Firstly some questions: What is Your photocatalyst? UV or Vis? Concentration range of MO or MB?

Dear BOZENA CZECH@

ZnS/Graphene composite i am using as a photo catalyst

They show Vis activity so Xe lamp will be ok. Depending on the amount of GO (up to 10%) some of them shows high UV activity. Look at DOI:10.1021/nn304154s

You should use VIS or UV-A, be sure that you don't use UV-C because it can decompose your MB w/o catalyst.

Best regard,

Think about LED (Light Emitting Diod), much cheaper than Xe.

Uv LIGHT IS THE BEST ONE FOR PHOTOCATALYSIS. AT 450NM

Thank you for all valuable suggestions.

is tungsten lamp Ok for photo degradation of MB?

UV light sources is good for photo catalytic degradation of MB, MO pollutants.