Electrochemical treatment of effluents containing Cr(VI). Influence of pH and current on the kinetic

Compounds of Cr(VI) are very toxic and their reduction to Cr(III) is necessary to allow their further precipitation or adsorption. Chemical methods for Cr(VI) reduction are usually used for this purpose. As an alternative, electrochemical methods using three-dimensional electrodes, such as reticulat...

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Bibliographic Details
Published in:Water research (Oxford) 2006-05, Vol.40 (8), p.1555-1560
Main Authors: Ruotolo, L.A.M., Santos-Júnior, D.S., Gubulin, J.C.
Format: Article
Language:English
Subjects:
Applied sciences
carbon
catalysts
chromium
Chromium - chemistry
Chromium(VI)
Current efficiency
effluents
Electrochemistry
electrodes
Exact sciences and technology
Hydrogen-Ion Concentration
Kinetics
optimization
Other industrial wastes. Sewage sludge
Pollution
Polyaniline
Reaction rates
reduction
Reticulated vitreous carbon
Wastes
wastewater treatment
Water treatment and pollution
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Summary:Compounds of Cr(VI) are very toxic and their reduction to Cr(III) is necessary to allow their further precipitation or adsorption. Chemical methods for Cr(VI) reduction are usually used for this purpose. As an alternative, electrochemical methods using three-dimensional electrodes, such as reticulated vitreous carbon (RVC) and polyaniline-modified RVC, have been used successfully. Since the pH affects reaction of Cr(VI) reduction, in this work its effect on the reaction rate was studied using electrodes of RVC and RVC/PANI. While a maximum in reaction rate was found for a pH 1.5 using the RVC, the RVC/PANI showed no differences in reaction rates in the range of pH between 0 and 1. Practically, no reaction was observed for any pH greater than 3. The effect of different current densities using optimized pH was also evaluated and the RVC/PANI electrode showed the best reaction rates, current efficiencies and energy consumption as a result of the polyaniline electrocatalytic effect.
ISSN:0043-1354
1879-2448
DOI:10.1016/j.watres.2006.02.005