user manual

Appendices
January 2009 UDA2182 Universal Dual Analyzer Product Manual 211
negative. The chromium, an oxidizing ion, Cr
+6
, accepts electrons and makes the
electrode more positive. The net electrode potential is related to the ratio of
concentrations of reducing and oxidizing ions in the solution.
Potential cannot be used as monitor of effluent
This electrode potential is extremely sensitive in measuring the degree of chrome
treatment in the reaction tank. However, it cannot be related to a definite concentration of
chrome and, therefore, cannot be used as a final effluent monitor of chrome
concentration.
Importance of clean electrode
Reliable ORP measurements require a very clean metal electrode surface. Clean the
electrodes routinely with a soft cloth; dilute acids, and/or cleaning agents to promote fast
response. Control at low pH levels in the first stage of treatment has also been found to
help maintain clean ORP electrodes.