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Lignin confers structural integrity to plants. Lignin is so heterogeneous and so recalcitrant that its value is almost exclusively measured as a fuel. hemicellulose is composed of branched polysaccharides. A particular problem is that hemicellulose is covalently linked to lignin, usually through ferulic acid component of the
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. [1] Lignins are particularly important in the formation of cell walls , especially in wood and bark , because they lend rigidity and do not rot easily.
[59] [60] The environmental impact of bioplastics is often debated, as there are many different metrics for "greenness" (e.g., water use, energy use, deforestation, biodegradation, etc.). [61] [62] [63] Hence bioplastic environmental impacts are categorized into nonrenewable energy use, climate change, eutrophication and acidification. [64]
Like other polymers, biopolymers consist of monomeric units that are covalently bonded in chains to form larger molecules. There are three main classes of biopolymers, classified according to the monomers used and the structure of the biopolymer formed: polynucleotides, polypeptides, and polysaccharides.
Torrefaction is a thermochemical treatment of biomass at 200 to 320 °C (392 to 608 °F). It is carried out under atmospheric pressure and in the absence of oxygen.During the torrefaction process, the water contained in the biomass as well as superfluous volatiles are released, and the biopolymers (cellulose, hemicellulose and lignin) partly decompose, giving off various types of volatiles. [4]
However, conversion of xylose, the pentose sugar of hemicellulose hydrolyzate, is a limiting factor, especially in the presence of glucose. Moreover, it cannot be disregarded as hemicellulose will increase the efficiency and cost-effectiveness of cellulosic ethanol production.
Some species of bacteria secrete it to form biofilms. [5] Cellulose is the most abundant organic polymer on Earth. [6] The cellulose content of cotton fibre is 90%, that of wood is 40–50%, and that of dried hemp is approximately 57%. [7] [8] [9] Cellulose is mainly used to produce paperboard and paper.
The Alpena biorefinery plant in the USA. A biorefinery is a refinery that converts biomass to energy and other beneficial byproducts (such as chemicals). The International Energy Agency Bioenergy Task 42 defined biorefining as "the sustainable processing of biomass into a spectrum of bio-based products (food, feed, chemicals, materials) and bioenergy (biofuels, power and/or heat)". [1]