Hydrolysis is a chemical reaction in which water
reacts with and splits another substance to form one or
more entirely new substances. Examples are the
breakdown of sucrose (cane sugar) to glucose and fructose
and the conversion of starch to glucose in the
presence of suitable catalysts (fig. 21). Glucose is the
basic component of cellulose. Hydrolysis reduces the
chain length or the size of the molecules. This increases
solubility. Acid hydrolysis (hydrolysis in the presence of
acid catalysts) is a very important reaction in the
manufacture of fiberboard. In the pulping process it
causes a breakdown and subsequent loss of part of the
hemicelluloses. The acidity necessary for the hydrolysis
reaction is developed by the simultaneous formation of
acetic acid and formic acid from wood carbohydrates.
The hydrolysis of the hemicelluloses reduces pulp yield
and loads the process water with biodegradable sugars.