Dear Chandrika,

I Think the repulsion force between negative OH and anionic dye can affect the coagulation process. In your case it can consider in coagulation treatment not degradation. Many techniques were used for dye removal such as degradation ( biological, AOPs, Fenton reagents ,nano zero metals, etc...), and adsorption using natural and chemically prepared sorbent materials.

Yours'

Ahmed

Chandrika Pal

You added alkali to increase the pH, and under these conditions, crystal violet precipitates.

https://ru.wikipedia.org/wiki/Crystalline_violet

Interesting. But degradation and precipitation are two different things. In the first your compound will degrade possibly to simpler compounds or may the end product as CO2. The precipitation on other hand will precipitate CV to its hydroxide form. You will still have to deal with the precipitated form of CV which will be in a solid form.

Hope it helps.

Akshay

Chandrika Pal

Maybe at extreme basic pH, ionic product of solution is becoming higher than solubility product which can possibly form the precipitate. I hope this answer is suitable for your query. Best luck with your research !!

Have you considered the possibility of formation of the carbinol base form of CV from prolonged exposure to alkalinity? Such a form is uncharged and water insoluble unlike cationic, water soluble CV. The former specieis absorbs only in the UV and thus is not intensely coloured.