A bright future for cellulose

Schurz, J.

doi:10.1016/s0079-6700(99)00011-8

Cited by 161 publications

(56 citation statements)

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“…Cellulose is a linear homopolymer consisting of b-(1-4)-linked anhydroglucopyranose units (AGU). The wood is the main source of cellulose and it is considered a slowly regenerated raw material, because of the time required for a tree may be cut to produce cellulose [4] . In contrast, cellulose from other raw materials, such as cotton, has become attractive as a source for cellulose derivatives, because it is available in large quantities, and is routinely cultivated around the world.…”

Section: Introductionmentioning

confidence: 99%

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Morgado

Frollini

2011

Polímeros

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Abstract:Cellulose acetates with different degrees of substitution (DS, from 0.6 to 1.9) were prepared from previously mercerized linter cellulose, in a homogeneous medium, using N,N-dimethylacetamide/lithium chloride as a solvent system. The influence of different degrees of substitution on the properties of cellulose acetates was investigated using thermogravimetric analyses (TGA). Quantitative methods were applied to the thermogravimetric curves in order to determine the apparent activation energy (Ea) related to the thermal decomposition of untreated and mercerized celluloses and cellulose acetates. Ea values were calculated using Broido's method and considering dynamic conditions. Ea values of 158 and 187 kJ mol -1 were obtained for untreated and mercerized cellulose, respectively. A previous study showed that C6OH is the most reactive site for acetylation, probably due to the steric hindrance of C2 and C3. The C6OH takes part in the first step of cellulose decomposition, leading to the formation of levoglucosan and, when it is changed to C6OCOCH 3 , the results indicate that the mechanism of thermal decomposition changes to one with a lower Ea. A linear correlation between Ea and the DS of the acetates prepared in the present work was identified. Keywords: Linter cellulose, cellulose acetates, thermal decomposition. Decomposição Térmica de Celulose de Linter Mercerizado e seus Acetatos Obtidos a partir de Reação HomogêneaResumo: Acetatos de celulose com graus de substituição, GS, variando entre 0,6 e 1,9, foram preparados previamente a partir de celulose de linter mercerizado, em meio homogêneo, usando N,N-dimetilacetamida/cloreto de lítio como sistema de solvente. A influência de diferentes graus de substituição nas propriedades dos acetatos de celulose foi investigada usando a análise termogravimétrica (TGA). Métodos quantitativos foram aplicados nas curvas termogravimétricas obtidas a fim de determinar a energia de ativação aparente (Ea) relacionado à decomposição térmica de celulose não-tratada e mercerizada e acetatos de celulose. Valores de Ea foram calculados usando o método de Broido e considerando condições dinâmicas. Valores de Ea de 158 e 187 kJ mol -1 foram obtidos para a celulose não-tratada e mercerizada, respectivamente. Em trabalho anterior verificou-se que o C6OH é o sítio mais reativo na acetilação, provavelmente devido ao impedimento estérico de C2 e C3. O C6OH participa da primeira etapa de decomposição da celulose, levando à formação de levoglucosana e, quando se tem a substituição para C6OCOCH 3 , o resultado indica que o mecanismo de decomposição térmica muda para um com Ea menor. Uma correlação linear entre Ea e o GS dos acetatos preparados no presente trabalho foi identificada. Palavras-chave: Celulose de linter, acetatos de celulose, decomposição térmica.

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Section: Introductionmentioning

confidence: 99%

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Morgado

Frollini

2011

Polímeros

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“…Cellulose is one of the most abundant natural polymers and could be a primary chemical resource in the future for its renewability, biodegradability, biocompatiblity and derivatization ability [4]. However, cellulose is difficult to process in normal aqueous solution or in the melted state on account of its strong intermolecular and intramolecular hydrogen bonds.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Flocculation Behavior of Cationic Cellulose Prepared in a NaOH/Urea Aqueous Solution

Yan¹,

Tao

Bangal

2009

CLEAN Soil Air Water

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Water soluble cationic cellulose was synthesized by the reaction between microcrystalline cellulose and 2,3-epoxypropyltrimethylammonium chloride in a NaOH/urea aqueous solution. The characterization of the cationic cellulose was performed by NMR spectroscopy, elemental analysis, thermogravimetric analysis, and viscosity analysis. The effects of reaction time and molar ratio of the reagents on the structure of the products were also investigated, and it was found that the degree of substitution (DS) of the cationic cellulose obtained depended on both the ratio of the 2,3-epoxypropyltrimethylammonium chloride to cellulose and the reaction time. The flocculation capacity of the cationic cellulose was determined with 0.25 wt % kaolin suspension using the standard jar test. Encouraging results were found and cationic cellulose may be applicable for use as a novel flocculant in wastewater treatment.

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“…Cellulose is the most abundant renewable, biodegradable, and biocompatible polymer resource in nature and one of the main chemical resources of the future (Schurz 1999). It can be enzymatically hydrolyzed and then fermented to ethanol, or digested by bacteria to biogas.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of ethanol and biogas production from high‐crystalline cellulose by different modes of NMO pretreatment

Jeihanipour

Karimi

2009

Biotech & Bioengineering

111

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Pretreatment of high-crystalline cellulose with N-methyl-morpholine-N-oxide (NMO or NMMO) to improve bioethanol and biogas production was investigated. The pretreatments were performed at 90 and 120 degrees C for 0.5-15 h in three different modes, including dissolution (85% NMO), ballooning (79% NMO), and swelling (73% NMO). The pretreated materials were then enzymatically hydrolyzed and fermented to ethanol or anaerobically digested to biogas (methane). The pretreatment at 85% NMO, 120 degrees C and 2.5 h resulted in 100% yield in the subsequent enzymatic hydrolysis and around 150% improvement in the yield of ethanol compared to the untreated and water-treated material. However, the best results of biogas production were obtained when the cellulose was treated with swelling and ballooning mode, which gave almost complete digestion in 15 days. Thus, the pretreatment resulted in 460 g ethanol or 415 L methane from each kg of cellulose. Analysis of the structure of treated and untreated celluloses showed that the dissolution mode can efficiently convert the crystalline cellulose I to cellulose II. However, it decreases the water swelling capacity of the cellulose. On the other hand, swelling and ballooning modes in NMO treatment were less efficient in both water swelling capacity and cellulose crystallinity. No cellulose loss, ambient pressure, relatively moderate conditions, and high efficiency make the NMO a good alternative for pretreatment of high-crystalline cellulosic materials.

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A bright future for cellulose

Cited by 161 publications

References 0 publications

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Synthesis and Flocculation Behavior of Cationic Cellulose Prepared in a NaOH/Urea Aqueous Solution

Enhancement of ethanol and biogas production from high‐crystalline cellulose by different modes of NMO pretreatment

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