Homogenous reactions of cellulose from different natural sources (original) (raw)
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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.
Plant and Bacterial Cellulose: Production, Chemical Structure, Derivatives and Applications
Orbital: The Electronic Journal of Chemistry, 2019
Cellulose is one of the most abundant biopolymers in nature. It is used in the industry in various ways, in both its original and modified forms and the latter are called cellulose derivatives. These derivatives are used in several industrial such as the pharmaceutical, food, cosmetics and can be used in solid or semi-solid form. An important application that has been currently clarified is the use of some types of cellulose derivatives as adsorbents for both metal ions and other molecules. An example is the decontamination of wastewater, as with the industrial development, some water sources are compromised and decontamination by conventional means is often not enough, hence the need for new techniques. The main advantage of using natural polymers is that they are biodegradable, because it is extremely important that a product disappear after fulfilling its purpose. An example of a natural polymer is cellulose synthesized by bacteria, also known as bacterial cellulose (BC). It has been the subject of several studies in the last decade, mainly due to the fact that it is a highly pure polymer, which makes their physical and chemical properties very different from those of plant cellulose, and also because it is easy to produce, with yields varying from one bacterium to another. The aim of this paper was to gather general information about the structures, production mode, synthesis and industrial applications of bacterial, vegetable and cellulose derivatives.
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
Chemical Functionalization of Cellulose Derived from Nonconventional Sources
Cellulose Fibers: Bio-And Nano- …, 2011
Chemical functionalization of cellulose aims to adjust the properties of macromolecule for different purposes, particularly, as a chemical feedstock for production of cellulose derivatives for a variety of applications. The conventional sources of cellulose include cotton linters and wood pulp which now-a-days are discouraged on account of the cost of the former and environment conservative regulations associated with the latter. Further, renewable raw materials are gaining considerable importance because of the limited existing quantities of fossil supplies. In this regard, cellulose-rich biomass derived from the nonconventional sources such as weeds, fibers, bamboos, and wastes from agriculture and forests, etc. acquires enormous significance, as alternative chemical feedstock, since it consists of cellulose, hemicellulose, and lignin, which contain many functional groups suitable to chemical functionalization. Etherification of cellulose through methylation, carboxymethylation, cynaoethylation, hydroxypropylation, single or mixed, is one of the most important routes of cellulose functionalization. Chemical composition and rheological characteristics make possible the selection of the modified cellulose to serve special applications. Prompted by above facts, possibility for chemical functionalization of cellulose rich biomass derived from bamboo, Dendrocalamus strictus (DCS), and noxious weeds-Lantana camara (LC) and Parthenium hysterophorus (PH) for their utilization was examined and results are reported. Proximate analysis of these materials was conducted and processes were standardized for production of a-cellulose on 1 kg batch scale. The percent yield, Av. DP, and the percentage of a-cellulose content of the obtained celluloses were found in the range of 35-40, 400-825, >90 (Brightness 80% ISO), respectively. Processes were optimized for production of water-soluble carboxymethyl cellulose (DCS, LC, and PH), cyanoethyl cellulose (DCS) and water-soluble hydroxypropyl cellulose (DCS and PH). The optimized products were characterized by IR spectra. Rheological studies of 1% and 2% aqueous solutions of the optimized carboxymethyl celluloses and hydroxypropyl celluloses showed their non-Newtonian
Catalyst-free conversion of alkali cellulose to fine carboxymethyl cellulose at mild conditions
World Applied Sciences …, 2009
Cellulose fibers were converted into a valuable cellulose derivative, which is easily marketable with additional values. Alkali cellulose and carboxymethyl cellulose (CMC) is the most important cellulose derivatives. Alpha-cellulose was furnished as raw material for production of CMC, which is obtained from short cotton fibers, then purified. Alpha-cellulose is available in the international market. Preparation of carboxymethyl cellulose was conducted using sodium hydroxide solution in sequential reactions with monochloroacetate (MCA) at desired condition. Alkali cellulose has been successfully synthesized in a batch reactor with degree of substitution (DS) of 0.15 to 0.7 and excellent purity of 99.3% at pH 7. The maximum degree of substitution of 0.7 was defined with 40% MCA and 30% NaOH. The reaction temperature was controlled and the purity of the product was examined through the course of reactions. The samples of CMC were examined by scanning electron microscope and FTIR techniques. A comparison study with CMC available in the international market has been conducted. The obtained results for the synthesized CMC with more than 99% purity were promising. The synthesized CMC was easily dissolved in water. The obtained product is absolutely recommended for pharmaceutical applications and as food additives.
Cellulosic materials: Structure and enzymatic hydrolysis relationships
Journal of Applied Polymer Science, 1984
Structural and morphological features of four different cellulosic materials have been deeped by X-ray, CP-MAS NMR, water retention, and specific surface area analysis. Hydrolysis time courses of two of these celluloses were followed by employing a n enzymatic system consisting of a cellulase from Trich&nna viride and a cellobiase from Aspergillw niger. Experimental results were rationalized on the basis of a mathematical model previously verified on the other two substrates. All the celluloses presented the same mechanistic framework involving product inhibitions. The most efficient pretreatment was found to be the dissolution of cellulosic material in the dimethyl sulfoxide-paraformaldehyde system and regeneration with ammonia. This treatment cancelled the memory of the initial structural order.
Structural Changes and Reactivity of Cellulose after Alkaline Treatment
In this paper, structural characteristics and reactivity of initial and alkali-treated cellulose samples have been studied. Such characteristics of the samples as degree of crystallinity (X), type and content of crystalline modifications (KM), lateral size of crystallites (Lcr), degree of polymerization (DP), specific surface area (S) were obtained. It was found that high area of specific surface combined with low size of crystallites promote to a high reactivity of cellulose in production of viscose. On the other hand, high DP and presence of CII allomorph decrease reactivity of cellulose.
Bacterial Cellulose: Biosynthesis and Applications
IntechOpen eBooks, 2023
Bacterial cellulose (BC) or microbial cellulose (MC) was considered a bioactive material characterized by high absorbed water, high crystalline, high tensile strength, and biodegradability. However, bacterial cellulose has wide applications, such as biomedical, textile, paper industries, food, drug release, and cosmetic applications. So the microbial cellulose production from Acetobacter xylinum from different wastes such as carbon and nitrogen sources, for example, pineapple peel juice, sugar cane juice, dry olive mill residue, waste beer yeast, and wheat thin stillage, are characterized by FTIR, XRD, SEM, and TEM. The product yield of bacterial cellulose is affected by different factors such as the concentration of sugar in carbon source, temperature and time of incubator of the strain, and pH of media. So, it must be studied with the enzymatic pathway procedure.
A Review on the Modification of Cellulose and Its Applications
Polymers
The latest advancements in cellulose and its derivatives are the subject of this study. We summarize the characteristics, modifications, applications, and properties of cellulose. Here, we discuss new breakthroughs in modified cellulose that allow for enhanced control. In addition to standard approaches, improvements in different techniques employed for cellulose and its derivatives are the subject of this review. The various strategies for synthetic polymers are also discussed. The recent advancements in polymer production allow for more precise control, and make it possible to make functional celluloses with better physical qualities. For sustainability and environmental preservation, the development of cellulose green processing is the most abundant renewable substance in nature. The discovery of cellulose disintegration opens up new possibilities for sustainable techniques. Based on the review of recent scientific literature, we believe that additional chemical units of cellulos...