A BubbleGeek's Sentiments concerning
sediments.
Cloudy gunk and it wasn't there yesterday... Is my $20 a
gallon solution going bad? But it still seems to work. Add
more water? Detergent? Citric Acid? Something else to raise
the pH? What to bring it back? How to avoid it?
These are the kinds of musings that keep me awake at night.
Looking at that layer of white sediment swirling
opalescently it is easy to think it is a biological
contamination. Like algae in a pool or what ever that stuff
is that blooms in my half filled cup of tea with cream when
I leave it in my parked car for a week.
Because I (used to) know little to nothing about chemistry
it has taken a long time to start piecing the clues
together. This is where I am right now.
Chemical reactions can make it seem like something has come
from nothing. I don't beat myself up about it because I can
not see down to the molecular or atomic levels. Thank
goodness. If I could, I might be tempted to watch the
"Cloud-Point Phenomena in Wormlike Micellar Systems" (the
catchy title of an American Chemical Society article from
2001).
"The Cloud point of a fluid is the temperature at which
dissolved solids are no longer completely soluble,
precipitating as a second phase giving the fluid a cloudy
appearance."
Q: Why should you care about cloud points? A: Because you
want to avoid them.
Q: Why aren't we exploring cloud points with serious
intent? A: Because it means skimming (to find the good
stuff) theses such as, "Physical Properties of Aqueous
Solutions of a Thermo-Responsive Neutral Copolymer and an
Anionic Surfactant: Turbidity and Small-Angle Neutron
Scattering Studies.
Anyhow. Our lubes and surfactants can both be the cloudy
culprits.
Some of the precipitate problems stem from our use of
polymers with long molecular chains. Lubes. Cellulose, some
glycols & the stuff in J-Lube for example. Heavy, long
chained molecules we use to adjust the solution
performance, they contribute to self healing.
Given the right conditions they can twine-up, gang up, to
form those clouds we see. They might wrap around a tiny
chunk of solution contaminant such as dirt or the minerals
in tap water. Sort of the way a raindrop is formed when
enough water molecules glom onto a speck of something in
the air.
This might be a reason to switch to distilled water, which
is certainly cheap and easy enough to find in the US. It is
void of nearly all of the minerals which might be the seeds
of my milky problems. But the lower pH of distilled water
might cause other problems like throwing off the surfactant
action. So I thought, how about rain water...? Can't get
purer or more natural than that. It must have a near
neutral pH (7). Rain water does however turn out to have a
pH of...
"... 5.6 in those areas of the world where there are no
direct industrial pollution. Otherwise, the value is
typically lower than that. Rainwater is naturally acidic
due to carbon dioxide in the atmosphere. When water and
carbon dioxide come together they form an acid known as
carbonic acid. So, natural rainwater has been and always
will be acidic. Other gases occurring from natural sources
like volcanoes will also add to the acidity of rainwater.
However, in industrial areas the acidity of rainwater will
increase down wind. Acid rain is considered any rainwater
that has a pH of less than 5.6."
Surfactant systems usually like it best when operating at a
slightly elevated pH (how base!). What is a bubbler to do?
Either the salts will get you or the low pH of the water
containing less unwanted stuff will.
Okay. This time I've kept my mix clean, unopened. And I was
careful in preparation to wash all the utensils first. This
time, after I notice the cloud, I wonder if "fall out"
could be temperature related. Like the tea, I left it in my
car.
Back to research. Email to my chemist friend. And those
scientific papers...
Surprise! I can easily find evidence to support the
temperature theory. Nonionic surfactants (regularly found
in liquid dish detergents) are prone to the dreaded
condition:
"...Nonionic surfactants become water soluble by the
hydration of ether oxygens of the polyoxyethylene group.
The longer chain of ethylene oxides containing ether
oxygens is, the more hydration, and consequently, the more
solubility. An increase in temperature causes the cleavage
of the hydrogen bond between the ether oxygen of the
ethylene oxide group and the hydrated hydrogen to the ether
oxygen."
A ha! Temps change and the ooze appears. But wait there's
more!
"...The depletion of water from nonionics results in the
decreases of the water solubility of nonionics. The water
depleted nonionic surfactant solution, therefore, becomes
turbid and seperates into two phases including a insoluble
hydrophobic precipitate. This sudden onsetting of turbidity
of a nonionic surfactant solution when the temperature is
raised is called the "cloud point". In general, nonionics
having a longer polyoxyethylene chain consequently have a
higher cloud point, meaning a greater capacity to hydrate."
Yep. That would make the yuck too. I left the pan open to
the air for too long between dips. Evaporation?
Maybe, if I add in a little more water...
Maybe, a bit more research?
How can I be *sure* it isn't a microbial problem????!
Such is the life of a bubblegeek.
Keith