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I have used bleach to make rust(with salt), how can I seperate the rust from the salt? Answered

I was looking for a way to make rust (ironoxide) and found that bleach coul be used as an oxidizer; however, I would not know when it was finished breaking down. With some research I found that NaClO + H2O2 -> O2 + NaCl + H2O. I think I can use this to either: use the NaClO and make the ironoxide, then add the H202 to break do the residual NaClO (extra H2O2 can be evaporated with the H2O), or used the reaction to speed up the ironoxide making with a bit of extra H2O2 to insure all the NaClO is used and the evaporate off the rest. (which would be better? would be my first question, but not the most pressing one) My question is how can I sepperate the Iron oxide from the NaCl (salt), since both are water soluble (sp)? A filter will seperate out larger pieces of ironoxide, but there will still be a fair amount that passes through the filter with the salt and I would like to minimize my loses as much as possible.



Best Answer 9 years ago

iron oxide will be precipitate - and will come out of solution. Salt can be dissolved in water. Simply filter the rust out with a coffee filter, then rinse with distilled water (or tap water if you dont care) - then dry it.

From what I have read Iron oxide will also dissolve in water.

Where did you red this? Iron oxide won't dissolve in normal water. If you use hydrochloric acid instead of water, than it will dissolve, but in normal water, it won't. You can wait and the rust will go to the bottom of the solution, or you can filter it. //Normally metal oxides never dissolve in water, there are some metal oxides what react with water (potassium oxide ect.) and after the reaction the product can be dissolved, but usually the metal oxides are not water soluble.

I redid my search and found the artical and I miss read it (just that little difference of soluble and insoluble)

To speed things up, use hot water.

Thanks for your answers, and corrections to my misreading =)

Here is the process I have come up with and will continue to refine:
1) break down steal/iron wool in a clean empty container
2) cover with bleach (NaClO)
3) wait for a fair amount of oxidation to occure
3b) optional wait longer for the NaClO to disolve the steal wool a bit more
4) add H2O2 to rapidly consume the remaining NaClO
5) watch cool bubblely reaction (no worries just O2)
6) Filter solution to seperate most of the NaCl and FeO
7) Rinse FeO (likely in the same filter)
7b) Rinse again in a new filter
8) Set FeO to the side to dry

Now the Brine that was filtered off is still likely to have finer particals of rust in it, so I was think of some sort of magnetic filteration/capture method to collect it. (still working on this part)

The extra rinse probably isnt totally necessary, but you can't be too careful. The filtrate will likely remain reddish coloured as you suspect - because of minute particles. Short of getting lab quality filter paper and a nifty filter setup - coffee filter should do just fine :D

The #b) steps were all ment to be optional, the extra rinsing would be for case in which the rush would be used in an application in which salt would/could be an issue, such as if used as paint pigment, I could see salt being an unwanted purity (the amount that is exceptal and what extent you are willing to extra filter and rinse is a personal choice)

I want to get the minute particals, just to say that it is possible and that I can =)
Right now my basic idea is a shallow slope plastic troth lined with magnets (I recently stripped a number of crashed hard drives). Let gravity slowly pull the mixture along the troth and the magnets pull in the iron oxide. Then rinse or repeat (to personal desire)

Salt water and air will rust iron. Bleach is not stable dry, or in sunlight, so simply leaving it out in the sun will convert it to salt.
Rust has a low solubility, so I'd advise like Frollard
And start with iron-wool, or washed-Brillo pads.