Plant fibres sourcing

Figure 5.11 Production (in metric tons) of some plant fibres. Source FAO (2004)...

Use of renewable feedstocks is most likely where they can compete economically with petrochemically derived materials. This already happens in many areas, and it is sometimes forgotten that even in a world that seems to be dominated by chemicals and materials from fossil carbon and other non-renewable sources, industry already uses annually 19.8 MT of vegetable oils, 22.5 MT starch, 28.4 MT of plant fibres and 42.5 MT of wood pulp. These all compete on price and performance with synthetic alternatives. 

The overall picture is of the wood-based panels sector continuing to grow as products are developed that meet new customer requirements. The processes have demonstrated an adaptability to different fibre sources, both in form and in species that has allowed plants to be established in most parts of the world, primarily to meet local demand, but also with a significant export component to those areas where fibre supplies are fully committed. 

Marek, J., Anonov, V., Bjelkova, M., Smirous, P., Fischer, H., Janosik, S., 2008. Enzymatic bioprocessing—new tool of extensive fibre source. In International Conference on Flax and Other Bast Plants, 21-23 July, Saskatoon, Canada. 

The two main sources of natural fibres are plants and animals. The main component of animal based fibres is various proteins examples include mohair, wool, silk, alpaca, angora, etc. The components of plant fibres are cellulose microfibrils dispersed in an amorphous matrix of lignin and hemi-cellulose examples include cotton, jute, flax, ramie, sisal, hemp, etc. 

Hibiscus sabdariffa or in common name roselle, is an annual fibre plant, has been found to be an important source of fibres for a number of application since ancient times. The bast fibre has high potential as a reinforcing fibre in polymer composites. Hibiscus sabdariffa plant fibre is abundantly found in the Himalayan region, especially in Himachal Pradesh. It is traditionally used by the locals as socks, boots, mats, ropes, bags, etc. 

Of the natural fibres, vegetable or plant fibres are the only ones that have suitable properties to meet technical requirements cost effectively for use as natural geotextiles. Plant fibres can be further classified according to the part of the plant as principal sources from which they are extracted bast fibres, leaf fibres and fruit or seed fibres. Fig. 4.1 shows a brief classification of textile fibres. 

Some by-products from the food industry contain high proportions of plant cell walls which can be used in human nutrition to produce "dietary fibre" or "functional fibre", i.e. compounds which can be used for their water-holding/binding properties, oil-binding capacity,... or as a source of polysaccharides such as pectins which are suitable after extraction, as gelling or thickening agents. 

Many plant products are very rich in cell wall materials. Cereal brans, seed hulls, various pulps (including beet pulp), citrus peels, apple pomace... are typical exemples of such by-products (1,2). They can be used after simple treatments as dietary fibres, functional fibres or bulking agents, depending on the nutritional claims (2). They can be used also eis sources of some polysaccharides. 

In addition to fibre obtained directly from plant sources by chemical or mechanical treatment (virgin fibre), recycled fibre is also used and to an increasing extent for paper and board production. A breakdown of world fibre usage is given in Table 1.2 and the subject... 

Sulphuric acid is the largest volume chemical in the world with an annual production of about 180 mill, t/year which is used primarily for phosphate fertilizers, petroleum alkylation, copper ore leaching and in smaller quantities for a number of other purposes (pulp and paper, other acids, aluminium, titanium dioxide, plastics, synthetic fibres, dyestuffs, sulphonation etc.). The major sulphur sources for sulphuric acid production are sulphur recovered from hydrocarbon processing in the refineries and from desulphurisation of natural gas, SO2 from metallurgical smelter operations, spent alkylation acid, and to a minor extent mined elemental sulphur and pyrites. A simplified flow sheet of a modem double-absorption plant for sulphuric acid production from sulphur is shown in Fig. 1. 

Cotton is the richest source of cellulose, since cotton fibres contain as much as 85-97% cellulose. Cotton consists of the nap covering the seeds of the cotton plant (Gossypium) which grows throughout the whole year in a warm, moderately damp climate (Egypt, southern areas and of United States, and U.S.S.R., India, and China Pacific Islands). The length, thickness and colour of the nap depend on the variety of the plant and on the climate in which it is cultivated. 

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