Removal of chromium hexavalent from rinsing chromating waters electrochemical reduction in a laboratory pilot plant

In this work, experiments in a 16 L operating volume laboratory pilot plant with ring iron rotary electrodes were performed, obtaining an overall kinetic equation rate of hexavalent chromium reduction concentration and current density-dependent. Other scale-up criteria such as Reynolds' number...

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Bibliographic Details
Published in:Water Science & Technology 2004, Vol.49 (1), p.115-122
Main Authors: Martínez, S A, Rodríguez, M G, Aguilar, R, Soto, G
Format: Article
Language:English
Subjects:
Carcinogens, Environmental - chemistry
Carcinogens, Environmental - isolation & purification
Chemical reduction
Chemical treatment
Chromating
Chromium
Chromium - chemistry
Chromium - isolation & purification
Current density
Electrochemistry
Electrodes
Hexavalent chromium
Iron
Kinetic equations
Kinetics
Laboratories
Models, Theoretical
Oxidation-Reduction
Pilot plants
Rinsing
Wastewater treatment
Water Pollutants - isolation & purification
Water Purification - methods
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Summary:In this work, experiments in a 16 L operating volume laboratory pilot plant with ring iron rotary electrodes were performed, obtaining an overall kinetic equation rate of hexavalent chromium reduction concentration and current density-dependent. Other scale-up criteria such as Reynolds' number were also evaluated to ensure a completely stirred reactor at low energy expenditure. A dimensionless N(E) is a relationship between liquid properties and the electric charge supplied to the system. The number, which depends on the rotation iron ring electrode speed number and the current density, is proposed to be used as scale-up criterion. It was found that at N(Re) = 42,179 (130 rpm rotation electrodes rate) and at N(E) = 9.8 x 10(5) (current density of 113 A/m2), complete mixing was reached at minimum energy spent and the process becomes more efficient. In addition, it was found that the higher the current density, the less treatment time and less energy spent on agitation. After the electrochemical treatment the Cr(VI) concentration in the rinsing wastewater was less than 0.5 mg/L.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2004.0034