Hydrogen peroxide, a useful all-purpose disinfectant, is found in most medicine cabinets in the
developed world.
But in remote villages in developing countries, where it could play an important role in health
and sanitation, it can be hard to come by.
Now, a process developed at MIT could lead to a simple, inexpensive, portable device
that could produce hydrogen peroxide continuously from just air, water, and electricity, providing
a way to sterilize wounds, food-preparation surfaces, and even water supplies.
Even at low concentrations, hydrogen peroxide is an effective antibacterial agent, and after
carrying out its sterilizing function it breaks down into plain water, in contrast to other
agents such as chlorine that can leave unwanted byproducts from its production and use.
Hydrogen peroxide is just water with an extra oxygen atom tacked on — it’s H2O2, instead
of H2O.
That extra oxygen is relatively loosely bound, making it a highly reactive chemical eager
to oxidize any other molecules around it.
It’s so reactive that in high concentrations it can be used as rocket fuel, and even concentrations
of 35 percent require very special handling and shipping procedures.
The kind used as a household disinfectant is typically only 3 percent hydrogen peroxide
and 97 percent water.
Because high concentrations are hard to transport, and low concentrations, being mostly water,
are uneconomical to ship, the material is often hard to get in places where it could
be especially useful, such as remote communities with untreated water.
(Bacteria in water supplies can be effectively controlled by adding hydrogen peroxide.)
As a result, many research groups around the world have been pursuing approaches to developing
some form of portable hydrogen peroxide production equipment.
Most of the hydrogen peroxide produced in the industrialized world is made in large
chemical plants, where methane, or natural gas, is used to provide a source of hydrogen,
which is then reacted with oxygen in a catalytic process under high heat.
This process is energy-intensive and not easily scalable, requiring large equipment and a
steady supply of methane, so it does not lend itself to smaller units or remote locations.
Other processes developed so far for potentially portable systems have key limitations.
For example, most catalysts that promote the formation of hydrogen peroxide from hydrogen
and oxygen also make a lot of water, leading to low concentrations of the desired product.
Also, processes that involve electrolysis, as this new process does, often have a hard
time separating the produced hydrogen peroxide from the electrolyte material used in the
process, again leading to low efficiency.
The MIT team solved the problem by breaking the process down into two separate steps.
First, electricity is used to break down water into hydrogen and oxygen, and the hydrogen
then reacts with a “carrier” molecule.
This molecule — a compound called anthroquinone, in these initial experiments — is then introduced
into a separate reaction chamber where it meets with oxygen taken from the outside air,
and a pair of hydrogen atoms binds to an oxygen molecule (O2) to form the hydrogen peroxide.
In the process, the carrier molecule is restored to its original state and returns to carry
out the cycle all over again, so none of this material is consumed.
The process could address numerous challenges, by making clean water, first-aid care for
wounds, and sterile food preparation surfaces more available in places where they are presently
scarce or unavailable.