Page 38 - Modeling of Chemical Kinetics and Reactor Design

8 Modeling of Chemical Kinetics and Reactor Design

1. CH + H O → 3 H + CO (1-27)
2
2
4
2. CH + 2 H O → 4 H + CO 2 (1-28)
2
4
2
3. CO + H O → CO + H 2 (1-29)
2
2
4. CH + CO → 2 CO + 2 H 2 (1-30)
4
2
5. CO H+ 2 [ C H O (1-31)
+

2
6. CH [ C 2+ H 2 (1-32)

4
7. 2CO [ C + CO 2 (1-33)

BIOCHEMICAL REACTION: CONVERSION
OF GLUCOSE TO GLUCONIC ACID
The fermentation of glucose to gluconic acid involves oxidation of
the sugar in the aldehyde group (RCHO), thereby converting it to a
carboxyl group (RCOOH). The conversion process is achieved by a
micro-organism in the fermentation process. The enzyme glucose
oxidase that is present in the micro-organism converts the glucose to
gluconolactone. The gluconolactone is further hydrolyzed to form the
gluconic acid.
The enzyme glucose oxidase is useful in medicinal applications
where glucose or oxygen removal is required. This enzyme prevents
the browning reaction, or a Mailland reaction, when dried egg powders
are darkened due to a reaction between glucose and protein. Also, the
presence of oxygen in the production and storage of orange soft drinks,
dried food powders, canned beverages, salad dressing, and cheese
slices can be avoided by adding glucose oxidase. Since the activity
of the enzyme is maintained for a long time at storage temperature,
such enzyme additions increase the shelf-life of food products. This
is achieved by the removal of oxygen that diffuses through food
packaging [2].
The hydrogen peroxide produced in the glucose oxidase catalyzed
reaction has an antibacterial action. The addition of a catalase catalyzes
the decomposition of hydrogen peroxide to water and oxygen.

REACTION MECHANISMS

The reaction mechanisms in the fermentation of glucose to gluconic
acid are: