Papers by Viviane Nascimento
Industrial Crops and Products, 2014
Waste and Biomass Valorization, 2014
This work aims to evaluate the recovery of soluble lignin from an effluent produced in the alkali... more This work aims to evaluate the recovery of soluble lignin from an effluent produced in the alkaline delignification of sugarcane bagasse. The lignin polymerization was carried out using different substract-enzyme relation, namely 0.05 and 1.8 mg soluble lignin for peroxidase activity, and different H 2 O 2 concentration, namely 0.18 and 2.1 mol of H 2 O 2 per peroxidase unit, furthermore was achieved using horseradish peroxidase and a preliminary study using laccase produced by Trametes versicolor. The highest lignin polymerization yield was 93 % for 50 Lg lignin/unit of peroxidase activity and 0.2 Lmol of H 2 O 2 /unit of peroxidase activity. The polymerization process occurred after a considerable increase in the molecular weight of lignin (from 415 Da in the effluent to 2,122 Da in the polymer obtained after 30 min of reaction) as demonstrated by gel permeation chromatography. The average molecular weight of the obtained polymer changed as a function of reaction time, which of 0, 0.5, 4.0, 8.0, 16.0 and 42.0 h produced lignin polymers with 415, 2,122, 1,576, 1,150, 794 and 4,595 Da, respectively. The preliminary treatment study of the effluent with a culture broth of T. versicolor with laccase increased the average molecular weight of soluble lignin from 415 to 1,150 Da, however the polymerization catalyzed by laccase was not accomplished by the effective lignin polymerization followed by an efficient separation.
Biofuels in Brazil, 2014
Sugarcane juice-derived ethanol (1G ethanol) has been the major renewable energy source in Brazil... more Sugarcane juice-derived ethanol (1G ethanol) has been the major renewable energy source in Brazil after the inception of National Alcohol Program in 1970. The remaining part, after the processing of sugarcane and extraction of juice (sugarcane bagasse-SB and straw-SS), are the promising sugar feedstock for cellulosic ethanol (2G ethanol) due to their abundant availability round the year and high energy content. However, sugar recovery from lignocellulosic biomass is not easy and needs intensive processing. Pretreatment to overcome the recalcitrance of these feedstocks and sugar recovery constitute almost 30 % cost of 2G ethanol production. Several pretreatment methods have been studied recently aiming to either lignin removal or hemicellulose from SB/SS for the subsequent enzymatic hydrolysis for fermentable sugar production. However, steam explosion and dilute sulfuric acid have been emerged out as two successful options for the pretreatment of SB/SS. Pilot level studies at our institute (Laboratório Nacional de Ciência e Tecnologia do Bioetanol-CTBE, Campinas, Brazil), for the pretreatment of SB/SS considering steam explosion and dilute acid pretreatment, have shown the promising results. Both the pretreatment strategies are scalable and reproducible at the commercial level. This chapter deals with the experiments made on SB/SS for the steam explosion and dilute acid hydrolysis and the sugar recovery after enzymatic hydrolysis. Furthermore, process configurations for saccharification of pretreated biomass and the conversion of released sugars into ethanol have also been discussed.
Industrial Crops and Products, 2015
Brazil, with 185 million tons of solid residues generation per harvest, is the largest producer o... more 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.
Industrial Crops and Products, 2014
This work evaluated the conversion of sugarcane straw into a glucose-rich hydrolysate using a com... more This work evaluated the conversion of sugarcane straw into a glucose-rich hydrolysate using a combined process system (CPS) which consists of pretreatment, delignification and enzymatic hydrolysis. The sugarcane straw, with 38.1%, 29.2% and 24.2% of cellulose, hemicellulose and lignin respectively, was submitted to a hydrothermal pretreatment and a delignification process in order to increase the cellulose enzymatic hydrolysis. Straw is the residue to be obtained in sugarcane mills without burning the land previously to the harvesting The CPS, with pretreatment at 190 • C, 10 min, showed 95% of hemicellulose solubilization, 78% of lignin removal and 29% of cellulose degradation. The enzymatic hydrolysis of CPS-cellulignins achieved over 60% cellulose conversion. Considering the cellulose content present in the raw sugarcane straw, only 50% was converted into glucose, due to degradation during the CPS and the enzymatic inefficiency in the hydrolysis stage. In addition, the delignification step did not improve the overall cellulose conversion of the sugarcane straw.
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Papers by Viviane Nascimento