Solution-Based Deconstruction of (Ligno)-Cellulose (original) (raw)
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Changes of supramolecular cellulose structure
Abstract A newly identified cellulase with a high polysaccharide degrading potential and a processive mode of action, has been evaluated on cellulose fibers. Cellulase Cel9B from Paenibacillus barcinonensis is a modular endoglucanase with the domain structure GH9-CBM3c-Fn3-CBM3b, consisting of a family nine catalytic module GH9, an auxiliary module CBM3c, a fibronectin-like module Fn3, and a functional cellulose binding module CBM3b. The whole cellulase Cel9B (E1) and two truncated forms of the enzyme that consist of the catalytic module linked to the auxiliary module, GH9-CBM3c (E2), and of the cellulose binding module of the enzyme, CBM3b (CBD), were applied to softwood dissolving pulp. The changes in the supramolecular structure and morphology of the fibres after the enzymatic treatment were evaluated by viscosimetry, X-ray diffraction (XRD), thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy (SEM). XRD studies provided the crystallite size, interplanar distances and crystallinity index of the samples before and after the enzymatic treatment. The treatment with cellulases E1 and E2 decreased the degree of polymerization and increased the crystallinity index of the pulp. Both E1 and E2 had a pronounced capacity for removing fuzz and improved the smoothness and surface appearance of the fibers, as shown by SEM. On the other hand, CBD proved to be less effective under the tested conditions. Moreover, the solubility of dissolving pulp in alkaline solutions has been evaluated as an indirect measure of cellulose accessibility. A notable enhancement in alkaline solubility of the samples treated with the cellulases was observed.
Tailoring the Degree of Polymerization of Low Molecular Weight Cellulose
2011
The degradation of cellulose to lmw samples with DP w varying from 15 to 130 is investigated. Cellulose samples prepared from the hydrolysis of regenerated cellulose fibers in dilute HCl possess DP w ¼ 50. Applying homogenous degradation of microcrystalline cellulose in H 3 PO 4 at RT for 3 weeks, samples with DP w ¼ 35 and a PDI of 1.58 are obtained. Decreasing the hydrolysis temperature to 8 8C results in lmw cellulose with DP w > 70. Fractionation in DMA/LiCl provides samples with DP w ¼ 12 to 130, together with a narrow molecular weight distribution. Detailed structural analysis by 2D NMR spectroscopy reveals that the prepared lmw celluloses are suitable as mimics for cellulose.
Cellulose as a nanostructured polymer: A short review
Bioresources
Cellulose has a complex, multi-level supermolecular architecture. This natural polymer is built from superfine fibrils having diameters in the nano scale, and each such nanofibril contains ordered nanocrystallites and low-ordered nano-domains. In this review, the nano-structure of cellulose and its influence on various properties of the polymer is discussed. In particular, the ability of nano-scale crystallites to undergo lateral co-crystallization and aggregation, as well as to undergo phase transformation through dissolution, alkalization, and chemical modifica-tion of cellulose has been the subject of investigation. The recent investigations pave the way for development of highly reactive cellulosic materials. Methods for preparation nanofibrillated cellulose and free nano-particles are described. Some application areas of the nanostruc-tured and nano-cellulose are discussed.
Review Analyzing cellulose degree of polymerization and its relevancy to cellulosic ethanol
Biofuels Bioproducts Biorefining , 2011
The degree of polymerization (DP) of cellulose in cellulosic biomass and how it changes during enzymatic and chemical transformations has remained a fundamental property of interest to numerous researchers. Currently, with increased interest in cellulosic biofuels, more attention is being focused on determining changes in cellulose DP before and during pre-treatment, as well as the effect of DP on enzymatic deconstruction of cellulose to glucose. Different sources of celluloses from woody and non-woody biomass have been isolated and the DP has been frequently examined as a key parameter contributing to efficient biomass deconstruction. The isolation and derivatization/dissolution of cellulose are crucial steps in determining cellulose DP. This review summarizes approaches to measuring DP developed over the past six decades and highlights opportunities for further mprovements.
