Science Buddies: "Ask an Expert"

I have to make a water filter that can remove vegetable oil and iron ions (Fe 3+) from water. I have done a lots of research on the internet but can't find an affordable way to get rid of the ions. Any help or ideas would be greatly appreciated!

Hi mg0702,

Ion exchange is a common process for removing iron ions from water. More details are available at the following link.

https://en.wikipedia.org/wiki/Ion-exchange_resin

If the iron concentration is high, it may be possible to precipitate iron hydroxide. This requires adding either ammonia or sodium hydroxide. The water may be filtered to remove the precipitated iron. Additional steps would be needed to remove any excess ammonia or sodium hydroxide.

I hope this helps. Please ask again if you have more questions.

A. Norman

Thank you so much for your answer.
If I understand well, ion exchange resin could be used to replace iron ions by some other ions in the water. Therefore, the water would still conduct electricity when being tested unless we manage to remove those new ions. I know that this can be done with reverse osmosis, but I'm not sure if it would be possible to build such a thing.

Is there any filter media that could remove the iron ions? I read that greensand is sometimes used, but I'm not quite sure how it works.

Also, would it be possible to precipitate the iron by adding some sort of anion in my filter? Or maybe soap?

Thanks

Hi mg0702,

You are correct that ions are replaced in an ion exchange process. It's possible to produce deionized water with an ion exchange resin. The following link has more information about various water purification processes.

https://en.wikipedia.org/wiki/Water_purification

Please post some details about your science fair project including your hypothesis and a short description of your experiment. This information will help if you have additional questions.

I hope this helps. Please ask again if you have more questions.

A. Norman