Is it possible to have higher degradation of wastewater in visible light?
I was degrading methylene blue using a photocatalyst and it showed higher degradation in visible light than UV light after 30 minutes. After 90 minutes however, UV light showed higher degradation.
Maybe the first 30 minutes reaction is not photocatalytic reaction. it might be an absorption process of the methylene blue by the photocatalyst semiconductor. after reach an equilibrium state, then it undergoes photocatalyst reaction, which showed by high degradation in UV light.
Thank you for the answer.
But in t = 30 mins, both visible light and UV light are tested.
Does this mean that UV light somehow slows down the adsorption process?
Use a cut off filter, i.e. perform the dye degradation tests under only UV light, and then only under visible light. In this manner a better comparison can be deduced.
If your catalyst is visible light driven then it will show higher degradation in visible light as compared to that of uv light. So measure band gap of your catalyst and then try the experiment in only visible and only uv as advised above
My catalyst is CuO/TiO2 immobilized by cement. We dont have the equipment to measure the bandgap yet.
And after 90 minutes, the UV lights shows higher degradation.
As you are performing dye degradation experiments, I believe you are using a UV-Visible spectrometer. The same instrument can be used to measure the absorbance of CuO-TiO2 and from that data you can find out the bandgap of your catalyst. Just few simple equations. So try measuring it.
I second the Jaideep Malik, as your material is working best in visible light, it means that impurities you introduced in TiO2, have reduced the bandgap of your material, bandgap calculation is must to know this. If you have the UV vis Spectrophotometer then you can make a diluted solution of your material in appropriate solvent and take %R readings of your material. After that apply the kulbul munk equation (F(R).hv)1/2 to get the band gap.
Please read some articles related to this, I done these calculations a year ago, this is what I remember now....:) Hopefully it ll solve the problem