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Miscanthus for Bio-based Products
11.2.5 Hemicelluloses
Hydrothermal processes may be used to extract hemicelluloses from
Miscanthus at temperatures from 160°C to 180°C (Wang et al., 2018; Xiao
et al., 2017). Arabinoxylans are the most common hemicellulose polymers
in Miscanthus (Schäfer et al., 2019). Hydrolysis of the hemicellulose yields
mostly xylose and a small amount of arabinose (Schäfer et al., 2019). For some
applications of cellulose, it is beneficial to remove most of the hemicellulose.
There is a market for xylose as a raw material for fermentation and other uses.
11.3 Processing of Miscanthus to Fibers, Pulp, and Papers
Pulp for paper production is divided into three main categories (Liu et al.,
2018): wood fiber, nonwood fiber, and waste paper; the shares of which in
the pulp and paper industry are currently 63%, 3%, and 34%, respectively.
Nevertheless, the increasing potential of nonwood resources is a consequence of decreasing of forest resources (Lwako et al., 2013). The overall
potential of nonwood plant raw materials which can be processed to pulp
is about 2.5 billion tons per year and is renewed annually (SaijonkariPahkala, 2001). The use of nonwood plant raw materials in the production of
pulp goes back to the origins of the paper industry and remains an urgent
focus for the industry as forestry resources diminish (Ververis et al., 2004).
Promising alternative plants include different crops, and Miscanthus is a
leading candidate (Danielewicz et al., 2018) due to its high growth rates,
high lignin content, and ability to grow on marginal and degraded lands,
where the food production is prohibited. This latter factor eliminates competition with food production. The pulp from perennial grass biomass can
to be added to the existing wood feedstock (Bocianowski et al., 2019a, b), be
processed separately (Danielewicz et al., 2015), or mixed with waste papers
(Cappelletto et al., 2000).
Generally, the paper manufacturing process has several stages, i.e., raw
material preparation and handling, pulp manufacturing, pulp washing
and screening, chemical recovery, bleaching, stock preparation, and papermaking (Bajpai, 2018). Paper production is basically a two-step process in
which a fibrous raw material is first converted into pulp, and then the pulp
is converted into paper. The harvested wood is first processed so that the
fibers are separated from the unusable fraction of the wood, the lignin. Pulp
making can be done mechanically or chemically. The pulp is then bleached
and further processed, depending on the type and grade of paper that is to
be produced. In the paper factory, the pulp is dried and pressed to produce
paper sheets. Post use, an increasing fraction of paper and paper products is
recycled, which avoids landfilling or incinerating.
Miscanthus for Bio-based Products
11.2.5 Hemicelluloses
Hydrothermal processes may be used to extract hemicelluloses from
Miscanthus at temperatures from 160°C to 180°C (Wang et al., 2018; Xiao
et al., 2017). Arabinoxylans are the most common hemicellulose polymers
in Miscanthus (Schäfer et al., 2019). Hydrolysis of the hemicellulose yields
mostly xylose and a small amount of arabinose (Schäfer et al., 2019). For some
applications of cellulose, it is beneficial to remove most of the hemicellulose.
There is a market for xylose as a raw material for fermentation and other uses.
11.3 Processing of Miscanthus to Fibers, Pulp, and Papers
Pulp for paper production is divided into three main categories (Liu et al.,
2018): wood fiber, nonwood fiber, and waste paper; the shares of which in
the pulp and paper industry are currently 63%, 3%, and 34%, respectively.
Nevertheless, the increasing potential of nonwood resources is a consequence of decreasing of forest resources (Lwako et al., 2013). The overall
potential of nonwood plant raw materials which can be processed to pulp
is about 2.5 billion tons per year and is renewed annually (SaijonkariPahkala, 2001). The use of nonwood plant raw materials in the production of
pulp goes back to the origins of the paper industry and remains an urgent
focus for the industry as forestry resources diminish (Ververis et al., 2004).
Promising alternative plants include different crops, and Miscanthus is a
leading candidate (Danielewicz et al., 2018) due to its high growth rates,
high lignin content, and ability to grow on marginal and degraded lands,
where the food production is prohibited. This latter factor eliminates competition with food production. The pulp from perennial grass biomass can
to be added to the existing wood feedstock (Bocianowski et al., 2019a, b), be
processed separately (Danielewicz et al., 2015), or mixed with waste papers
(Cappelletto et al., 2000).
Generally, the paper manufacturing process has several stages, i.e., raw
material preparation and handling, pulp manufacturing, pulp washing
and screening, chemical recovery, bleaching, stock preparation, and papermaking (Bajpai, 2018). Paper production is basically a two-step process in
which a fibrous raw material is first converted into pulp, and then the pulp
is converted into paper. The harvested wood is first processed so that the
fibers are separated from the unusable fraction of the wood, the lignin. Pulp
making can be done mechanically or chemically. The pulp is then bleached
and further processed, depending on the type and grade of paper that is to
be produced. In the paper factory, the pulp is dried and pressed to produce
paper sheets. Post use, an increasing fraction of paper and paper products is
recycled, which avoids landfilling or incinerating.