In general, before starting the adsorption experiments, the adsorbent is thermally conditioned at an appropriate temperature (based on the TGA data) under a nitrogen flow to get rid of any pre-adsorbed impurities and make the sorbent ready for operation. Is a similar procedure also recommend for TiO2 particles (powdered)? if so, can you recommend an optimum temperature (and duration) to do so without disturbing the TiO2 framework?
It depends on your TiO2 allotrope and morphology. Anatase can be relatively sensitive to temperature. Some morphology-controlled high surface area samples I've worked with showed surface alteration starting at 400°C, and complete morphology collapse at 500°C : Article Morphology control of anatase TiO2 for well-defined surface chemistry
At higher temperatures, it will even convert to the rutile phase.
Rutile, being the thermodynamic phase, is more heat tolerant. Its Tammann temperature has been determined to be around 600°C, anything below that should be safe.
Article ESR determination of TiO2 and SnO2 Tammann temperatures
Record a TG curve and find the temperature above which there is no mass loss due to surface adsorbed removal. Under such conditions you will have a OH-rich surface, ideal for most of photocatalysis processes. If you want to remove or to define the surface concentration of OH groups, you can increase the temperature (simply calculating the mass loss due to OH removal, transform mass loss of water to number of surface OH groups, and then divide this value by the specific surface area. Regarding the time, 3-4 h is usually enough.
Dear Prof. Rives, thank you very much for the kind info!! It's really helpful! Thanks.
I agree with V. Rives that you must do the TGA analysis to determine the melting point of your NPs. Infact this applies for all materials invariably in case you perform some heat sensitive applications.