RogueRose
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Making a bucket of rust - add salts and or electrolysis?
So I've collected a lot of steel and iron over the last years that I was going to take in for recycling but I thought I would make use of it before it
take it in by making some iron oxide since I have some uses for it.
The metal ranges from stamped sheet steel like the stuff used to make computer and printer cases (some seems like it may have a zinc coating or
something but it seems extremely thin, if it is in fact zinc at all). The rest is a mix of things like angle iron/steel, square tube steel, lots of
55 gal drum lids, appliance housing, machinery body steel, motor casing steel, brake drums, brake rotors & lots of odd cast iron pieces.
As far as using a salt to speed things up I have NaCl, KCl, MgCl2, CaCl2, ammonium sulfate, Na2CO3 & HCl. I have a DC power supplies of many
voltages from 3v to 20v and are capable of high amperages
3v - 200A
5v - 150A
7.6v - 120A
9v - 120A
10.8v - 100A
12v - 100A
16v - 80A
20v - 65A
For a container I have everything from a 5 gal bucket, 18 gal rubbermade tubs, 20 gal steel drum, 55 gal steel & plastic drum & 65 gallon
trash can, so I can put a lot of the steel in one of these but I'm not sure how this would work.
When I tried making iron acetate I put about 5lbs of nails in a 2L bottle with vinegar. It took FOREVER to make acetate/rust about 5-6 months. The
nails were submerged but the cap was off the bottle so air got into the bottle. When I replaced the vinegar I only filled 1/4 full so nails are only
70% submerged and it is working about 50x faster and I think it is because some of the steel is exposed to the air but IDK.
When I had some MgCl2 on some tools (by accident) it seemed to oxidize the steel extremely quickly and deeply so maybe that might be a good corrosive
salt to add to the water.
IDK if anyone has any experience with this and if you do I'd appreciate any suggestions on a good, easy method to do this, basically set and forget
until rust can be scraped off easily with putty knife or wire brush.
[Edited on 4-2-2018 by RogueRose]
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LearnedAmateur
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I used to make some electrolytic rust when I was playing around with thermite, could make a few grams at a time over a couple of hours (which is
pretty decent for the scale I was working with) using a 12V adapter that had the connections pulled off. Not sure on the current, 5A maybe, but I used
to just submerge the steel electrodes in saline solution and every hour or so, switch around the connections to corrode both electrodes - the rust
just falls to the bottom so it’s not like it’s getting reduced back into iron. I liked to keep the distance as close as possible for obvious
reasons, 1-2cm for small chunks of steel and steel wool, so if you want the fastest reaction and are using planar pieces, stick them face to face no
more than 10cm apart but you have to leave some space at the bottom of the container for rust to collect.
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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metalresearcher
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Fe2O3 can easily be bought online for a decent price on the internet.
Making it yourself works, but is a long lasting process as TO already describes even with his 100+ Amp electrolysis.
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Diachrynic
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Elektrolysis with NaCl works, but is not fast by any means. From my experience a 100 g/l solution of NaCl yielded a corrosion of 11 g on the anode
with 5 V / 2 A for 5 h, so 10 Ah for 10 g of lost iron is an estimation. No real weight gain on the kathode.
Iron alloys like stainless steel are quite stubborn in such a cell. They corrode, but will soon stop and you need to replace the solution even for
amounts like 10 g of stainless steel dissolved.
we apologize for the inconvenience
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AJKOER
Radically Dubious
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First comment, electrolysis is always slow by nature (Faraday's Law). Better is spontaneous galvanic reactions, especially involving aqueous iron
which can be activated in a microwave oven! Avoid using dry iron in a microwave due to the formation of dangerous high temperature sparks, arc,..,
best for another day.
An experiment previously reported:
Quote: Originally posted by AJKOER  | I tested my suggested Ferrous carbonate path with some success (at least enough to produce a visble color change).
In 5 hours, after heating 3 times for 30 seconds in a microwave, and periodic shaking, a mix of water, Iron filings, NaHCO3, to which is added a
small amount of vinegar (the latter two acting as a CO2 source with the Sodium bicarbonate in excess) with a touch of sea salt. I employed a sealed
and deflated plastic 3.3 liter bottle to address the CO2 gas expansion issue on heating. Note, acidic pH, increase in the partial pressure of CO2,
warming, agitation of solution and the presence of chloride and acetic acid are all reported as accelerating the corrosion of steel.
Per my cited reference by Anderko above with respect to a surface reaction forming ferrous carbonate:
Fe + HCO3- ⇒ ≡FeCO3 + H+ + 2e-
Other anodic half reactions:
Fe + OH- ⇒ FeOH + e-
FeOH ⇒ FeOH+ + e-
FeOH+ ⇒ Fe++ + OH-
Net: Fe ⇒ Fe++ + 2e-
Cathodic reaction (my expanded rendition featuring the hydrogen atom radical):
H+ + e- ⇒ .H
.H + .H ⇒ H2
As: HCO3- = H+ + CO3(2-) , we have similarly:
HCO3- + e- ⇒ 1/2 H2 + CO3(2-)
In my opinion, it may be further possible that:
HCO3- + .H ⇒ 1/2 H2 + .CO3-
with the possible transient formation of the carbonate radical anion. Its self reaction is said to proceed as follows:
.CO3- + .CO3- ⇒ CO2 + CO4(2-) (p. 11 at https://www.google.com/url?sa=t&source=web&rct=j&... )
Also, a possible reaction between the hydrogen atom radical (and/or e-) and the acetate anion or undissociated HAc, may account for the reported
acceleration of steel corrosion in the presence of acetic acid (thesis idea?, see https://www.google.com/url?sa=t&source=web&rct=j&... ).
Visible result was a light green solution. See picture in attached document.
[Edited on 12-5-2017 by AJKOER]
[Edited on 12-5-2017 by AJKOER] |
Link: http://www.sciencemadness.org/talk/viewthread.php?tid=73921
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Another thread with Fe2O3 and pictures: see http://www.sciencemadness.org/talk/viewthread.php?tid=153&am... .
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Want faster Fe2O3, see "Magnetizer and Chemical Reactions - Experiment" at http://www.sciencemadness.org/talk/viewthread.php?tid=77204#... .
[Edited on 2-4-2018 by AJKOER]
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