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How the Ethylene Gas Guardian
Works
The ethylene molecule
is very reactive and is readily oxidized into a state
that will not do damage to produce. There are several
ways that may be used to remove ethylene from produce
storage areas. One of the simplest and safest methods
is to oxidize it with potassium permanganate.(For
those of you who, like me, enjoy chemistry, a link to
the reaction is given at the bottom of this page).
This reaction can remove ethylene to very low levels.
Potassium permanganate (KMnO4) is used in a number of
familiar applications, such as in drinking water
treatment systems.
Substrate
Since we have chosen to use potassium permanganate as
our oxidizer, we need to choose a way to make it the
most available for reacting with the ethylene gas in
our refrigerator. We need a support medium that will
allow the ethylene to contact the oxidizer so it may be
reacted away. Industry does this in several ways, or
course, but for the home refrigerator application we
like the use of natural zeolite. Zeolite is a pure form
of volcanic ash that has a very high surface area,
providing an ideal substrate for the ethylene oxidation
to occur.
Natural zeolite is often used as an odor absorber
and a humidity stabilizer in refrigeratores, closets,
and automobiles. The very high surface area traps odor
molecules and absorbs water when humidity is too high -
releasing it back into the atmosphere when it gets too
dry. Of course, the zeolite used in the Ethylene Gas
Guardian serves those purposes, but its function as a
support medium for removing ethylene is its main
purpose.
The zeolite used in the E.G.G.
is from an exceptionally high quality deposit.
After the crushing and grading of the zeolite,
there are no fines and virtually no dusting.
The potassium permanganate is applied to the
zeolite using a patented process that lays the
active chemical on the surface uniformly all
the way to the center of the zeolite. The
resulting product has the highest reactive
chemical, 6%, and the best cationic exchange
capacity of any in the industry.
Packets
The KMnO4 coated zeolite is then packaged in
Tyvek packets that are water resistant, but are
highly permeable to ethylene. It contains the
zeolite and prevents any fines from getting out
of the eggs and onto your produce. Although the
contents are not harmful, they can be colorful,
making the produce less attractive to eat. |
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"Eggs"
A very important feature in the Ethylene Gas
Guardian is its egg design. In order to
maintain the very low concentrations of ethylene
necessary to protect the produce in your refrigerator,
there has to be a lot of contact between the air and
the potassium permanganate. If the zeolite packet were
dropped into your produce crisper as is, it would
quickly find its way to the bottom of the drawer.
The vented egg design
prevents cutting off the circulation that is
required for effectiveness from happening.
It is unlikely that anything could
inadvertently fall onto the egg that would
totally restrict air flow. Ideally, the eggs
should be placed in separate drawers to further
limit the possibility that restricted air flow
would reduce its effectiveness. By having two
points of possible contact between the ethylene
in the air and the KMnO4 on the zeolite, the
lowest possible level of ethylene can be
maintained.
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Time for Replacement
The reaction between the ethylene and potassium
permanganate oxidizes the ethylene away and, or course,
reduces the potassium permanganate away, too. The
amount of potassium permanganate available will last at
least 3 months in most home refrigerators. After 3
months you should replace the E.G.G., or the packets
inside the egg. Refill packets are available.
Don't throw the spent zeolite away !
We recommend that you put the spent zeolite on your
plants. The zeolite is a natural soil and the MnO2
provides trace minerals to the soil. Your plants will
love it.
Want to know the chemistry behind it all? Click here to see the chemistry
in action.
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