Bioresource Technology Group, Department of Chemistry and Chemical Engineering, University of Matanzas, Matanzas, Cuba.
    Acetosolv delignifi cation of marabou (Dichrostachys cinerea) wood with and without acid prehydrolysis2011In: Forest Science, ISSN 0015-749X, E-ISSN 1938-3738, Vol. 13, no 1, p. 64-70Article in journal (Refereed)
    Abstract [en]

    The chemical composition of marabou (Dichrostachys cinerea) wood and its treatment with acetic acid were investigated. Two different treatment approaches, direct acetosolv and combined acid prehydrolysis/acetosolv, were evaluated. The effects of acetic acid concentration (50%, 70% and 90%) and temperature (normal boiling temperature and 121°C) on yield of solids, solubilization of lignin and hemicelluloses and recovery of cellulose were evaluated for both treatments. High solubilization of marabou components was observed in the direct acetosolv treatment at 121°C, especially at the highest acetic acid concentration, where around 84.8% of lignin and 78% of hemicelluloses were removed. When the material was subjected to acid prehydrolysis prior to acetosolv treatment, lignin solubilization was improved, especially at low acetic acid concentrations. Above 80% of the solubilized lignin was recovered from the liquors in the direct acetosolv treatment, but the recovery was lower in the combined treatment. Cellulose was well preserved in all the treatment schemes.

  • 19. Xiong, Shaojun
    et al.
    Martin, Carlos
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eilertsen, Lill
    Wei, Maogui
    Myronycheva, Olena
    Larsson, Sylvia H.
    Lestander, Torbjorn A.
    Atterhem, Lars
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Energy-efficient substrate pasteurisation for combined production of shiitake mushroom (Lentinula edodes) and bioethanol2019In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 274, p. 65-72Article in journal (Refereed)
    Abstract [en]

    Hot-air (75-100 degrees C) pasteurisation (HAP) of birch-wood-based substrate was compared to conventional autoclaving (steam at 121 degrees C) with regard to shiitake growth and yield, chemical composition of heat-pretreated material and spent mushroom substrate (SMS), enzymatic digestibility of glucan in SMS, and theoretical bioethanol yield. Compared to autoclaving, HAP resulted in faster mycelial growth, earlier fructification, and higher or comparable fruit-body yield. The heat pretreatment methods did not differ regarding the fractions of carbohydrate and lignin in pretreated material and SMS, but HAP typically resulted in lower fractions of extractives. Shiitake cultivation, which reduced the mass fraction of lignin to less than half of the initial without having any major impact on the mass fraction of glucan, enhanced enzymatic hydrolysis of glucan about four-fold. The choice of heating method did not affect enzymatic digestibility. Thus, HAP could substitute autoclaving and facilitate combined shiitake mushroom and bioethanol production.

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