Electrochemistry help, ripples in current effecting reaction?

[Xtensity]

I've been messing around with basic electrolysis for the past 3 days making Iron Oxide from nails... So far its instantly successful with a 6v lantern battery, and another combination with 2 9v batteries in series. Well both of those ran dead so my dad let me borrow his 6v/12v battery charger. I hooked the anodes and cathodes up just how I had them previously, and even tried different variations... and there's no Iron Oxide forming... though I know the current is going through because I can measure a current starting at 20 miliamps, which overtime builds to 400+ miliamps.

The Hydrogen gas, Oxygen Gas, and even the Carbon Dioxide(from the baking soda electrolyte), form. There's constant bubbles around the electrodes but there's absolutely no rust forming.

My dad suggested that there could possibly be a ripple in the current which prevents the Iron Oxide from forming... A ripple that the 6v battery or the 2 9v's didn't have.Is there any reason why the Iron Oxide wouldn't be forming anymore but the other chemical reactions are continuing fine? Also somehow the conductivity of the water is increasing... which I think this is from the Baking Soda being electrolyzed into C02 Gas and other metals which get left in the water, though I'm not sure if this would affect the conductivity.

Could "ripples" in the DC current be effecting the reaction? If so how? With the 2 battery combinations the Rust/Iron Oxide started forming instantly, but even with this other set up using the battery charger going for an hour+, no rust forms, yet bubbles still occur at both electrodes. I even tried using several different types of nails as electrodes. Even the original nails that rusted fine do nothing with the battery charger set up.

Any ideas?

edit: I've also tried using nickel electrodes which DO react producing a greenish blue nickel oxide...this is with the battery charger set up... yet the iron oxide reaction does not work with this set up.

 

[jbsteele]

There could be several factors that are preventing the iron oxide from forming. First, the DC current from the battery charger may have too much of a "ripple" in it, which can prevent the iron oxide from forming. Additionally, the electrolyte may not have enough acidity to facilitate the oxidation of the iron, or it could be that the current is too high and is causing the water molecules to break down into hydrogen and oxygen before the iron can oxidize. Finally, the iron electrodes may not be pure enough to allow for the reaction to take place. If the iron is contaminated with other elements, such as carbon, the iron may not be able to oxidize properly.