Abstract
Chromate plating activities are almost associated with certain amounts of hazardous chromium wastes which might be considered as resource losses that can be detoxified and recovered to usable product. The recycling of chromate from aqueous electroplating sludge by oxidizing Cr (III) species to Cr (VI) form has been studied. Wet chemical oxidation was attempted with hydrogen peroxide to oxidize the Cr (III) contained in a freshly collected aqueous ferri-chromium hydroxide sludge in slightly alkaline media (pH=8-9) at room temperature (25±5). Complete oxidation of Cr (III) with hydrogen peroxide could not be achieved. A maximum Cr (VI) recovery of only 77% was obtained using 30.8 mm/l of Cr (III) as initial concentration initial. The oxidation reaction kinetic was found to be dependent on trivalent chromium concentration and oxidant concentration which is described by the following rate equation:
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