jimmyboy - 16-5-2004 at 00:50
This is more of a electrical physics type problem but electrolysis is central to most chemistry so I'm gonna see if anyone can help. Right now i
have a few old fan motors/alternators sitting around the garage - i was thinking about the proper ways to connect these in series or parallel to drive
an electrolysis circuit - I want to connect them in parallel to get the most ampage possible - 12v should work fine - i was wondering if DC was
essential to electrolysis in the first place - if i used two alternators generating AC out of phase all connected to their own lead cathodes/anodes
would i not get the same effect? (each alternator would be connected to an anode/cathode making four separate electrodes in the same tub - filled with
water and whatever electrolyte if feel like)
or is rectification essential for electrolysis. If anyone has tried this or knows what would happen please tell.
Thanks
madscientist - 16-5-2004 at 01:57
Alternating current will work for electrolysis, but the cations and anions will be drawn to the same electrodes, unlike with direct current
electrolysis.
vulture - 16-5-2004 at 07:56
Hmm, I thought AC electrolysis would yield squat, because your electrodereactions are immediatly reversed back and forth.
jimmyboy - 16-5-2004 at 10:00
Actually the electrolysis will probably reverse right at the electrodes but not the same way - NaCl would break down into both NaOH and Chlorine gas
- and since they would be directly in contact with each other they would react - but they wouldnt reform salt by itself - hypochlorite byproducts -
and eventually chlorate. If DC isnt needed for electrolysis then theoretically (im guessing) you could hook your electrolytic circuit directly to
your AC outlet - or maybe that would blow a fuse - probably wouldnt be a problem as long as you made sure of your electrolyte concentration (needs to
be a load on the circuit to prevent short) - I'm not 100% sure of this though.
Organikum - 16-5-2004 at 10:46
If aqueous HCl is present AC will detoriate every electrode.
It is a good way to produce PdCl2 and hexachloroplatinic acid from the metals though.
jimmyboy - 16-5-2004 at 10:59
So AC would just disintegrate the electrodes? or maybe carbon would work?
axehandle - 16-5-2004 at 11:26
Having the hydrogen overpotential switching from negative to positive every 1/100th second would probably kill most electrodes -- but then that would
depend on the electrolyte.
hodges - 16-5-2004 at 12:34
Just buy either a diode (okay) or "full wave rectifier" (better) from Radio Shack and it will convert the current from your alternator to DC
(well, pulsating DC but the polarity will be constant so should work for electrolysis). Should only cost a few dollars at most. Just be sure the
diode or rectifier you buy is rated for the voltage and current you will be using.
Organikum - 16-5-2004 at 14:52
Yes there is no electrode material known to me which will withstand aqueous HCl under AC. High amperage not to talk about. Graphite gets eaten already
with DC in HCl/H2O.
But you should have a nearer look at your motors as it is quite probable that there is one or more a DC motor with integrated rectifier. Those with
brushes should be if I remember right. Thus a motor may be used as generator driven by another AC or DC motor (or several) and you have got your
wanted DC output. Power can be regulated by regulating the driving motor. This setup was commonly used in laboratories for the production of variable
DC before laboratory PSUs got cheap and relieable. A flywheel smoothes the power output - recommended. The connections between the motors must be made
elastic - two plates with rubber in between or the bearings will go down in no time.
The most heavy one of those motor-generator couples I have ever encountered was hidden in the basement of an old cinema where a AC e-motor drove an
very large DC generator with a heavy flywheel also to generate times ago the high amperage/low current DC which was needed to power the arc between
the carbon rods used to light the projectors. The projector housings where still the old ones where the fixations for the rods could be seen and parts
of the adjusting mechanic was still present too.
eh, back on topic:
The motor-motor coupling is a good and functional idea which got forgotten also it had and has advantages in generation of AC as in DC for
experiments.
- The circuits are decoupled, so you cannot blow your fuse or kill electronics by accident.
- It is possible to generate AC of varying voltage and frequency if the setup is made right.
- It is easy to either control amperage or voltage output.
- There is a impressing high power output possible with power peaks far exceeding what comes from the line or the original layout of the
motor/generator, the first if a big flywheel is used and the second one comes from the fact that all e-motors can be massivly overloaded for a short
time without damage - all automotive starters work by this principle.