Selective/cumulative electrolysis ?

[Externet]

Hi.

By applying 0.1 Volt to electrodes in a solution of multiple compounds, as a murky river; would only one or a few elements be collected ?

If the voltage is increased to 0.2 V, would additional others join and get deposited ?

 

Stepping up the voltage, would more and more elements attach to the electrodes ? Is that the way it works ?

 

The metals or compounds being in minute nanoparticle concentrations, diluted or in suspension as in a river. Making the river to flow trough an electrolytic pipe internals, would such metals stick to electrodes placed inside the pipe ?

 

Is that the way the electrochemical series would work in electrolysis, cumulatively selecting different metals depending of the voltage ?

 

Am sorry about the poor terminology or attempt to express the question. In other words, would different voltages deposit different elements onto the electrodes ?

[elementcollector1]

I think the electropositivity / electronegativity of the ions in question would come into play. The least electropositive element would be electrolyzed at the least voltage / current. I think...

[Enthalpy]

I expect - but wait for other opinions - that 0.1V is too low for any effect. There are thresholds, higher that 0.1V, just because an electrode's surface isn't a clean metal, and differs from water as well.

 

You may use a low voltage when both electrodes are the same metal dissolved in the electrolyte, but even then, 0.1V is little.

 

If the voltage exceeds the minimum necessary for electrolysis to happen, I expect a small current density to first deposit fully the easiest metal, limiting the voltage to what this metal needs, and then the voltage to increase to deposit the second easiest metal - which may never happen in a river that replenishes the easiest metal. When all metals easier to separate than hydrogen are gone, you get hydrogen. Which isn't a strict limit experimentally.

 

The same should happen at the other electrode with the anions, complicating the voltage behaviour.

 

With a decent current density, the process is less selective and you get a cation and anion soup.

[Externet]

I just wanted a guess on what deposits to expect attached to the electrodes by electrolysis of a murky river carrying all sorts of minerals, using perhaps stainless steel anode and cathode plates; stepping trough different very regulated fixed voltages.

 

And if

-the electrochemical series list

-or the galvanic series list, as in ---> http://en.wikipedia.org/wiki/Galvanic_series

-or the standard electrode potential list as in ---> http://en.wikipedia.org/wiki/Standard_electrode_potential_%28data_page%29

 

applies in some form for the guess.

 

Or if am way off from expressing properly what am asking.

[John Cuthber]

"By applying 0.1 Volt to electrodes in a solution of multiple compounds, as a murky river; would only one or a few elements be collected ?

If the voltage is increased to 0.2 V, would additional others join and get deposited ?"

 

The simple answer is yes.

http://en.wikipedia.org/wiki/Voltammetry

but it's quite complicated.