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Are there any simple methods to completely remove nitrate ions from few ml of impure water sample?

One method I am curious about is the following process:

  1. Add one or more reagents to water in test tube, which would crystallize nitrate ions into some solids
  2. Then filter out the solids from water such that the water is now nitrate free.

Is the above process possible? If so, what are some reagents that can be used?

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Precipitation won't work

Nitrate removal is a very tough problem in wastewater treatment. One of the reasons is that nitrate salts of nearly every common cation are highly water soluble. Unfortunately, I can't think of a way to precipitate nitrate from your water sample.

How commercial nitrate removal processes work

Nitrate is removed from wastewater through a microbiological process called denitrification. In this process, organic carbon substrates are used as food by special anaerobic bacteria. In the absence of oxygen, the bacteria use nitrate as an electron acceptor so they can oxidize their food and obtain energy via respiration. As an example organic food molecule, consider hexose sugar. Then the reaction could be written as:

$$\ce{5 C6H12O6 + 24NO3- -> 30CO2 + 24 OH- + 18H2O + 12N2} $$

It will be difficult to purify a few mL of water in this way unless you know exactly the BOD of the water and are an experienced microbiologist with access to cultures of the appropriate bacteria.

Another not very good option

Another possibility would be electrochemical removal of the nitrate. That is a topic which has been researched but which is not practices commercially to any significant extent. Here is one paper where you can read about the technique. I don't think it would be very easy for a home chemist either.

The tried and true

That leaves more tried and true methods. You've simply got to distill your water! Boil it and collect and condense the steam and you'll have substantially purified water to behold and enjoy!

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  • $\begingroup$ Thank for the info. Looks like nitrate detection and removal are quite complex tasks for someone like me, without the relevant technical expertise. I feel i should be looking for commercial solutions. If possible can you please suggest where i can get info about the available commercial solutions. Should i post a new question on this forum, with my exact requirements? Is there anyother better place on StackExchange for that question ? Thank you for your time and effort. $\endgroup$ – Jason Apr 4 '15 at 3:50

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