So, in what form are your heavy metal ions brought in? Are you using a solution or a molten salt? In the first case, you can just do a classical microscopic sessile drop or sessile bubble (preferred) analysis. In the second case, those methods are in principle applicable, but of course you will have to build a setup that provides a well-defined temperature. Was that the point of your question?

C active or ultrafiltration and reverse Osmosis

I think using SEM will be useful to check the surface of your matrials.thesilica has distinguish surface and you increase the scale to check the contact angle

@ Jürgen Weippert Thanks for your comment. I am going to use heavy metals solution for adsorption process.