RogueRose
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3 step ultra pure water
I've seen some ultra pure water listed on various chem sites and it is outragerously expensive for being only H2O. Some say they are double distilled
and others don't mention the steps of purification or production (possibly burning H & O)?
I was wondering what other thought about the following method of production.
First, a dehumidifier is used to extract H2O from the air. The dehumidifier is sterilized as much as possible and a hepa filter used to filter any
incoming air with a positive air pressure passing over the condensing coils which should keep most new bacteria from landing on the coils and falling
into the water. From what I have read this process produces a deionized water that is pretty close to distilled water as far as removing salts and
trace minerals.
Second - run the collected water through a reverse osmosis filter (don't know if there are different levels or qualities of filters..?).
Third - Full distillation. A normal distillation setup with an airtight collection container at the end of the condenser. I'm curious if there is
any benefit to running a distillation unit under pressure, like using a pressure cooker instead of a standard pressure still or the opposite, under
vacuum which I believe would require less energy/heat. Higher pressure seems like it would be easier to do as pulling a vacuum enough to make a
difference might end up costing a decent amount.
After the distillation step it seems the most difficult part will be moving the (what should be sterile) water to a sterile container.
The reason I have opted for the above 3 step process is due to the fact that the first step has to be done either way in my current situation so I
have production that would otherwise be wasted. RO seems to be a fairly low energy endeavor when dealing with the water from the dehumidifier.
Distillation seems to be the largest energy & time expense.
This leads me to my next question about methods of sterilizing containers whether they are glass or plastic. I guess that should be another thread
though.
Any thoughts on the best process, alternative processes or modified processes?
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vmelkon
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Wouldn't it be easier to double or triple distill water under minor vacuum?
For sterilizing a container, perhaps wash with pihanna solution. That should burn away microbes and convert to CO2 + H2O.
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byko3y
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What is the application of water? A drinking water with normal salt content, or maybe a regular distilled water, or sterile water for biology, or
CO2-oxygen free, or water without isotopes? Sigma aldrich sells more than twenty different kinds of waters.
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aga
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For Chemistry, just distill any water twice.
Calibrate the thermometer.
On the first run, throw away anything than comes over at less than 100 C.
If there is any fraction < 100 C, wait a few minutes after it stabilises at 100 C to wash the apparatus out before swaping receiving flask.
If the thermometer reads anything above 100 C, immediately stop the distillation and immediately swap the receiving flask.
Clean all the equipment (using the once-distilled water) and then do it all again.
This water will probably be cleaner than whatever other reagents you use.
If it's guaranteed bacterial/viral cleanliness you want, reflux at higher pressures for a few hours as well.
Reverse osmosis equipment is not so expensive.
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Texium
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It's suitable to simply buy distilled water from the grocery store. I buy it by the 2.5 gallon jug with pour spout, and it's quite inexpensive. For
all home lab purposes, this water is more than clean enough.
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aga
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Same here.
Supermarkets here sell Distilled Water and pretty much clean 20% HCl in a 5L bottle alongside Sodium Hydroxide as well. All cheap.
Have to go to the Garden Centre for all the rest (and i really do mean All !)
However, if you are unfortunate to Not live Here, just distill your water twice and it will be cleaner than any of your other reagents.
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feacetech
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Distill then pass through your choice of filters.
In the lab I take tap water pass it through a course filter into a still upon exiting the still I pass it through a DI filter I can easily achieve
water with <2 us/cm conductivity this way and when the conductivity is greater than 2 i changed the DI column. You can probably obtain much purer
water with a different choice of after still filters
This water can be used to make up media for micro testing however it still needs autoclaving but this is probably more to do with the contamination
during the making (autoclave after) then pouring again autoclave after.
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macckone
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Depends on the water use. For certain kinds of analytical chemistry and for manufacturing semiconductors any ionic compounds are deleterious. Ion
capture resins are required. But those can introduce organics. Distilling through glass multiple times is preferred for other uses. For most of us
the distilled water we can buy is fine.
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