During the study of photocatalytic properties of Zno/Cuo i kept the samples of methylene blue with certain amount of photocatalyst in sunlight for degradation.
After some time the colour of methylene blue become disappred as it seems degradation of dye was done.But when i removed the samples from sun light the blue colour has come again.
Why this was happening.?
Hafiz Muhammad Arsalan
The disappearance of colour does not indicate degradation of dye. Sometimes the dye gets degraded into intermediates/by-products that result in enhancement of absorption at lambda max.
Coming back to your question, it may be due to the desorption of dye molecules. We need a detailed procedure that you have followed, for better understanding of the problem you are facing.
Is the initial bule(?) color (spectrum) the same as the spectrum of the solution exposed to sunlight?
This could be caused by the desorption of dye molecules from the catalyst. And comparing the intensities of the dye before sunlight exposure and after that, is the colour thickness the same????There are lot of things to check in order to help you solve this.
Yurii V Geletii
No, there is a little bit difference between the two spectrum. But at that time when i removed the sample from sun light the blue color was totally disappeared.
i am shocked to see the blue color again. Potlako J. Mafa
The conversion of methylene blue (MB, blue) to leucomethylene blue (LB, colourles) is a reversible redox reaction. Under light MB is reduced, then in the dark LB is oxidized to MB probably by air.
"a little bit difference between the two spectrum" is a result of partial degradation of LB/MB
Agree with Yurii V Geletii
You may contact me at +923365816086. I have also working experience with MB.
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