I am currently working on a photocatalysis experiment using TiO2 (doped with Nd). I am observing excessive adsorption of the pollutant (methylene blue) on the TiO2 surface. The absorbance drops significantly from 2.8 to 1, indicating strong adsorption. However, it seems that no photocatalytic degradation is taking place after adsorption, as the absorbance does not decrease further under UV light.
Additionally, my experiments are conducted at a pH above 8. I used both NaOH and ammonia solutions to increase the pH, but I observed the same result. Interestingly, after some time under UV light, the absorbance of methylene blue actually starts to increase again.
how can I treat the cause of the problem?
I think majorly there could be two factors at play, Recombination dynamics and effect of pH. I am rationally assuming you are using the correct wavelength of light for TiO2 it is
Ravi Teja Addanki Tirumala first thank you very much for your answer. I would like to share some details about my experiments. I used the same amount of catalyst and the same methylene blue concentration with Nd-TiO₂. I initially tested the methylene blue at its natural pH (around 6), but the activity was quite low, with only 3.5% adsorption in the dark. I then tested at pH 7 the result was the same situation that occurred at pH 8. What are your thoughts on this?
Dear Reham Dabboura, Solution pH determines the surface charge photocatalyst. for example, Titania surface remains positively charged in an acidic medium and negatively charged in alkaline media. So you read this review article. I hope it will help you.
Title: A review on the factors affecting the photocatalytic degradation of hazardous materials
Authors:A Kumar, G Pandey
Journal:Material Science & Engineering International Journal
Volume 1 Issue 3 - 2017
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