Wednesday, 19 August 2015 00:00 Written by 

Lignin is a by-product of paper and pulp production.

Lignin is the second most abundant natural polymer in the world and is a basic component of the cell walls of plant cell wall. It is composed of both aromatic and aliphatic functionality.


Plant lignins can be broadly divided into three classes: softwood (gymnosperm),  hardwood (angiosperm) and grass or annual  plant (graminaceous) lignin . Three  different phenylpropane units, or monolignols,  are responsible for lignin biosynthesis . Guaiacyl lignin is composed principally of coniferyl alcohol  units, while guaiacyl- syringyl lignin contains monomeric units from  coniferyl and sinapyl alcohol. In general,  guaiacyl lignin is found in softwoods while guaiacyl-syringyl lignin is present in  hardwoods. Graminaceous lignin is composed mainly of  p -coumaryl alcohol units.  These three lignin precursors are shown in Figure 1.


Sources of Lignin:

1. Pulp & Paper Mills:

2. Ligno-cellulosic Ethanol Industries:

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