Thread: electrolysis for rusty razor

I'll do a brief overview of a couple of things and then dig out some chemistry texts I have buried away after college if the population wishes for a more in-depth explanation.

To directly answer the plating question, yes, this is the exact process used for electro-plating. The solution may vary depending on the metal used, but I know a number of folks who have used this process to zinc plate motorcycle bolts.

The first thing to note is that I am going to make a number of assumptions about simple things, my copper tubing is pure copper, the tap water I'm using is just H2O, etc. I know these to be incorrect, but for the sake of simplicity and sanity I'm making them anyway.

An interesting fact about copper oxidation, unlike ferric(ous) oxidation, creates a protective barrier from future oxidizing. Steel/iron will rust all the way through. Copper will only rust until the metal is superficially covered/oxidized, then it will cease. Last fun fact, the washing soda (NaCO3), actually does nothing except make the solution electrical. The sodium carbonate dissolves in water to form Na++ and CO3-. Basically, these charged anions and cations are used to transport the different chemicals between terminals.

Rust is iron oxide (Fe = iron),((OH)2 = oxide). The iron has a charge of +2, the oxide a charge of -1. They combine then at Fe(OH)2, for a neutral state. So the electrons released from the positive terminal reduce the rust into Fe++ and 2(OH)-. The 2(OH)- joins up with the positive copper, creating the copper oxide. The iron snags the two electrons the copper released and returns to a 0 charge state, often ending up as a particulate in the solution, usually too small to see.

The water also electrolyzes and creates oxygen at the anode and hydrogen at the cathode, at a ratio of 2 hydrogens per oxygen (H2O).

Now, in our case, and after looking at your blade, we ran out of rust per say. At least easily accessible rust. The reaction always takes the easiest path. We have the sodium and carbonate ions from the dissolution in water. The copper 2+ joins with the carbonate anion (- charge) as a transport mechanism. At the negative terminal it regains the two electrons it lost on the positive side, only now it's stuck to the steel. We hit a balance point in the reaction where either we are actually out of rust, in which case there was no more OH for the copper to join up with. or it is easier electrically and chemically to plate the copper onto the steel than it is to try to dissolve more rust.

After digging into this farther, it seems the absolutely best possible sacrificial anode for rust removal would be neutral iron. Or steel with an iron content as high as you can possible find.

That was rather long and, in retrospect dry, but to the best of my knowledge the chemical and electrical reactions are correct. I can balance the math on here if people really want me to, but it's not going to be a fun read.