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Martin C.,University of Matanzas | Martin C.,VTI Institute for Wood Technology and Wood Biology | De Moraes Rocha G.J.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Dos Santos J.R.A.,Federal University of Pernambuco | And 2 more authors.
Quimica Nova | Year: 2012

The enzymatic hydrolysis of steam-pretreated sugarcane bagasse, either delignified or non-delignified, was studied as a function of enzyme loading. Hydrolysis experiments were carried out using five enzyme loadings (2.5 to 20 FPU/g cellulose) and the concentration of solids was 2% for both materials. Alkaline delignification improved cellulose hydrolysis by increasing surface area. For both materials, glucose concentrations increased with enzyme loading. On the other hand, enzyme loadings higher than 15 FPU/g did not result in any increase in the initial rate, since the excess of enzyme adsorbed onto the substrate restricted the diffusion process through the structure.

Wanderley M.C.D.A.,Federal University of Pernambuco | Martin C.,University of Matanzas | Martin C.,VTI Institute for Wood Technology and Wood Biology | Rocha G.J.D.M.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Gouveia E.R.,Federal University of Pernambuco
Bioresource Technology | Year: 2013

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. © 2012 Elsevier Ltd.

Rocha G.J.M.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Silva V.F.N.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Silva V.F.N.,University of Sao Paulo | Martin C.,University of Matanzas | And 4 more authors.
Sugar Tech | Year: 2013

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. © 2013 Society for Sugar Research & Promotion.

Rocha G.J.M.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Martin C.,University of Matanzas | Martin C.,VTI Institute for Wood Technology and Wood Biology | da Silva V.F.N.,University of Sao Paulo | And 2 more authors.
Bioresource Technology | Year: 2012

Five pilot-scale steam explosion pretreatments of sugarcane bagasse followed by alkaline delignification were explored. The solubilised lignin was precipitated with 98% sulphuric acid. Most of the pentosan (82.6%), and the acetyl group fractions were solubilised during pretreatment, while 90.2% of cellulose and 87.0% lignin were recovered in the solid fraction. Approximately 91% of the lignin and 72.5% of the pentosans contained in the steam-exploded solids were solubilised by delignification, resulting in a pulp with almost 90% of cellulose. The acidification of the black liquors allowed recovery of 48.3% of the lignin contained in the raw material. Around 14% of lignin, 22% of cellulose and 26% of pentosans were lost during the process. In order to increase material recovery, major changes, such as introduction of efficient condensers and the reduction in the number of washing steps, should be done in the process setup. © 2012 Elsevier Ltd.

Martin C.,VTI Institute for Wood Technology and Wood Biology | Martin C.,University of Matanzas | Puls J.,VTI Institute for Wood Technology and Wood Biology | Schreiber A.,Sudan University of Science and Technology | Saake B.,Sudan University of Science and Technology
Holzforschung | Year: 2013

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 H2SO 4 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% H2SO 4, 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. © 2013 by Walter de Gruyter Berlin Boston 2013.

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