Redox potential

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The abbreviation for Reduction-Oxidation Potential (ORP). It is a measure of the tendency for oxidation or reduction to occur. A high positive redox potential indicates an oxidising environment, a low negative value indicates a reducing environment.

How to measure redox potential?

Any oxidation-reduction (redox) reaction can be divided into two half reactions: one in which a chemical species undergoes oxidation and one in which another chemical species undergoes reduction. The redox potential is the reduction/oxidation potential of a compound measured under standard conditions relative to a standard hydrogen half-cell. A system that accepts electrons from a normal hydrogen electrode is a half cell that is defined as having a positive redox potential; whereas a system that donates electrons to this hydrogen electrode is defined as having a negative redox potential.

Redox in bioleaching

One investigation [1] showed that chalcopyrite leaching is dependant on redox potential, and occurs between 650-800mV (SHE) at 35 degrees and 70 degrees Celsius. Best leaching was achieved between 750-800mV (SHE) at the higher temperature.


  1. Investigation into the ferric leaching of chalcopyrite at controlled redox potentials E.G. Jeevaratnam, T.A. Furamera and G.S. Hansford (University of Cape Town, South Africa)
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