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The Professor
The Professor, Taught at USC Years Ago
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Can a dissolved material (such as salt or powdered drink ...

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Can a dissolved material (such as salt or powdered drink mix) be completely filtered from water using some type of physical or electrical means which would leave the material behind and able to be dissolved again?
My credentials: perfect scores in high school and college chemistry. (In 1964 and 1965!)

Most salt-like dissolved materials cannot be "filtered". They are dissolved to the atomic level. Some organic molecules CAN be filtered.

Unless you consider reverse osmosis as a sort of "filtering", but most people don't. Reverse osmosis leaves a purer solution on one side of a semipermeable membrane and a more concentrated solution on the other, but both are still solutions.

http://en.wikipedia.org/wiki/Reverse_osmosis
http://science.howstuffworks.com/reverse-osmosis.htm

The process requires the input of energy.

Dissolved materials can be recovered from solutions by electrolysis. Once reclaimed this way, the salt-like recovered material can be dissolved again. Again, energy input is required.

Dissolved materials can be recovered by evaporating the solvent. The recovered materials can be dissolved again. Again, energy input is required.

Many organic molecules act "different" than inorganic molecules, but assuming your question is basic chemistry and not organic chemistry, it's a safe answer to say that "inorganic dissolved compounds generally cannot be filtered"".
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Customer: replied 8 years ago.
Sorry, I don't know etiquette for these things. If so, can I get another question? I'm kind of working on a low budget here, but your answer was definitely helpful. If I can get another question, how fast would regular osmosis work? Say, for instance, you have a container of salt water that is completely saturated, and on one end water is being forced through so the salt is salt is left behind (as with a semipermeable membrane) and on the other end there is another semipermeable membrane separating the salt water from completely pure water. Would the salt left behind pull the pure water through at the same rate it is being removed on the other end? If you cannot answer, then let me know and I will just hit the accept button. Thanks for your time.
Normal osmosis (and reverse osmosis as well) depends on several factors:

*The type of molecules on the concentrated side
*The concentration of molecules on the concentrated side
*The pressure differential, if any, across the membrane
*The type of membrane
*The temperature of the solution(s)

And so one cannot really answer what would happen and how long it would take unless these factors are specified.

And, I should hasten to add, this kind of analysis is a specialty in which I am not skilled, other than being able to relate the basics of the physical processes.

Hope these thoughts help.
Customer: replied 8 years ago.
sorry to keep bugging you...any chance you know anywhere i can go to help me figure all that out? i don't even know the options here, so...yeah. maybe something like an online textbook would help, if they make such things? thank you very much, though, even if you don't know where i should turn next
There are commercial firms that market reverse osmosis systems. They hire and probably train the chemists and physicists who specialize in this kind of work.

There may well be college classes that address this sort of thing as well. But in my Civil Engineering career I've not run across anyone who HAS specialized in this.

Sorry to have run out of answers!
Customer: replied 8 years ago.
no problem...what you were able to tell me was more than i knew, so thats at least something. thanks a ton for your time...i guess reply back and i'll hit accept
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