How to select the measurement for Redox electrode materials,gold? Silver? Or platinum?
How to select the electrode material is used for Redox
Gold? Silver? Or platinum?
Platinum is common electrode material, can't use only a few occasions.
In ozone (O3) or hydrogen (H2O2) environment platinum oxide as catalyst, so under the condition of low concentration, build up in a composite layer with O3 or H2O2 the potential.
In addition, the platinum in air oxidation, let alone in the strong oxidizer. The first case, the electrode indicates the Redox value too high, and in the second case, there is storage effect. In these cases, there are slow response performance.
As a principle, in too oxygen or ozone applications can use platinum electrode.
In the above applications can use the gold electrodes, gold electrode potential is more advantageous than platinum electrode is, gold or silver electrode used in waste water containing cyanide detoxification also have strengths. Cyanide effect of corrosion on the electrode surface is weak, it makes the electrode surface clean.
Gold cannot be used in high chlorine content in acid solution, and because gold can form complex with chlorine disable measurement.
Required for the structure and measuring cables, pH measurement principle is also applicable to Redox measurement. Is measuring the impedance of the amplifier must also require input with high Ω (1012). Redox values with absolute or relative "mV" value display.
Redox is a kind of combined parameter measurement, it can't be used for measurement of certain certain ions.
So to the Redox system, is also impossible to measure the concentration of the specific, because in the process of oxidation reduction, existing in the solution of all ions are involved. Oxidation-reduction electrodes in that cannot be measured medium for chemical cleaning, because the use of cleaning fluid has a high concentration of ions content, after the high concentration of ion content and potential impact, potential to restore to the original process of measured data Is very slow.
If the process must be cleaned, the only or with ultrasonic method in mechanical way.
On the outside of the measured medium can put electrodes in sulfite solution slightly dipped below, with sulfuric acid or hydrochloric acid.
A Redox failure mainly in the reference of measurement chain system, the manifestation is the zero drift. The criterion for zero is is, for example, use 225 mv Redox buffer. The slope of Redox electrode will not change.