COBALT(III) OXIDATION OF ORGANIC-COMPOUNDS AND ITS APPLICATION TO A DETERMINATION OF CHEMICAL OXYGEN-DEMAND AT ROOM-TEMPERATURE

Cobalt(III) oxidation of diverse organic compounds was studied in a ba tch system. An aqueous solution of an organic compound was mixed with a cobalt(III) solution (ca. 0.04 mol dm(-3)), prepared through the ele ctrolysis of a cobalt(II) solution in a strong acidic medium, with a v olume ratio of 1:2. The oxidation of the organic compound was evaluate d from the decrement in absorbance of the mixed solution at 610 nm, th e wavelength of absorption maximum of the cobalt(III) ions. The cobalt (III) ions were found to be strong enough to oxidatively decompose org anic compounds at room temperature; the oxidation was rapid and almost complete in 10 min. The chemical oxygen demand (COD) of sample soluti ons was calculated from the amount of cobalt(III) ions consumed for th e oxidation. The obtained COD value for each sample was comparable to that determined by an official method based on permanganate oxidation. It is concluded that not only is the cobalt(III) oxidation practical for the treatment of organic compounds but it has possibilities as a n ovel method of COD determination, because it can be done rapidly in a simple operation with no requirement for heating.