Al Einstein, Water
Treatment Specialist
By Alicia Kenney
Originally Published: CSTN – August 2004
T
o a young and relatively inexperienced engineer (“newbie”), it seems
almost unthinkable that there was a time when batched-processed cold lime
softening was considered cutting edge technology. Nonetheless, it was!
Today, industry leaders are working to find innovative applications of
membrane technology such as ultrafiltration and reverse osmosis to meet the
needs of clients who require the efficient production of high quality water. In
the meantime, it remains important to look ahead. The increasingly stringent
water quality regulations, driven by sensitive new equipment that can detect
contaminants in the parts per trillion range, and the economics surrounding
water and energy use ensure that the future of water treatment will lead to
even greater sophistication and technological innovation.
Where will we find the next advance? No one can be certain, but the answer
may be in Albert Einstein’s doctoral dissertation of 1905. That’s right – the
same crazy-haired Einstein who brought us E = mc2, special and general
relativity, the photoelectric effect and other revolutionary ideas. Physicists
around the world continue to study and expand on his original theories. So
far they have brought us GPS units, DVD players, digital cameras, and
automatic doors - gadgets that have become nearly indispensable parts of our
everyday lives. The future innovations have no limit and could include ultrafast and long-life computers made possible by room-temperature
superconductivity, space and time travel inspired by general relativity or,
more relevant to us, better water purification using Brownian ratchets.
Brownian Motion
Before Einstein was captivated with large scale theories addressing the
nature of space, time and the universe, he studied the nature of
submicroscopic molecules. He worked out the mathematical laws governing
“Brownian motion”, a phenomenon that was discovered by botanist Robert
Brown in 1827 and had stumped scientists ever since. Brown observed that
tiny particles in water dance around as if they are alive. It was Einstein who
figured out that that the “random walk” (also known as “drunkard’s walk”)
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motion of the particles is a result of the bombardment by surrounding water
molecules.
While the motion of the water molecules is too small, fast and numerous to
observe directly, when using a microscope the effect on the particles over
time can be seen in their erratic movement. Incidentally, Einstein used this
phenomenon as evidence to support the then-controversial theory that heat
was simply the random motion of molecules!
Brownian Ratchets
Einstein’s mathematical explanation of Brownian motion has already found
many useful applications varying from predicting how substances diffuse
though liquids to the less intuitive use in analyzing stock markets. One
exciting new development has been the design of Brownian ratchets, a device
designed to convert the random motion of molecules into useful work. The
study of potential applications of Brownian
ratchets has led to an improved
understanding of the mechanisms involved
in many molecular-level biological
processes including the transport of proteins
and even DNA.
Brownian Sieve
At the Max Planck Institute of
Microstructure Physics in Weinburg,
Germany Sven Matthias and Frank Muller
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created a new type of sieve based on Brownian ratchets by etching thousands
of parallel channels into a thin silicon wafer.
Each channel acts as a Brownian ratchet as it widens and narrows in a series
of bottlenecks. These bottlenecks exploit Brownian motion to guide
contaminants to move in one direction so that they eventually all end up on
the same side of the sieve. Such a device could be scaled to any appropriate
size to separate undesired contaminants and be placed inline in pipelines for
water purification. One potential arrangement, illustrated by Scientific
American, is shown in the following figure.
I don’t expect to see Brownian ratchets and sieves in any of the projects we
work on in the next five years, but if the technology continues to develop and
engineers at companies like Crown Solutions are able to find an effective
application, someday they may be just another tool to help us provide
comprehensive and effective water management solutions to our customers.
Reference: Atomic Spin-Offs for the 21st Century, Scientific American,
September 2004.
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