Peer-Reviewed Review Article Cellulose as a Nanostructured Polymer: A Short Review
Bioresources
Cellulose has a complex, multi-level supermolecular architecture. This natural polymer is built from superfine fibrils having diameters in the nano scale, and each such nanofibril contains ordered nanocrystallites and low-ordered nano-domains. In this review, the nano-structure of cellulose and its influence on various properties of the polymer is discussed. In particular, the ability of nano-scale crystallites to undergo lateral co-crystallization and aggregation, as well as to undergo phase transformation through dissolution, alkalization, and chemical modifica-tion of cellulose has been the subject of investigation. The recent investigations pave the way for development of highly reactive cellulosic materials. Methods for preparation nanofibrillated cellulose and free nano-particles are described. Some application areas of the nanostruc-tured and nano-cellulose are discussed.
An Update on Overview of Cellulose, Its Structure and Applications
Cellulose (C 6 H 10 O 5) n is one of the most ubiquitous organic polymers on the planet. It is a significant structural component of the primary cell wall of green plants, various forms of algae and oomycetes. It is a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1 → 4) linked d-glucose units. There are various extraction procedures for cellulose developed by using different processes like oxidation, etherification and esterification which convert the prepared celluloses in to cellulose derivatives. Since it is a non-toxic, biodegradable polymer with high tensile and compressive strength, it has widespread use in various fields such as nanotechnology, pharmaceutical industry, food industry, cosmetics, textile and paper industry, drug-delivery systems in treating cancer and other diseases. Micro-crystalline cellulose in particular is among the most frequently used cellulose derivatives in the food, cosmetics, pharma industry, etc. and is an important excipient due to its binding and tableting properties, characterized by its plasticity and cohesiveness when wet. Bacterial cellulose's high dispensability, tasteless and odourless nature provides it with lot of industrial applications. Currently, about half of the waste produced in India contains about 50% cellulose which can be used productively. This chapter deals with the chemistry of cellulose, its extraction and its properties which help various industries to make the most of it.
2020
Among the natural organic polymers, cellulose is the most abundant member, which exists as cell wall components of a main plant. It carries immense importance because it is a biodegradable organic resource which is renewable. Due to these, studies on cellulose have been on for over 20 decades, but there is still need for further research to fully elucidate its chemical synthesis, biosynthesis, regiospecific substitution reactions, crystal structure, interrelationships between the structure and function of its derivatives, etc. Specifically, synthesis of cellulose is highly important, but also a severely difficult problem to solve. Enzymatic synthesis of cellulose with the help of cellulase came as a welcome development, however the approach seems not to meet the modern molecular design of function-specific cellulose derivatives. This is because it does not support regiospecific introduction of functional groups into the hydroxyl group of interest in the repeating cellulose pyranose units. The available functional cellulose derivatives include cellulose esters and liquid crystalline ethers, ethers with chiral recognition features, sulfated anticoagulant cellulose, antitumor branched cellulose, etc. [1]. Despite all these, certain areas still remain unclear, such as structure-property relationship, the most actively functional derivatives with respect to the substituted positions (2, 3-or 6-). For molecular design of advanced cellulose based materials, it is pertinent to use an approach which gives room for preparation of cellulose derivatives such that functional groups can be easily incorporated into either of the 2,3,6-hydroxyl groups of the repeating cellulose pyranose units. Cellulose occupies a large percentage (35-50%) of lignocellulosic materials and it has been identified as a potential renewable source of bio-based chemicals and biofuels. Several important industrial fuels and chemicals, such as ketones, carboxylic acids, hydrocarbons, and ethanol can be obtained from the hydrolysis of cellulose followed by fermentation of saccharides [2, 3]. It has been noted however that production of chemical from cellulose is sometimes not cost effective compared to those obtained from petrochemicals and they are sometimes even more expensive than those obtained from other renewable sources, such as starch. This is as a result of the relatively