Table 2: Chemical reactions between sodium hypochlorite and various dyes at 18^oC.

Dye	Observations and Results
Gentian Violet	All colouration disappeared immediately on mixing the dye solution with NaOCl in a beaker. Clear and colourless water has been the result. The reaction was so rapid that there was no time to introduce a sample of the reaction solution into the spectrometer’s cuvette.
Bromophenol Blue	Decolourisation has been attained in 1 hour, and final absorbance has been recorded at 0.08. The peak of the reaction solution at λ = 591 nm did not shift during the course of the reaction. Considering absorbances, the reaction was established as 1st order with respect to the dye (NaOCl in large excess). This classifies the redox reaction as pseudo 1st order.
Eriochrome Black T	The orange colouration of the alkaline EBT solution (pH = 12) was found to be absorbed at λ = 605 nm, but the peak shifted to λ = 531 nm on mixing with NaOCl. Another abrupt shift to λ = 395 nm occurred between t = 30 to 35 minutes from the commencement of the reaction. After 1 hour, decolourisation was not complete. A transparent but light yellowish liquid persisted with an absorbance of 0.62.