A short overview about cellulose and its worthy application. The challenging application of nanocellulose in SULTAN project will be: froth flotation. Froth flotation is a technique for selectively separating hydrophobic materials from hydrophilic materials, it has been widely used to recover valuable minerals from ore.
Dear readers,
My name is Feliciana and I am an industrial chemist from Italy. As part of the SULTAN project, I am the ESR 4 and I am currently located in Oulu, a lovely city in the Center of Finland.
Well! I can´t wait to deeply explore this amazing Finland: the land of a thousand lakes, forests and traditional sauna, the land of Northern Light and the midnight sun.
Don´t panic…! I´m not in a hurry, I will spend some years here for my PhD research.
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Figure 1 – 2. Kuivasjärvi lake; at midnight.
Figure 1 – 2depict a wonderful and typical Finnish landscape, but I cannot admire it without looking at the huge multitude of trees. Are you wondering where I am driving at?!…. CELLULOSE, of course!
Wood obtained from forest trees is the predominant source of cellulosic fiber for pulp and paper manufacture. Wood is composed principally of carbon, hydrogen and oxygen, and depending on its nature, different inorganic compounds are also contained. The elemental constituents of wood are combined into organic polymers (from Greek, polyplus metro, meaning “many parts”): cellulose, hemicellulose and lignin.
Cellulose is the most important component of wood and it constitutes slightly less than one-half the weight of both hardwood and softwood. The proportion of lignin and hemicellulose varies widely among species and between the hardwood and softwood groups.
Table 1. Organic constituents of wood; % dry weight.
Starting from trees up to the purified cellulose fibers, many ways to process the wood can be required: mechanical, chemical, thermochemical, or thermal conversion methods figure 3.
Figure 3.Wood hierarchical structure: from tree to cellulose.
Cellulose was discovered in 1838 by the French chemist Anselme Payen, who isolated it from plant matter and determined its chemical formula.
In 1855 Alexander Parkes, obtained the first celluloid material, which was patented as Parkesine in 1862, then “Celluloid” was dubbed 10 years later (1872) by Hyatt´s sibling. Following, cellophane discovered by Jacques Edwin Brandenberger, a Swiss chemist, has been patented in 1912.
For the first time, in 1992, cellulose was synthesized in vitro via a non – biosynthetic path.
Cellulose, the most abundant natural polymer on Earth, is a polysaccharide which form part of the group of molecules known as carbohydrates, classified according to their main monosaccharide components´. In our daily life we have a variety of examples of those molecules and I am sure that if I mention three “single” sugar (monosaccharide) I will bring back in our mind something familiar. Those single sugars are: glucose, galactose and fructose, same molecular formula C6H12O6, but different arrangement of atoms.
Those three monosaccharides can be linked together forming a disaccharide. We might know sucrose, the common table sugar and the most important source of energy for many cells (consisting of glucose and fructose) or lactose, the main sugar in milk (consisting of glucose and galactose).
Although, cellulose is a carbohydrate, it cannot be a source of food for human, because we do not have the enzymes (cellulase) able to convert cellulose to metabolically useful glucose.
Cellulose is a linear homopolysaccharide, consisting of β-D-glucose units (C6H10O5)n repeated, n indicates the degree of polymerization, which in wood cellulose is supposed to be approximately 10.000 (figure 4).
Figure 4. β-D-glucose (a). Structure of cellulose (b).
Cellulosic nanoparticles or nanocellulose provide a unique renewable building block on which materials with improved performance and new functionality can be prepared. Cellulose is an active chemical because of the presence of three hydroxyl groups (-OH), which are responsible for the reactions of cellulose.
The chemical functionalization of cellulose nanofibrils (CNF) means to replace the hydroxyl groups (-OH) with new functional groups, depending on the final target.
This modification has proved to be extremely useful to tailor the nanofibers polarity and or to add another functionality to the surface of the nanofibers, thereby increasing the potential scope for the use of CNF.
Up to now, cellulose has been largely used in paper manufacturing, textile industries, optical devices, medicine and life science, as rheological modifiers and others.
The aim of my research is to functionalize nanocellulose with chemical groups able to enhance its hydrophobicity properties, so as to obtain nanocellulose materials with less affinity to water.
The challenging application of nanocellulose in SULTAN project will be: froth flotation. Froth flotation is a technique for selectively separating hydrophobic materials from hydrophilic materials, it has been widely used to recover valuable minerals from ore. Interesting, isn´t it?
Unfortunately, I will not talk about froth flotation, I cannot reveal entirely my project right now 😊. I highly recommend you stay tuned and keep reading our blogs, we will keep you up to date with our research progress.
References
A. Dufresne, Nano-Cellulose, From Nature to High Performance Tailored Materials, 2012. Walter de Gruyter, Berlin.
A. Payen, Mémoire sur la composition du tissu propre des plantes et du ligneux, Comptes Rendus1838, vol. 7, pp. 1052–1056.
J. L. Bowyer, R. Shmulsky, J. G. Haygreen, Forest Products and Wood Science, Fourth edition 2003. Blackwell Publishing, Ames, Iowa.
R. Alen, I. Forsskåhl, B. Holmbom, P. Stenius, Papermaking Science and Technology, Book 3 Forest Products Chemistry 2000,Fapet Oy, Helsinki.
S. Kobayashi, K. Kashiwa, J. Shimada, T. Kawasaki, S. Shoda, Enzymatic polymerization: The first in vitro synthesis of cellulose via nonbiosynthetic path catalyzed by cellulase,Macromolecular Symposia 1992, vol. 54-55, pp. 509-518