A kinetic model that describes removal of chromium VI from rinsing waters of the metal finishing industry by electrochemical processes

A study was made to remove Chromium VI (Cr super(6+)), present in large quantities in the rinsing waters from the plating industry, using electrochemical treatment. Large amount of Cr super(6+) are found. It was found that the reaction rate followed a variable kinetic order at concentrations up to 1...

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Bibliographic Details
Published in:Water Science & Technology 2000-01, Vol.42 (5-6), p.55-61
Main Authors: MARTINEZ, S. A, RODRIGUEZ, M. G, BARRERA, C
Format: Article
Language:English
Subjects:
Anode effect
Anodes
Applied sciences
Cathodes
Chemical treatment
Chromium
Corrosion
Corrosion prevention
Electrochemistry
Electrodes
Environmental protection
Exact sciences and technology
Ferrous ions
Heavy metals
Industrial wastewaters
Iron
Metal finishing
Metal finishing industry
Mexico
Pollution
Removal
Rinsing
Salts
Sludge
Wastewaters
Water treatment and pollution
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Description
Summary:A study was made to remove Chromium VI (Cr super(6+)), present in large quantities in the rinsing waters from the plating industry, using electrochemical treatment. Large amount of Cr super(6+) are found. It was found that the reaction rate followed a variable kinetic order at concentrations up to 1700 mg Cr super(6+)/L. It was also noticed that Cr super(6+) reduction depended on the ferrous ions (Fe super(2+)) released at the anode, the cathode reactions and the acidic corrosion on electrodes. Iron salts produced electrode passivation and it caused a 50% increase in treatment time and power requirements. Eliminating the salt formation at the anode could reduce this effect. Using electrochemical processes it is possible to reuse treated waters in the rising stages of the plating industry owing to the fact that final Cr super(6+) concentration is less than 0.5 mg/L. Finally, a sludge characterization study revealed that residue generated in the process is not considered dangerous according to Mexican environmental protection standards.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2000.0495