The answer to your question depends on which kind of adsorbent surface you want to prepare or for what purpose you want those chemicals species to be adsorbed on Pb surfaces, if you can provide me with what you exactly want then i can answer that approximately which of the chemical species can be used for that purpose.
BET method is preferred choice for higher relative surface areas like porous materials, activated carbon ,quantum dots materials,graphene and nanosized metal oxides.I thinck the Lanqmuir model is compatible with metals which have low relative surface areas.
The adsorption on the particular metal as lead metal which is dependent on the type of species( chemical structure , charges of surface , electron density , etc...). You can simply use Cl- ions as good attractive with this metal in electrochemical methods to absorb it.