The work described in this dissertation focused on chemistry related to the use of aqueous sodium hydroxide as a treatment in the processing of wheat straw. A major emphasis was the comprehensive evaluation of straw component partitioning due to sodium hydroxide (NaOH) processing. This was evaluated over a range of NaOH concentrations (0­‐10%, w/v), all at 50°C, 5 h treatment period, and 3% solid loading. Solid and liquid phases resulting from NaOH treatments were evaluated. Total solids recovered in the NaOH­‐treated solid phase ranged from 47.4­‐88.0%. Overall carbohydrate recovery in the combined solid and liquid phases was negatively correlated with the alkali concentration of the treatment liquor. The glucan content of the NaOH‐treated solid phase ranged from 37.2­‐67.4%. Glucan recovery in the solid phase was relatively high in all cases, the minimum value being ~98%. Increasing amounts of xylan partitioned into the liquid phase as sodium hydroxide concentrations increased – it ranged from 31­‐83% of the xylan being recovered in the soluble phase. Carbohydrate analyses of the pretreated liquor revealed that the majority of carbohydrate loss from the solid fraction could be recovered in the liquid phase in form of oligomers and monomers due to alkaline degradation. The interconversion of glucose, fructose, and mannose under the alkaline condition played an important role in the presence of those sugars. Increase in NaOH concentration contributed to increase in amount of cellulose­‐derived and hemicellulose‐derived oligomers in the pretreated liquor. All oligomers except fructooligomers in NaOH pretreated liquor were higher than those found in water extraction at 50°C, 5 h. Total carbohydrate recovery from the solid and liquid fractions was as high as 99% for glucose and glucan in 5% NaOH treatment and 80‐95% for xylose and xylan in 1-­10% NaOH treatment. The presence of NaOH as extraction reagent dramatically induced lignin and ash removal from the pretreated solid with up to 63% acid insoluble lignin (AIL) and 87% ash extraction. Solid fractions resulting from NaOH pretreatments (up to 5% NaOH) were tested for their susceptibility to enzymatic saccharification using cellulase and cellulase/xylanase enzyme preparations. The cellulase/xylanase enzyme preparation was found to be more effective at cellulose saccharification than the cellulase enzyme preparation alone. Maximum glucose yield, which corresponded to the 5% NaOH treatment, was 82% over the standard 48 h saccharification period. Extended saccharifications times to 120 h showed that the conversion yield approached 90%. Sequential treatments of the straw (i.e. initial alkali treatment – first enzyme saccharification – second alkali treatment ‐ second enzyme treatment) revealed the NaOH treatment has the potential to render essentially all (~99%) of the straw glucan susceptible to enzyme saccharification. This suggests that the layered molecular arrangement of cellulose, hemicellulose, and lignin in the cell wall impacts biomass recalcitrance and glucan conversion yield. The other major focus of this dissertation research was the characterization of alkali neutralization, which occurs during the aqueous alkali processing of wheat straw. The approach taken was to evaluate the time course of alkali uptake and to determine the underlying nature of alkali uptake. The knowledge generated from this study is useful for understanding the nature of the alkali‐induced chemistry that is at the heart of alkali processing of agricultural byproducts, foods, and forest products. Alkali uptake/acid generation measurements were monitored for wheat straw suspensions at pH 11 and 30°C. The first phase of alkali uptake corresponded to the 30‐second time period over which the pH of the wheat straw suspension was adjusted from its original pH (~6.6) to pH 11. Alkali neutralization during this period was attributed to the instantaneous ionization of solvent accessible Bronstad acids. Following pH adjustment to 11.0, the time course of subsequent alkali uptake was recorded. The time course appeared biphasic. The early phase, which corresponded to the relatively rapid uptake of alkali, was evident during the first 24 hours. The later phase, which was characterized by the relatively slow uptake of alkali, was maintained for the length of the study (up to 96 hours). Alkali uptake during the early phase of the