Depending on the size, shape of the particles/granules you may see the surface morphology by a light microscope. If the particles are in the micron/submicron or nanosized then please use a AFM or SEM method. To compare the morphologies of your materials use the untreated material as a reference. It is very difficult to say about the resolution exactly. Just prepare the sample and try to observe the sample under low energy (kV).

@Rahman Thank you so much.

Sir, can you please suggest proper reference for the study. Also, proper protocol for sample preparation. My samples are not in micron, it's larger (0.5cm).

Thanks

Please refer to this relatively related answered issue on ResearchGate:

https://www.researchgate.net/post/How_to_find_the_size_of_roughness_grooves_from_power_spectral_density (in particular references by Panda et al. and D.J. Whitehouse).

About resolution, follow https://www.researchgate.net/post/Roughness_in_funciton_of_scan_size

You can see my previous answers:

https://www.researchgate.net/post/How_to_prepare_a_colloidal_Ag_NPs_samples_for_XRD_SEM_AFM?_iepl%5BgeneralViewId%5D=VHJX6ZLZIOY1fELH3CFAH0o0pW0MRCnFVvrZ&_iepl%5Bcontexts%5D%5B0%5D=searchReact&_iepl%5BviewId%5D=bn1mI1ocxi7S8PL1lkD12ueiX5UukjXfBCNy&_iepl%5BsearchType%5D=question&_iepl%5Bdata%5D%5BcountMoreThan20%5D=1&_iepl%5Bdata%5D%5BinteractedWithPosition11%5D=1&_iepl%5Bposition%5D=11&_iepl%5BrgKey%5D=PT%3A5b41a70d10569f10a549311c&_iepl%5BinteractionType%5D=answerQuestion