Cellulose

1. Cellulose By: Edel Kerins, Joanne Moran and Marc Falconer

2. What is cellulose? • Cellulose (C6H10O5)n is a long-chain polysaccharide carbohydrate, of beta-glucose. • It forms the primary structural component of plants and is not digestible by humans Structure of Cellulose

3. History • Cellulose is the most abundant naturally occurring organic substance • Being found as the principal component of cell walls in higher plants where it provides the main structural feature. • It was first noted as such in 1838 by Anselm Payen. • It occurs in almost pure form in cotton fibre at 98% in combination with lignin and hemicellulose. • Cellulose is the most abundant form of living terrestrial biomass.

4. Applications • Cellulose is processed to make cellophane and rayon and more recently Modal- a textile derived from beech wood cellulose. • Cellulose is also used within the laboratory as a solid-state substrate for thin layer chromatography. • Cellulose is a major constituent of paper.

5. Derivatives • The hydroxyl groups of cellulose can be partially or fully reacted with various chemicals to provide derivatives with useful properties. • They have the general formula Cellulose-O-R where the oxygen can be any of the cellulose hydroxyls. • Cellulose esters and cellulose ethers are the most important commercial materials. • Among the esters are cellulose acetate and triacetate, which are film and film forming materials.

6. Uses of Cellulose • Cellulose has many uses such as the following. • anticake agents • Emulsifier • Stabiliser • Dispersing agent • Thickener • Gelling agent • Most important use is of holding on to water

7. Treatments of Cellulose • Industries of all kinds- food processing, forest products and pulp and paper, face major problems with disposal of wastes derived from plant material. • Cellulose comprises nearly half the dry weight of most plant material. • Carbon fiber has been described as a fiber containing at least 90% carbon obtained by the controlled pyrolysis of appropriate fibers. • The Term “graphite fiber” is used to describe fibers that have carbon in excess of 99%. • Large varieties of fibers called precursors are used to produce carbon fibers of different morphologies and different specific characteristics. • The most prevalent precursors are ployacrylonitrile, cellulosic fibers petroleum or coal tar pitch and certain phenolic fibers.

8. Treatment of cellulose • Carbon fibers are manufactured by the controlled pyrolysis of organic precursors in fibrous form. • It is a heat treatment of the precursor that removes the oxygen, nitrogen and hydrogen to form carbon fibers. • There are three successive stages in the conversion of PAN precursor into high- performance carbon fibers. • Oxidative Stabilisation • Carbonisation • Graphitisation

9. Pre-treatment of fermentable CHO products for bioethanol production • Physical and chemical pre-treatment of cellulose • It is necessary for hydrolysis and fermentation steps to occur for bioethanol production. • Pre-treatment processes are normally applied on different substrates. • Acidic hydrolysis • Steam explosion • Wet oxidation

10. Pre-treatment of fermentable CHO products for bioethanol production • One problem associated with pre-treatment methods is the generation of certain compounds that are inhibitory towards micro organisms • Degradation problems associated with later fermentation can be avoided by wet oxidation. • A project underway in co-operation with Elsam, an industrial partner is to develop hydrothermal treatment of wheat straw on a pilot plant scale. • The main objective of the project is to pre-treat plant fibre biomass.

11. Pre-treatment of fermentable CHO products for bioethanol production • Co- Combustion of coal and straw • Enzymatic convertibility of cellulose • The first aim is to evaluate grass clover as feedstock material for fermentation.

12. Environmental Benefits of cellulose conversions • Biodiesel is a clean burning alternative fuel. • It is made by chemically combining any natural oil or fat with an alcohol. • This process is known as transesterification • Products produced from this process are: *Methyl soyate *glycerine Current biodiesel market are mass transit, marine and other environmentally sensitive areas such as mines.

13. Ethanol • It reduces smog and green house gas emissions. • It contains 35% oxygen. • It does not contain sulphur • Environmental benefits increase as biodiesel and cellulose ethanol grow. E.g. Renewable fuel in Ontario.

14. Cellulose insulation • Made from recycled wood fiber, primarily newspaper • Waste paper is a major source of the waste stream • Reducing the amount of paper that ends up in landfill • When you choose cellulose insulation it reduces the major problem of solid waste disposal. • The main advantages: • Saves more energy • Makes home safer • Fills existing walls with fewer voids and stops air in filtration better

15. Utilization of Cellulose and examples of cellulose based products. • Cellulose is the major constituent of Cotton (98%)and Wood(40-50%).Cotton and wool are the major reservoirs for all cellulose products such as paper, textiles and construction materials. • The Paper production industry is of great economic significance to the world, is a multi-billion dollar concern and relies on the manipulation of the chemical properties of cellulose. • The Textile industry is of great economic significance and relies heavily on cellulose both for natural and synthetic fibres. • The construction industry also utilizes cellulose in products i.e. Carbon fibre reinforced polymers (CFRP’s) and cellulose insulation.

16. Cellulose based Products • Cellulose nitrate. This was the first successful plastic. It was invented in 1869 by Alexander Parkes. It is used in making toilet pieces and other industrial items. • Cellulose acetate. It is used in making packaging materials, toys, tools etc. It is the cheapest raw material produced. • Ethyl cellulose. This is produced by treating alkali cellulose with either ethyl chloride or ethyl sulphate. It is used in flashlight cases and electrical appliance parts. It is the lightest and most expensive of the cellulosics. • Methyl cellulose. Is non toxic and is a weak adhesive. In its pure state it is used for cleaning the spines of books. It works as an excellent solvent of hide glue and some modern adhesives.

17. Additional Cellulose based products • Microcrystalline Cellulose (MCC). This is basically refined cellulose with the amorphous region and impurities removed. • Hydroxypropyl Methyl Cellulose. This is the end product of a chemical treatment of cellulose. Can be used as an emulsifier, gelling agent, thickener, among other things. • Rayon. This is formed by chemical and pressure treating wood pulp. It was commercially produced for first time in 1884 for use as a textile. It is a very useful fibre.

18. Some photos of Cellulose based products. Ethyl cellulose (finished products) Ethyl Cellulose powder Antique nitro cellulose based shaving kit Methyl cellulose powder

19. Microbial Cellulose: A new resource for wood, paper, textiles and food products • What is Microbial Cellulose? Cellulose which is formed by an advanced purple bacterium such as Acetobacter xylinum. • How is it formed? The production of glucose molecules by individual Acetobacter cells. Each cell can produce 108 glucose molecules per hour. The end product is a bundle of sub-microscopic fibrils, this mesh produces a pellicle which cements the mesh together. Pure cellulose is the result. • What could it be used for? Microbial cellulose has two great properties. It is very strong in the never dried state and hold hundreds of times its own weight in water. • What is the future for Microbial Cellulose?

20. Cellulose and the Environment • Cellulose and the Carbon cycle. Cellulose can be imagined as giant carbon “sink”. Carbon incorporated in cellulose can remain there for a long time. • Cellulose in the oceans. The majority of cellulose in the oceans is produced by unicellular algae or plankton. • Unicellular plankton

21. Cellulose and the Environment continued. • How we can improve the environment by improving our utilization of waste cellulose and developing products based on waste cellulose as alternatives. • What efforts need to be taken in order to use the resources of waste cellulose more effectively and thus improve the global environment. • Conclusions. • Right hand side: Photo of deforestation in Amazon basin