time course appears to be determined by the rate of hydrolysis of readily accessible esters – primarily acetic acid esters (acetyl groups). Alkali uptake during the later phase of the time course appears to be impacted by the rate of alkali penetration into the straw and the rate of production of alkali‐induced acid degradation products. The uptake of alkali in the pH adjustment phase was ~ 120 μEq per gram wheat straw, the uptake of alkali in the early phase of time course was ~ 1,064 μEq per gram wheat straw, and the rate of uptake in the later phase of the time course 6.10 μEq per gram wheat straw per hour. Amount of acetyl groups, ferulic acid, and p-­coumaric acid generated during 96-­h pretreatment revealed that they are major esters being hydrolyzed under the studied condition. Combined, these ester-­derived acids contributed up to ~ 28% of overall alkali uptake. In addition, alkaline degradation products quantified in this study showed additional ~ 28% contribution to the overall alkali uptake. / Graduation date: 2012

Submitted by Felipe Lange Shimizu null (felipe_lash@hotmail.com) on 2018-04-04T17:40:35Z No. of bitstreams: 1 Versão Final.pdf: 2417638 bytes, checksum: cbd92ea0f55b939141e8dbb758da327f (MD5) / Rejected by Adriana Aparecida Puerta null (dripuerta@rc.unesp.br), reason: Prezado Felipe Lange Shimizu, Solicitamos que realize uma nova submissão seguindo as orientações abaixo: - Capa - Faltou a capa no documento enviado. Este item é elemento obrigatório de acordo com as normas de trabalhos do seu Programa de Pós Graduação. Agradecemos a compreensão e aguardamos o envio do novo arquivo. Atenciosamente, Biblioteca Campus Rio Claro Repositório Institucional UNESP on 2018-04-05T13:45:30Z (GMT) / Submitted by Felipe Lange Shimizu null (felipe_lash@hotmail.com) on 2018-04-05T13:57:48Z No. of bitstreams: 1 Dissertação Final Biblioteca.pdf: 2476461 bytes, checksum: 98bb493283b6d060e268893b026507a0 (MD5) / Approved for entry into archive by Adriana Aparecida Puerta null (dripuerta@rc.unesp.br) on 2018-04-05T17:46:11Z (GMT) No. of bitstreams: 1 shimizu_fl_me_rcla.pdf: 2148045 bytes, checksum: 5ae73bad5319cc903eba26a7980c267c (MD5) / Made available in DSpace on 2018-04-05T17:46:11Z (GMT). No. of bitstreams: 1 shimizu_fl_me_rcla.pdf: 2148045 bytes, checksum: 5ae73bad5319cc903eba26a7980c267c (MD5) Previous issue date: 2018-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A biomassa lignocelulósica, como a proveniente da cana-de-açúcar, é uma fonte abundante de resíduo que pode ser usado como matéria-prima na produção de energia. Para melhor aproveitar essa biomassa, moagem e pré-tratamentos podem ser usados para alterar a estrutura do material lignocelulósico, remover lignina e hemicelulose, expondo a celulose e assim aumentando sua acessibilidade. A acessibilidade à celulose tem sido indicada como uma das propriedades mais importantes para uma boa digestibilidade enzimática. Entretanto, as biomassas geradas da cana-de-açúcar possuem características físico-químicas diferentes, respondendo de modo diferente aos pré-tratamentos. Neste contexto, este estudo teve como objetivo verificar os efeitos da remoção de lignina e hemicelulose das biomassas da cana-de-açúcar (fração externa, entrenó, nó e folha) na acessibilidade à celulose. A cana-de-açúcar foi fracionada em fração externa, nó, entrenó e folha. Cada fração passou pelos pré-tratamentos ácido (5, 10, 20 %, m/m massa de ácido por massa de material, a 121°C/30 min), alcalino (5, 10, 20 e 30 % NaOH m/m) e oxidativo (0,5, 1, 2 e 3 horas com clorito de sódio 30 %). As amostras foram caracterizadas quanto ao seu conteúdo de celulose, hemicelulose e lignina. A determinação de acessibilidade foi realizada com corantes Direct, Orange (superfície específica externa), Direct Blue (superfície específica interna) e Vermelho Congo (superfície total). A hidrólise enzimática (15 FPU/g de material, Cellic Ctec 2 - Novozymes) foi realizada para avaliar o efeito dos pré-tratamentos e acessibilidade à celulose no rendimento em glicose. O efeito dos pré-tratamentos foi primeiramente analisado pela quantidade de massa recuperada. Todas as frações estudadas apresentaram uma tendência em perder massa com aumento da concentração de reagente utilizado no pré-tratamento. O pré-tratamento ácido resultou em menor recuperação de massa, o que ocorreu em função da solubilização de hemicelulose. A caracterização química