Explosion- How it works….
the Chemistry behind it all )
main components of fibrous materials are cellulose and lignin.
The lignin acts like glue and binds the cellulose chains together. In
order to utilize these fibers, it is necessary to separate the lignin from the
cellulose. In the past, it has only been possible to break the bonding between
the cellulose and the lignin through very expensive and highly polluting
chemical pulping processes. The
steam explosion process can break the bond between the cellulose and the lignin
using only high pressure steam. Steam
Explosion Technology has application in pulping of non-woody material, cellulose
derivatives, and fractionation.
Steam Explosion technology provides industry with a low cost and environmentally
friendly route to such products as pulp for paper, cellulose derivatives for
food application, and specialty chemicals . The continuous process uses high
pressure steam to free the cellulose from materials such as wood, straw and
sugarcane bagasse. The high temperature of the process eliminates or greatly
reduces the requirements for using chemicals associated with current industrial
explosion is an autohydrolysis process, meaning water is used in the reaction to
break molecules into their fragments, in our case wood, peanut shells, and other
biomass. Its effect on biomass include:
splitting of accessible glycosidic bonds,
2) the splitting of alpha-ether linkages of lignin,
3) the splitting of lignin-carbohydrate complex bonds, and
4) minor chemical modification of lignin and carbohydrates.
bonds are how carbohydrates attach to one another. The hydrolysis of a
glycosidic bond consumers water which is needed for the process to work.
splitting ligin at the alpha position it increases the polarity of lignin. If
enough linkages are split it will eventually get dissolution of the polymer
causing some depolymerization of ligin.
major carbohydrate found in wood is glucose, the building block of cellulose.
This process tries to break the hydrogen and possible covalent bonds between the
cellulose, hemicellulose, and lignin to be used as industrial raw materials.
order to obtain cellulose, hemicellulose, and lignin from the exploded fibers,
fractionation, or separation, must be carried out.
consequence of the steam explosion on the structure and behavior of
lignocellulosic materials is the solubility of the biomass in neutral and alkali
solvents. When exposed to a neutral solvent the lignin softens such that when
the pulp processed under higher temperatures it tends to allow the lignin to
spread amongst the fibers. The lignin then hardens stiffening the sheet. An
alkaline solvent could cause the lignin to dissolve onto the pulp fibers, like
the Kraft process.
steam assisted fractionation of biomass by steam explosion produces two useful
polymer fractions. First is a
partially hydrolyzed cellulose fraction which normally results in a 40-50%
yield. Second is a pure,
alkali-soluble, lignin fraction which results in a 15-25% yield.
(Yield depends primarily on the severity of the steam explosion process