First Foreword Wertz, Jean-Luc; Mercier, Jean P.; Bédué, Olivier
Cellulose Science and Technology
Book Chapter
It is a common statement to say that cellulose is the world’s most abundant
polymer. In view of its importance to mankind, an enormous research effort,
substantiated by myriads of reports and ...patents, has been devoted to this
biopolymer in the last 150 years. The periodical appearance of textbooks
presenting in perspective the major developments of the science of cellulose is
therefore crucial for those who want to stay abreast, without being submerged
by the overwhelming primary literature.
Cellulose Derivatives Wertz, Jean-Luc; Mercier, Jean P.; Bédué, Olivier
Cellulose Science and Technology
Book Chapter
Highly purified wood pulp composed of 92-98 % cellulose, known as dissolving
pulp, is utilized for manufacturing cellulosic products derived from the chemical
processing of cellulose. With an annual ...global production averaging 3.65 million
tonnes in 2003, dissolving pulp accounted for 2.8 % of the total wood pulp
production. 1, 2 In 1998, pure cellulosic products (predominantly viscose)
represented about 60 % of the uses for dissolving pulp, and derivatives of cellulose about 40 %. 2Chemical modifications of cellulose generally involve reaction with its 2, 3 and
6 hydroxyl groups. 3 These reactive groups undergo most of the reactions
characteristic of alcohols. Esterification and etherification of cellulose are of
particular importance.
Despite its chemical stability, cellulose can be degraded non-enzymatically by
acids, alkalis, oxidants, thermal energy, mechanical means and radiations.Like cellulases, acids catalyze the hydrolysis ...of the glycosidic linkages in cellulose.
Acid hydrolysis of cellulose leads to high yields of glucose under certain conditions. 1 There are two acid hydrolysis processes commonly used for converting
cellulosic biomass to ethanol: dilute acid hydrolysis and concentrated acid
hydrolysis. 2, 3 Both technologies have long industrial histories. 4Alkalis also cause degradation of cellulose but with a completely different mode
of action. Alkaline degradation occurs in two primary ways: endwise degradation (peeling) and alkaline hydrolysis of glycosidic bonds.
Fuels and Chemicals from Biomass Wertz, Jean-Luc; Mercier, Jean P.; Bédué, Olivier
Cellulose Science and Technology
Book Chapter
Cellulose is the most abundant biopolymer on Earth with an estimated annual
production of ~7.5 × 1010 tonnes through photosynthesis. 1, 2, It is also the
most common form of carbon in plant biomass, ...defined as any plant-derived
organic material excluding material embedded in geological formation and/or
fossilized. Biomass is a renewable resource. Plants use sunlight to convert water
and carbon dioxide into carbohydrates that are stored as chemical energy,
through a process called photosynthesis. The composition of biomass depends
upon the plant species:Some plants, such as sugar cane and sugar beet, store the chemical energy
as simple sugars (mono-and disaccharides). They are mostly used for food.
Introduction Wertz, Jean-Luc; Mercier, Jean P.; Bédué, Olivier
Cellulose Science and Technology
Book Chapter
As early as in 1838, Anselme Payen 1 established that the fibrous component
of all higher plant cells had a unique chemical structure, which he named
cellulose. 2 Cellulose is the main molecule in ...cell walls of higher plants.
Cellulose is also produced by some algae, bacteria, fungi, protozoans, and
animal tunicates. There is more cellulose in the biosphere than any other
substance. The macromolecular nature of cellulose was demonstrated in
about 1930. Then it was established that cellulose is a polymer of glucose
units. The chemical composition and conformation of cellulose chains combined with their hydrogen bonding system are responsible for their tendency
to form crystalline aggregates.
Preface Wertz, Jean-Luc; Mercier, Jean P.; Bédué, Olivier
Cellulose Science and Technology
Book Chapter
Found in the walls of all plant cells, cellulose crystals are organized in nanoscalar microfibrils embedded in a complex matrix. Thus, in addition to its
potential as a raw material for the ...production of biofuels, these cellulose nanofibers, with an elasticity modulus close to that of carbon fibers, also offer great
potential in the production of new composite materials.
Cellulose is a chemically stable polymer. Its glycosidic bonds are strong and
stable under various reaction conditions. However, cellulose can be degraded in
Nature by enzymes as an essential part of ...the carbon cycle, and non-biologically
by acids, alkalis, oxidants, mechanical means, thermal energy and radiations.
1, 2In a typical cellulose-degrading ecosystem, a variety of cellulolytic bacteria and
fungi work in association with related microorganisms to convert insoluble
cellulose to soluble sugars, primarily cellobiose and glucose, which are then
assimilated by the cell. 1 For catalyzing this process, the cellulolytic microbes
produce a wide diversity of enzymes, known as cellulases. Cellulases catalyze the
hydrolysis of the b-1,4-glucosidic linkages in cellulose. They are members of the
glycoside hydrolase (GH) families of enzymes that hydrolyze the polysaccharides
in plant cell walls. 2 Due to the structural complexity and rigidity of cellulosicsubstrates, their efficient degradation generally requires multienzyme systems.
Such systems include either a collection of free cellulases or/and multicomponent
complexes called cellulosomes.
This chapter deals with the structure and properties of cellulose. After a description of the cellulose macromolecule at the molecular level in Chapter 1,
two higher structural levels will be ...analyzed here.
Second Foreword Wertz, Jean-Luc; Mercier, Jean P.; Bédué, Olivier
Cellulose Science and Technology
Book Chapter
Biomass could be one of those renewable sources for energy, but it brings its
own dilemmas; if biomass combustion is known from the early stages of
humanity, still providing one tenth of primary ...energy supplies, it is too often
at the cost of non-sustainable deforestation practices; if biofuels can be manufactured from sugars, starch, vegetable oils, they could readily enter in direct
competition with food markets if they develop without all the necessary
cautions.