apontou a remoção de hemicelulose e principalmente lignina dos materiais em função do pré-tratamento e das suas condições. A deslignificação com clorito de sódio (oxidativo) resultou em remoção de lignina, chegando a quase a sua totalidade em materiais como a folha. A determinação de acessibilidade com os corantes Vermelho Congo, Direct Blue e Direct Orange indicaram que o aumento da concentração de reagentes no pré-tratamento provoca aumento de acessibilidade à celulose. Entretanto, os corantes Direct Orange e Blue foram mais precisos na determinação da acessibilidade à celulose em comparação ao Vermelho Congo. A fração de menor recalcitrância, entrenó, apresentou adsorção de 525,9 mg/g no ensaio com Vermelho congo, o Direct Orange 1333,3 mg/g e o Direct Blue 746,3 mg/g. O rendimento em glicose na hidrólise enzimática seguiu a tendência de melhora com aumento da acessibilidade. Do mesmo modo, a remoção de lignina resultou em maior rendimento em glicose na hidrólise enzimática, o entrenó deslignificado resultou na quase completa conversão da celulose em glicose. Este estudo identificou a fração externa como mais recalcitrante, e entrenó como menos recalcitrante, resultando em menor rendimento e maior de glicose na hidrólise enzimática, respectivamente. A remoção de hemicelulose e lignina por meio de pré-tratamentos influenciou diretamente na acessibilidade à celulose, resultando em melhor ação das enzimas na hidrólise enzimática de todas as frações. / The lignocellulosic biomass, such as the provided by the sugarcane, is an abundant source of raw materials for energy production. In order to better use this biomass, milling and pretreatments can be employed to alter the structure of the materials, remove lignin and hemicellulose. This effect exposes the cellulose and raises its accessibility, which is is one of the most important property to ensure enzymatic digestibility. However, the biomass generated from the sugarcane have different physicochemical characteristics, giving different responses to the pretreatments. In this context, this study aimed to verify the effects of lignin and hemicellulose removal from the sugarcane biomass (external fraction, node, internode and leaf) on cellulose accessibility. The sugarcane was fractioned in external fraction, node, internode and leaf. Each fraction was pretreated with acid (5, 10, 20 % m/m acid mass per material mass, at 121°C/30 min), alkaline (5, 10, 20, 30 % NaOH m/m) oxidative (0,5, 1, 2 ,3 h charged with 30 % sodium chlorite). The chemical composition of the samples was determined based on cellulose, hemicellulose and lignin contents. Accessibility was determined by dye adsorption of Direct Orange (external specific surface), Direct Blue (internal specific surface) and Congo Red (total surface). Enzymatic hydrolysis (15 FPU/g of biomass, Cellic Ctec 2 – Novozymes) was used to verify the effects of pretreatments and cellulose accessibility on the glucose yield. All studied fractions showed tendency to lose mass with increasing reagent concentrations used in the pretreatments. Acid pretreatment resulted in low mass recovery due to hemicellulose solubilization. Chemical composition showed hemicellulose removal and significant lignin removal from the materials due to the pretreatments and their conditions. Delignification by sodium chlorite (oxidative) resulted in lignin removal, with almost completely removal with leaf samples. Accessibility determined by Congo Red, Direct Orange and Direct Blue dyes indicated that more aggressive pretreatments improved cellulose accessibility. However, Direct Orange and Direct Blue dyes were more precise than Congo Red while evaluating cellulose accessibility. The less recalcitrant fraction, the internode, showed 525,9 mg/g of Congo Red adsorption, 1333,3 mg/g of Direct Orange and 746,3 mg/g of Direct Blue. Glucose yield during enzymatic hydrolysis improved with higher cellulose accessibility. Lignin removal resulted in higher glucose yield, with delignified internode samples showing almost complete cellulose conversion. This study identified the external fraction as the most recalcitrant and the internode as the least recalcitrant, resulting in lower glucose yield and higher glucose yield, respectively. Hemicellulose and lignin removal by the pretreatments directly influenced cellulose accessibility, resulting in better enzymatic activity across all fractions.